fbpx
Wikipedia

Benzene

March 24, 2023

This article is about the chemical compound. For other uses, see Benzene (disambiguation).
Not to be confused with Petroleum benzine.

Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.[15]

Benzene
Geometry
Ball and stick model

Space-filling model
Names
IUPAC name
Benzene[1]
Other names
Benzol (historic/German)
Phenane
Phenylene hydride
Cyclohexa-1,3,5-triene; 1,3,5-Cyclohexatriene (theoretical resonance isomers)
[6]Annulene (not recommended[1])
Phene (historic)
Identifiers
  • 71-43-2 Y
3D model (JSmol)
  • Interactive image
ChEBI
  • CHEBI:16716 Y
ChEMBL
  • ChEMBL277500 Y
ChemSpider
  • 236 Y
ECHA InfoCard 100.000.685
EC Number
  • 200-753-7
KEGG
  • C01407 Y
  • 241
RTECS number
  • CY1400000
UNII
  • J64922108F Y
  • DTXSID3039242
  • InChI=1S/C6H6/c1-2-4-6-5-3-1/h1-6H Y
    Key: UHOVQNZJYSORNB-UHFFFAOYSA-N Y
  • c1ccccc1
Properties
C6H6
Molar mass 78.114 g·mol−1
Appearance Colorless liquid
Odor sweet aromatic
Density 0.8765(20) g/cm3[2]
Melting point 5.53 °C (41.95 °F; 278.68 K)
Boiling point 80.1 °C (176.2 °F; 353.2 K)
1.53 g/L (0 °C)
1.81 g/L (9 °C)
1.79 g/L (15 °C)[3][4][5]
1.84 g/L (30 °C)
2.26 g/L (61 °C)
3.94 g/L (100 °C)
21.7 g/kg (200 °C, 6.5 MPa)
17.8 g/kg (200 °C, 40 MPa)[6]
Solubility Soluble in alcohol, CHCl3, CCl4, diethyl ether, acetone, acetic acid[6]
Solubility in ethanediol 5.83 g/100 g (20 °C)
6.61 g/100 g (40 °C)
7.61 g/100 g (60 °C)[6]
Solubility in ethanol 20 °C, solution in ethanol:
1.2 mL/L (20% v/v)[7]
Solubility in acetone 20 °C, solution in aceton:
7.69 mL/L (38.46% v/v)
49.4 mL/L (62.5% v/v)[7]
Solubility in diethylene glycol 52 g/100 g (20 °C)[6]
log P 2.13
Vapor pressure 12.7 kPa (25 °C)
24.4 kPa (40 °C)
181 kPa (100 °C)[8]
Conjugate acid Benzenium[9]
Conjugate base Benzenide[10]
UV-vis (λmax) 255 nm
−54.8·10−6 cm3/mol
1.5011 (20 °C)
1.4948 (30 °C)[6]
Viscosity 0.7528 cP (10 °C)
0.6076 cP (25 °C)
0.4965 cP (40 °C)
0.3075 cP (80 °C)
Structure
Trigonal planar
0 D
Thermochemistry
134.8 J/mol·K
173.26 J/mol·K[8]
48.7 kJ/mol
-3267.6 kJ/mol[8]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 potential occupational carcinogen, flammable
GHS labelling:
[11]
Danger
H225, H302, H304, H305, H315, H319, H340, H350, H372, H410[11]
P201, P210, P301+P310, P305+P351+P338, P308+P313, P331[11]
NFPA 704 (fire diamond)
2
3
0
Flash point −11.63 °C (11.07 °F; 261.52 K)
497.78 °C (928.00 °F; 770.93 K)
Explosive limits 1.2–7.8%
Lethal dose or concentration (LD, LC):
80,8 mg/kg (rat, oral)[13]
44,000 ppm (rabbit, 30 min)
44,923 ppm (dog)
52,308 ppm (cat)
20,000 ppm (human, 5 min)[14]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1 ppm, ST 5 ppm[12]
REL (Recommended)
 Ca TWA 0.1 ppm ST 1 ppm[12]
IDLH (Immediate danger)
 500 ppm[12]
Safety data sheet (SDS) HMDB
Related compounds
Related compounds
 Toluene
Borazine
Supplementary data page
Benzene (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)

Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major industrial chemical, it finds limited use in consumer items because of its toxicity.

History

Discovery

The word "benzene" derives from "gum benzoin" (benzoin resin), an aromatic resin known since ancient times in Southeast Asia; and later to European pharmacists and perfumers in the 16th century via trade routes.[16] An acidic material was derived from benzoin by sublimation, and named "flowers of benzoin", or benzoic acid. The hydrocarbon derived from benzoic acid thus acquired the name benzin, benzol, or benzene.[17] Michael Faraday first isolated and identified benzene in 1825 from the oily residue derived from the production of illuminating gas, giving it the name bicarburet of hydrogen.[18][19] In 1833, Eilhard Mitscherlich produced it by distilling benzoic acid (from gum benzoin) and lime. He gave the compound the name benzin.[20] In 1836, the French chemist Auguste Laurent named the substance "phène";[21] this word has become the root of the English word "phenol", which is hydroxylated benzene, and "phenyl", the radical formed by abstraction of a hydrogen atom (free radical H•) from benzene.

  •  

    Kekulé's 1872 modification of his 1865 theory, illustrating rapid alternation of double bonds[note 1]

In 1845, Charles Blachford Mansfield, working under August Wilhelm von Hofmann, isolated benzene from coal tar.[22] Four years later, Mansfield began the first industrial-scale production of benzene, based on the coal-tar method.[23][24] Gradually, the sense developed among chemists that a number of substances were chemically related to benzene, comprising a diverse chemical family. In 1855, Hofmann used the word "aromatic" to designate this family relationship, after a characteristic property of many of its members.[25] In 1997, benzene was detected in deep space.[26]

Ring formula

Historic proposals of benzene structures
     
By Adolf Karl Ludwig Claus (1867)[27] By James Dewar (1869)[28] By Albert Ladenburg (1869)[29]
 
By August Kekulé (1865/1872)[30][31]
     
By Henry Edward Armstrong (1887)[32][33] By Adolf von Baeyer (1888)[34] By Friedrich Karl Johannes Thiele (1899)[35]

The empirical formula for benzene was long known, but its highly polyunsaturated structure, with just one hydrogen atom for each carbon atom, was challenging to determine. Archibald Scott Couper in 1858 and Johann Josef Loschmidt in 1861[36] suggested possible structures that contained multiple double bonds or multiple rings, but too little evidence was then available to help chemists decide on any particular structure.

In 1865, the German chemist Friedrich August Kekulé published a paper in French (for he was then teaching in Francophone Belgium) suggesting that the structure contained a ring of six carbon atoms with alternating single and double bonds. The next year he published a much longer paper in German on the same subject.[30][37] Kekulé used evidence that had accumulated in the intervening years—namely, that there always appeared to be only one isomer of any monoderivative of benzene, and that there always appeared to be exactly three isomers of every disubstituted derivative—now understood to correspond to the ortho, meta, and para patterns of arene substitution—to argue in support of his proposed structure.[38] Kekulé's symmetrical ring could explain these curious facts, as well as benzene's 1:1 carbon-hydrogen ratio.

The new understanding of benzene, and hence of all aromatic compounds, proved to be so important for both pure and applied chemistry that in 1890 the German Chemical Society organized an elaborate appreciation in Kekulé's honor, celebrating the twenty-fifth anniversary of his first benzene paper. Here Kekulé spoke of the creation of the theory. He said that he had discovered the ring shape of the benzene molecule after having a reverie or day-dream of a snake biting its own tail (this is a common symbol in many ancient cultures known as the Ouroboros or endless knot).[39] This vision, he said, came to him after years of studying the nature of carbon-carbon bonds. This was seven years after he had solved the problem of how carbon atoms could bond to up to four other atoms at the same time. Curiously, a similar, humorous depiction of benzene had appeared in 1886 in a pamphlet entitled Berichte der Durstigen Chemischen Gesellschaft (Journal of the Thirsty Chemical Society), a parody of the Berichte der Deutschen Chemischen Gesellschaft, only the parody had monkeys seizing each other in a circle, rather than snakes as in Kekulé's anecdote.[40] Some historians have suggested that the parody was a lampoon of the snake anecdote, possibly already well known through oral transmission even if it had not yet appeared in print.[17] Kekulé's 1890 speech[41] in which this anecdote appeared has been translated into English.[42] If the anecdote is the memory of a real event, circumstances mentioned in the story suggest that it must have happened early in 1862.[43]

In 1929, the cyclic nature of benzene was finally confirmed by the crystallographer Kathleen Lonsdale using X-ray diffraction methods.[44][45] Using large crystals of hexamethylbenzene, a benzene derivative with the same core of six carbon atoms, Lonsdale obtained diffraction patterns. Through calculating more than thirty parameters, Lonsdale demonstrated that the benzene ring could not be anything but a flat hexagon, and provided accurate distances for all carbon-carbon bonds in the molecule.[46]

Nomenclature

The German chemist Wilhelm Körner suggested the prefixes ortho-, meta-, para- to distinguish di-substituted benzene derivatives in 1867; however, he did not use the prefixes to distinguish the relative positions of the substituents on a benzene ring.[47][48] It was the German chemist Carl Gräbe who, in 1869, first used the prefixes ortho-, meta-, para- to denote specific relative locations of the substituents on a di-substituted aromatic ring (viz, naphthalene).[49] In 1870, the German chemist Viktor Meyer first applied Gräbe's nomenclature to benzene.[50]

Early applications

In the 19th and early 20th centuries, benzene was used as an after-shave lotion because of its pleasant smell.[citation needed] Prior to the 1920s, benzene was frequently used as an industrial solvent, especially for degreasing metal. As its toxicity became obvious, benzene was supplanted by other solvents, especially toluene (methylbenzene), which has similar physical properties but is not as carcinogenic.

In 1903, Ludwig Roselius popularized the use of benzene to decaffeinate coffee. This discovery led to the production of Sanka. This process was later discontinued. Benzene was historically used as a significant component in many consumer products such as liquid wrench, several paint strippers, rubber cements, spot removers, and other products. Manufacture of some of these benzene-containing formulations ceased in about 1950, although Liquid Wrench continued to contain significant amounts of benzene until the late 1970s.[51]

Occurrence

Trace amounts of benzene are found in petroleum and coal. It is a byproduct of the incomplete combustion of many materials. For commercial use, until World War II, much of benzene was obtained as a by-product of coke production (or "coke-oven light oil") for the steel industry. However, in the 1950s, increased demand for benzene, especially from the growing polymers industry, necessitated the production of benzene from petroleum. Today, most benzene comes from the petrochemical industry, with only a small fraction being produced from coal.[52] Benzene molecules have been detected on Mars.[53][54][55]

Structure

Main article: Aromaticity
 
The various representations of benzene.

X-ray diffraction shows that all six carbon-carbon bonds in benzene are of the same length, at 140 picometres (pm).[56] The C–C bond lengths are greater than a double bond (135 pm) but shorter than a single bond (147 pm). This intermediate distance is caused by electron delocalization: the electrons for C=C bonding are distributed equally between each of the six carbon atoms. Benzene has 6 hydrogen atoms, fewer than the corresponding parent alkane, hexane, which has 14. Benzene and cyclohexane have a similar structure, only the ring of delocalized electrons and the loss of one hydrogen per carbon distinguishes it from cyclohexane. The molecule is planar.[57] The molecular orbital description involves the formation of three delocalized π orbitals spanning all six carbon atoms, while the valence bond description involves a superposition of resonance structures.[58][59][60][61] It is likely that this stability contributes to the peculiar molecular and chemical properties known as aromaticity. To accurately reflect the nature of the bonding, benzene is often depicted with a circle inside a hexagonal arrangement of carbon atoms.

Derivatives of benzene occur sufficiently often as a component of organic molecules, so much so that the Unicode Consortium has allocated a symbol in the Miscellaneous Technical block with the code U+232C (⌬) to represent it with three double bonds,[62] and U+23E3 (⏣) for a delocalized version.[63]

Benzene derivatives

Main articles: Aromatic hydrocarbons and Alkylbenzenes

Many important chemical compounds are derived from benzene by replacing one or more of its hydrogen atoms with another functional group. Examples of simple benzene derivatives are phenol, toluene, and aniline, abbreviated PhOH, PhMe, and PhNH2, respectively. Linking benzene rings gives biphenyl, C6H5–C6H5. Further loss of hydrogen gives "fused" aromatic hydrocarbons, such as naphthalene, anthracene, phenanthrene, and pyrene. The limit of the fusion process is the hydrogen-free allotrope of carbon, graphite.

In heterocycles, carbon atoms in the benzene ring are replaced with other elements. The most important variations contain nitrogen. Replacing one CH with N gives the compound pyridine, C5H5N. Although benzene and pyridine are structurally related, benzene cannot be converted into pyridine. Replacement of a second CH bond with N gives, depending on the location of the second N, pyridazine, pyrimidine, or pyrazine.[64]

Production

Four chemical processes contribute to industrial benzene production: catalytic reforming, toluene hydrodealkylation, toluene disproportionation, and steam cracking etc. According to the ATSDR Toxicological Profile for benzene, between 1978 and 1981, catalytic reformates accounted for approximately 44–50% of the total U.S benzene production.[52]

Catalytic reforming

In catalytic reforming, a mixture of hydrocarbons with boiling points between 60 and 200 °C is blended with hydrogen gas and then exposed to a bifunctional platinum chloride or rhenium chloride catalyst at 500–525 °C and pressures ranging from 8–50 atm. Under these conditions, aliphatic hydrocarbons form rings and lose hydrogen to become aromatic hydrocarbons. The aromatic products of the reaction are then separated from the reaction mixture (or reformate) by extraction with any one of a number of solvents, including diethylene glycol or sulfolane, and benzene is then separated from the other aromatics by distillation. The extraction step of aromatics from the reformate is designed to produce aromatics with lowest non-aromatic components. Recovery of the aromatics, commonly referred to as BTX (benzene, toluene and xylene isomers), involves such extraction and distillation steps.

In similar fashion to this catalytic reforming, UOP and BP commercialized a method from LPG (mainly propane and butane) to aromatics.

Toluene hydrodealkylation

Toluene hydrodealkylation converts toluene to benzene. In this hydrogen-intensive process, toluene is mixed with hydrogen, then passed over a chromium, molybdenum, or platinum oxide catalyst at 500–650 °C and 20–60 atm pressure. Sometimes, higher temperatures are used instead of a catalyst (at the similar reaction condition). Under these conditions, toluene undergoes dealkylation to benzene and methane:

 

This irreversible reaction is accompanied by an equilibrium side reaction that produces biphenyl (aka diphenyl) at higher temperature:

2 C
6H
6 ⇌ H
2 + C
6H
5–C
6H
5

If the raw material stream contains much non-aromatic components (paraffins or naphthenes), those are likely decomposed to lower hydrocarbons such as methane, which increases the consumption of hydrogen.

A typical reaction yield exceeds 95%. Sometimes, xylenes and heavier aromatics are used in place of toluene, with similar efficiency.

This is often called "on-purpose" methodology to produce benzene, compared to conventional BTX (benzene-toluene-xylene) extraction processes.

Toluene disproportionation

Toluene disproportionation (TDP) is the conversion of toluene to benzene and xylene.

Given that demand for para-xylene (p-xylene) substantially exceeds demand for other xylene isomers, a refinement of the TDP process called Selective TDP (STDP) may be used. In this process, the xylene stream exiting the TDP unit is approximately 90% p-xylene. In some systems, even the benzene-to-xylenes ratio is modified to favor xylenes.

Steam cracking

Steam cracking is the process for producing ethylene and other alkenes from aliphatic hydrocarbons. Depending on the feedstock used to produce the olefins, steam cracking can produce a benzene-rich liquid by-product called pyrolysis gasoline. Pyrolysis gasoline can be blended with other hydrocarbons as a gasoline additive, or routed through an extraction process to recover BTX aromatics (benzene, toluene and xylenes).

Other methods

Although of no commercial significance, many other routes to benzene exist. Phenol and halobenzenes can be reduced with metals. Benzoic acid and its salts undergo decarboxylation to benzene. The reaction of the diazonium compound derived from aniline with hypophosphorus acid gives benzene. Alkyne trimerisation of acetylene gives benzene. Complete decarboxylation of mellitic acid gives benzene.

Uses

Benzene is used mainly as an intermediate to make other chemicals, above all ethylbenzene (and other alkylbenzenes), cumene, cyclohexane, and nitrobenzene. In 1988 it was reported that two-thirds of all chemicals on the American Chemical Society's lists contained at least one benzene ring.[65] More than half of the entire benzene production is processed into ethylbenzene, a precursor to styrene, which is used to make polymers and plastics like polystyrene. Some 20% of the benzene production is used to manufacture cumene, which is needed to produce phenol and acetone for resins and adhesives. Cyclohexane consumes around 10% of the world's benzene production; it is primarily used in the manufacture of nylon fibers, which are processed into textiles and engineering plastics. Smaller amounts of benzene are used to make some types of rubbers, lubricants, dyes, detergents, drugs, explosives, and pesticides. In 2013, the biggest consumer country of benzene was China, followed by the USA. Benzene production is currently expanding in the Middle East and in Africa, whereas production capacities in Western Europe and North America are stagnating.[66]

Toluene is now often used as a substitute for benzene, for instance as a fuel additive. The solvent-properties of the two are similar, but toluene is less toxic and has a wider liquid range. Toluene is also processed into benzene.[67]

BenzeneEthylbenzeneCumeneCyclohexaneAnilineChlorobenzeneAcetonePhenolStyreneBisphenol AAdipic acidCaprolactamPolystyrenePolycarbonateEpoxy resinPhenolic resinNylon 6-6Nylon 6 
Major commodity chemicals and polymers derived from benzene. Clicking on the image loads the appropriate article

Component of gasoline

As a gasoline (petrol) additive, benzene increases the octane rating and reduces knocking. As a consequence, gasoline often contained several percent benzene before the 1950s, when tetraethyl lead replaced it as the most widely used antiknock additive. With the global phaseout of leaded gasoline, benzene has made a comeback as a gasoline additive in some nations. In the United States, concern over its negative health effects and the possibility of benzene entering the groundwater has led to stringent regulation of gasoline's benzene content, with limits typically around 1%.[68] European petrol specifications now contain the same 1% limit on benzene content. The United States Environmental Protection Agency introduced new regulations in 2011 that lowered the benzene content in gasoline to 0.62%.[69]

In many European languages, the word for petroleum or gasoline is an exact cognate of "benzene".[citation needed]

Reactions

The most common reactions of benzene involve substitution of a proton by other groups.[70] Electrophilic aromatic substitution is a general method of derivatizing benzene. Benzene is sufficiently nucleophilic that it undergoes substitution by acylium ions and alkyl carbocations to give substituted derivatives.

 
Electrophilic aromatic substitution of benzene

The most widely practiced example of this reaction is the ethylation of benzene.

 

Approximately 24,700,000 tons were produced in 1999.[71] Highly instructive but of far less industrial significance is the Friedel-Crafts alkylation of benzene (and many other aromatic rings) using an alkyl halide in the presence of a strong Lewis acid catalyst. Similarly, the Friedel-Crafts acylation is a related example of electrophilic aromatic substitution. The reaction involves the acylation of benzene (or many other aromatic rings) with an acyl chloride using a strong Lewis acid catalyst such as aluminium chloride or Iron(III) chloride.

 
Friedel-Crafts acylation of benzene by acetyl chloride

Sulfonation, chlorination, nitration

Using electrophilic aromatic substitution, many functional groups are introduced onto the benzene framework. Sulfonation of benzene involves the use of oleum, a mixture of sulfuric acid with sulfur trioxide. Sulfonated benzene derivatives are useful detergents. In nitration, benzene reacts with nitronium ions (NO2+), which is a strong electrophile produced by combining sulfuric and nitric acids. Nitrobenzene is the precursor to aniline. Chlorination is achieved with chlorine to give chlorobenzene in the presence of a Lewis acid catalyst such as aluminium tri-chloride.

Hydrogenation

Via hydrogenation, benzene and its derivatives convert to cyclohexane and derivatives. This reaction is achieved by the use of high pressures of hydrogen in the presence of heterogeneous catalysts, such as finely divided nickel. Whereas alkenes can be hydrogenated near room temperatures, benzene and related compounds are more reluctant substrates, requiring temperatures >100 °C. This reaction is practiced on a large scale industrially. In the absence of the catalyst, benzene is impervious to hydrogen. Hydrogenation cannot be stopped to give cyclohexene or cyclohexadienes as these are superior substrates. Birch reduction, a non catalytic process, however selectively hydrogenates benzene to the diene.

Metal complexes

Benzene is an excellent ligand in the organometallic chemistry of low-valent metals. Important examples include the sandwich and half-sandwich complexes, respectively, Cr(C6H6)2 and [RuCl2(C6H6)]2.

Health effects

 
A bottle of benzene. The warnings show benzene is a toxic and flammable liquid.

Benzene is classified as a carcinogen, which increases the risk of cancer and other illnesses, and is also a notorious cause of bone marrow failure. Substantial quantities of epidemiologic, clinical, and laboratory data link benzene to aplastic anemia, acute leukemia, bone marrow abnormalities and cardiovascular disease.[72][73][74] The specific hematologic malignancies that benzene is associated with include: acute myeloid leukemia (AML), aplastic anemia, myelodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), and chronic myeloid leukemia (CML).[75]

The American Petroleum Institute (API) stated in 1948 that "it is generally considered that the only absolutely safe concentration for benzene is zero".[76] There is no safe exposure level; even tiny amounts can cause harm.[77] The US Department of Health and Human Services (DHHS) classifies benzene as a human carcinogen. Long-term exposure to excessive levels of benzene in the air causes leukemia, a potentially fatal cancer of the blood-forming organs. In particular, acute myeloid leukemia or acute nonlymphocytic leukemia (AML & ANLL) is caused by benzene.[78] IARC rated benzene as "known to be carcinogenic to humans" (Group 1).

As benzene is ubiquitous in gasoline and hydrocarbon fuels that are in use everywhere, human exposure to benzene is a global health problem. Benzene targets the liver, kidney, lung, heart and brain and can cause DNA strand breaks and chromosomal damage. Benzene causes cancer in animals including humans. Benzene has been shown to cause cancer in both sexes of multiple species of laboratory animals exposed via various routes.[79][80]

Exposure to benzene

According to the Agency for Toxic Substances and Disease Registry (ATSDR) (2007), benzene is both a synthetically-made and naturally occurring chemical from processes that include: volcanic eruptions, wild fires, synthesis of chemicals such as phenol, production of synthetic fibers, and fabrication of rubbers, lubricants, pesticides, medications, and dyes. The major sources of benzene exposure are tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions; however, ingestion and dermal absorption of benzene can also occur through contact with contaminated water. Benzene is hepatically metabolized and excreted in the urine. Measurement of air and water levels of benzene is accomplished through collection via activated charcoal tubes, which are then analyzed with a gas chromatograph. The measurement of benzene in humans can be accomplished via urine, blood, and breath tests; however, all of these have their limitations because benzene is rapidly metabolized in the human body.[81]

Exposure to benzene may lead progressively to aplastic anemia, leukaemia, and multiple myeloma.[82]

OSHA regulates levels of benzene in the workplace.[83] The maximum allowable amount of benzene in workroom air during an 8-hour workday, 40-hour workweek is 1 ppm. As benzene can cause cancer, NIOSH recommends that all workers wear special breathing equipment when they are likely to be exposed to benzene at levels exceeding the recommended (8-hour) exposure limit of 0.1 ppm.[84]

Benzene exposure limits

The United States Environmental Protection Agency has set a maximum contaminant level for benzene in drinking water at 0.0005 mg/L (5 ppb), as promulgated via the U.S. National Primary Drinking Water Regulations.[85] This regulation is based on preventing benzene leukemogenesis. The maximum contaminant level goal (MCLG), a nonenforceable health goal that would allow an adequate margin of safety for the prevention of adverse effects, is zero benzene concentration in drinking water. The EPA requires that spills or accidental releases into the environment of 10 pounds (4.5 kg) or more of benzene be reported.

The U.S. Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit of 1 part of benzene per million parts of air (1 ppm) in the workplace during an 8-hour workday, 40-hour workweek. The short term exposure limit for airborne benzene is 5 ppm for 15 minutes.[86] These legal limits were based on studies demonstrating compelling evidence of health risk to workers exposed to benzene. The risk from exposure to 1 ppm for a working lifetime has been estimated as 5 excess leukemia deaths per 1,000 employees exposed. (This estimate assumes no threshold for benzene's carcinogenic effects.) OSHA has also established an action level of 0.5 ppm to encourage even lower exposures in the workplace.[87]

The U.S. National Institute for Occupational Safety and Health (NIOSH) revised the Immediately Dangerous to Life and Health (IDLH) concentration for benzene to 500 ppm. The current NIOSH definition for an IDLH condition, as given in the NIOSH Respirator Selection Logic, is one that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment.[88] The purpose of establishing an IDLH value is (1) to ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment and (2) is considered a maximum level above which only a highly reliable breathing apparatus providing maximum worker protection is permitted.[88][89] In September 1995, NIOSH issued a new policy for developing recommended exposure limits (RELs) for substances, including carcinogens. As benzene can cause cancer, NIOSH recommends that all workers wear special breathing equipment when they are likely to be exposed to benzene at levels exceeding the REL (10-hour) of 0.1 ppm.[90] The NIOSH short-term exposure limit (STEL – 15 min) is 1 ppm.

American Conference of Governmental Industrial Hygienists (ACGIH) adopted Threshold Limit Values (TLVs) for benzene at 0.5 ppm TWA and 2.5 ppm STEL.[citation needed]

Toxicology

Biomarkers of exposure

Several tests can determine exposure to benzene. Benzene itself can be measured in breath, blood or urine, but such testing is usually limited to the first 24 hours post-exposure due to the relatively rapid removal of the chemical by exhalation or biotransformation. Most people in developed countries have measureable baseline levels of benzene and other aromatic petroleum hydrocarbons in their blood. In the body, benzene is enzymatically converted to a series of oxidation products including muconic acid, phenylmercapturic acid, phenol, catechol, hydroquinone and 1,2,4-trihydroxybenzene. Most of these metabolites have some value as biomarkers of human exposure, since they accumulate in the urine in proportion to the extent and duration of exposure, and they may still be present for some days after exposure has ceased. The current ACGIH biological exposure limits for occupational exposure are 500 μg/g creatinine for muconic acid and 25 μg/g creatinine for phenylmercapturic acid in an end-of-shift urine specimen.[91][92][93][94]

Biotransformations

Even if it is not a common substrate for metabolism, benzene can be oxidized by both bacteria and eukaryotes. In bacteria, dioxygenase enzyme can add an oxygen to the ring, and the unstable product is immediately reduced (by NADH) to a cyclic diol with two double bonds, breaking the aromaticity. Next, the diol is newly reduced by NADH to catechol. The catechol is then metabolized to acetyl CoA and succinyl CoA, used by organisms mainly in the citric acid cycle for energy production.

The pathway for the metabolism of benzene is complex and begins in the liver. Several enzymes are involved. These include cytochrome P450 2E1 (CYP2E1), quinine oxidoreductase (NQ01 or DT-diaphorase or NAD(P)H dehydrogenase (quinone 1)), GSH, and myeloperoxidase (MPO). CYP2E1 is involved at multiple steps: converting benzene to oxepin (benzene oxide), phenol to hydroquinone, and hydroquinone to both benzenetriol and catechol. Hydroquinone, benzenetriol and catechol are converted to polyphenols. In the bone marrow, MPO converts these polyphenols to benzoquinones. These intermediates and metabolites induce genotoxicity by multiple mechanisms including inhibition of topoisomerase II (which maintains chromosome structure), disruption of microtubules (which maintains cellular structure and organization), generation of oxygen free radicals (unstable species) that may lead to point mutations, increasing oxidative stress, inducing DNA strand breaks, and altering DNA methylation (which can affect gene expression). NQ01 and GSH shift metabolism away from toxicity. NQ01 metabolizes benzoquinone toward polyphenols (counteracting the effect of MPO). GSH is involved with the formation of phenylmercapturic acid.[75][95]

Genetic polymorphisms in these enzymes may induce loss of function or gain of function. For example, mutations in CYP2E1 increase activity and result in increased generation of toxic metabolites. NQ01 mutations result in loss of function and may result in decreased detoxification. Myeloperoxidase mutations result in loss of function and may result in decreased generation of toxic metabolites. GSH mutations or deletions result in loss of function and result in decreased detoxification. These genes may be targets for genetic screening for susceptibility to benzene toxicity.[96]

Molecular toxicology

The paradigm of toxicological assessment of benzene is shifting towards the domain of molecular toxicology as it allows understanding of fundamental biological mechanisms in a better way. Glutathione seems to play an important role by protecting against benzene-induced DNA breaks and it is being identified as a new biomarker for exposure and effect.[97] Benzene causes chromosomal aberrations in the peripheral blood leukocytes and bone marrow explaining the higher incidence of leukemia and multiple myeloma caused by chronic exposure. These aberrations can be monitored using fluorescent in situ hybridization (FISH) with DNA probes to assess the effects of benzene along with the hematological tests as markers of hematotoxicity.[98] Benzene metabolism involves enzymes coded for by polymorphic genes. Studies have shown that genotype at these loci may influence susceptibility to the toxic effects of benzene exposure. Individuals carrying variant of NAD(P)H:quinone oxidoreductase 1 (NQO1), microsomal epoxide hydrolase (EPHX) and deletion of the glutathione S-transferase T1 (GSTT1) showed a greater frequency of DNA single-stranded breaks.[99]

Biological oxidation and carcinogenic activity

One way of understanding the carcinogenic effects of benzene is by examining the products of biological oxidation. Pure benzene, for example, oxidizes in the body to produce an epoxide, benzene oxide, which is not excreted readily and can interact with DNA to produce harmful mutations.

Routes of exposure

Inhalation

Outdoor air may contain low levels of benzene from automobile service stations, wood smoke, tobacco smoke, the transfer of gasoline, exhaust from motor vehicles, and industrial emissions.[100] About 50% of the entire nationwide (United States) exposure to benzene results from smoking tobacco or from exposure to tobacco smoke.[101] After smoking 32 cigarettes per day, the smoker would take in about 1.8 milligrams (mg) of benzene. This amount is about 10 times the average daily intake of benzene by nonsmokers.[102]

Inhaled benzene is primarily expelled unchanged through exhalation. In a human study 16.4 to 41.6% of retained benzene was eliminated through the lungs within five to seven hours after a two- to three-hour exposure to 47 to 110 ppm and only 0.07 to 0.2% of the remaining benzene was excreted unchanged in the urine. After exposure to 63 to 405 mg/m3 of benzene for 1 to 5 hours, 51 to 87% was excreted in the urine as phenol over a period of 23 to 50 hours. In another human study, 30% of absorbed dermally applied benzene, which is primarily metabolized in the liver, was excreted as phenol in the urine.[103]

Exposure from soft drinks

Main article: Benzene in soft drinks

Under specific conditions and in the presence of other chemicals benzoic acid (a preservative) and ascorbic acid (Vitamin C) may interact to produce benzene. In March 2006, the official Food Standards Agency in United Kingdom conducted a survey of 150 brands of soft drinks. It found that four contained benzene levels above World Health Organization limits. The affected batches were removed from sale. Similar problems were reported by the FDA in the United States.[104]

Contamination of water supply

In 2005, the water supply to the city of Harbin in China with a population of almost nine million people, was cut off because of a major benzene exposure.[105] Benzene leaked into the Songhua River, which supplies drinking water to the city, after an explosion at a China National Petroleum Corporation (CNPC) factory in the city of Jilin on 13 November 2005.

When plastic water pipes are subject to high heat, the water may be contaminated with benzene.[106]

Genocide

The Nazis used benzene administered via injection as one of their many methods for killing.[107][108]

See also

Explanatory notes

  1. ^ Critics pointed out a problem with Kekulé's original (1865) structure for benzene: Whenever benzene underwent substitution at the ortho position, two distinguishable isomers should have resulted, depending on whether a double bond or a single bond existed between the carbon atoms to which the substituents were attached; however, no such isomers were observed. In 1872, Kekulé suggested that benzene had two complementary structures and that these forms rapidly interconverted, so that if there were a double bond between any pair of carbon atoms at one instant, that double bond would become a single bond at the next instant (and vice versa). To provide a mechanism for the conversion process, Kekulé proposed that the valency of an atom is determined by the frequency with which it collided with its neighbors in a molecule. As the carbon atoms in the benzene ring collided with each other, each carbon atom would collide twice with one neighbor during a given interval and then twice with its other neighbor during the next interval. Thus, a double bond would exist with one neighbor during the first interval and with the other neighbor during the next interval. Therefore, between the carbon atoms of benzene there were no fixed (i.e., constant) and distinct single or double bonds; instead, the bonds between the carbon atoms were identical. See pages 86–89 2020-03-20 at the Wayback Machine of Auguste Kekulé (1872) "Ueber einige Condensationsprodukte des Aldehyds" (On some condensation products of aldehydes), Liebig's Annalen der Chemie und Pharmacie, 162(1): 77–124, 309–320. From p. 89: "Das einfachste Mittel aller Stöße eines Kohlenstoffatoms ergiebt sich aus der Summe der Stöße der beiden ersten Zeiteinheiten, die sich dann periodisch wiederholen. … man sieht daher, daß jedes Kohlenstoffatom mit den beiden anderen, … daß diese Verschiedenheit nur eine scheinbare, aber keine wirkliche ist." (The simplest average of all the collisions of a carbon atom [in benzene] comes from the sum of the collisions during the first two units of time, which then periodically repeat. … thus one sees that each carbon atom collides equally often with the two others against which it bumps, [and] thus stands in exactly the same relation with its two neighbors. The usual structural formula for benzene expresses, of course, only the collisions that occur during one unit of time, thus during one phase, and so one is led to the view [that] doubly substituted derivatives [of benzene] must be different at positions 1,2 and 1,6 [of the benzene ring]. If the idea [that was] just presented—or a similar one—can be regarded as correct, then [it] follows therefrom that this difference [between the bonds at positions 1,2 and 1,6] is only an apparent [one], not a real [one].)

References

  1. ^ a b Favre, Henri A.; Powell, Warren H. (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. pp. 10, 22, 204, 494, 577. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
  2. ^ Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  3. ^ Arnold, D.; Plank, C.; Erickson, E.; Pike, F. (1958). "Solubility of Benzene in Water". Industrial & Engineering Chemistry Chemical & Engineering Data Series. 3 (2): 253–256. doi:10.1021/i460004a016.
  4. ^ Breslow, R.; Guo, T. (1990). "Surface tension measurements show that chaotropic salting-in denaturants are not just water-structure breakers". Proceedings of the National Academy of Sciences of the United States of America. 87 (1): 167–9. Bibcode:1990PNAS...87..167B. doi:10.1073/pnas.87.1.167. PMC 53221. PMID 2153285.
  5. ^ Coker, A. Kayode; Ludwig, Ernest E. (2007). Ludwig's Applied Process Design for Chemical And Petrochemical Plants. Vol. 1. Elsevier. p. 114. ISBN 978-0-7506-7766-0. from the original on 2016-03-12. Retrieved 2012-05-31.
  6. ^ a b c d e "Benzol". from the original on 2014-05-29. Retrieved 2014-05-29.
  7. ^ a b Atherton Seidell; William F. Linke (1952). Solubilities of Inorganic and Organic Compounds: A Compilation of Solubility Data from the Periodical Literature. Supplement. Van Nostrand. from the original on 2020-03-11. Retrieved 2015-06-27.
  8. ^ a b c Benzene in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-05-29)
  9. ^ "Benzenium (CID 12533897". PubChem. February 8, 2007. Retrieved September 18, 2022.
  10. ^ "Benzenide (CID 5150480)". PubChem. June 24, 2005. Retrieved September 18, 2022.
  11. ^ a b c Sigma-Aldrich Co., Benzene 2016-12-01 at the Wayback Machine. Retrieved on 2014-05-29.
  12. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0049". National Institute for Occupational Safety and Health (NIOSH).
  13. ^ Benzene, toxicity
  14. ^ "Benzene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  15. ^ "Benzene - an overview | ScienceDirect Topics". www.sciencedirect.com. from the original on 2021-02-08. Retrieved 2020-11-25.
  16. ^ The word "benzoin" is derived from the Arabic expression "luban jawi", or "frankincense of Java". Morris, Edwin T. (1984). Fragrance: The Story of Perfume from Cleopatra to Chanel. Charles Scribner's Sons. p. 101. ISBN 978-0684181950.
  17. ^ a b Rocke, A. J. (1985). "Hypothesis and Experiment in the Early Development of Kekule's Benzene Theory". Annals of Science. 42 (4): 355–81. doi:10.1080/00033798500200411.
  18. ^ Faraday, M. (1825). "On new compounds of carbon and hydrogen, and on certain other products obtained during the decomposition of oil by heat". Philosophical Transactions of the Royal Society. 115: 440–466. doi:10.1098/rstl.1825.0022. JSTOR 107752. from the original on 2020-11-21. Retrieved 2012-01-15. On pages 443–450, Faraday discusses "bicarburet of hydrogen" (benzene). On pages 449–450, he shows that benzene's empirical formula is C6H6, although he doesn't realize it because he (like most chemists at that time) used the wrong atomic mass for carbon (6 instead of 12).
  19. ^ Kaiser, R. (1968). "Bicarburet of Hydrogen. Reappraisal of the Discovery of Benzene in 1825 with the Analytical Methods of 1968". Angewandte Chemie International Edition in English. 7 (5): 345–350. doi:10.1002/anie.196803451.
  20. ^ Mitscherlich, E. (1834). "Über das Benzol und die Säuren der Oel- und Talgarten" [On benzol and oily and fatty types of acids]. Annalen der Pharmacie. 9 (1): 39–48. doi:10.1002/jlac.18340090103. from the original on 2015-11-23. Retrieved 2015-06-27. In a footnote on page 43, Liebig, the journal's editor, suggested changing Mitscherlich's original name for benzene (namely, "benzin") to "benzol", because the suffix "-in" suggested that it was an alkaloid (e.g., Chinin (quinine)), which benzene isn't, whereas the suffix "-ol" suggested that it was oily, which benzene is. Thus on page 44, Mitscherlich states: "Da diese Flüssigkeit aus der Benzoësäure gewonnen wird, und wahrscheinlich mit den Benzoylverbindungen im Zusammenhang steht, so gibt man ihr am besten den Namen Benzol, da der Name Benzoïn schon für die mit dem Bittermandelöl isomerische Verbindung von Liebig und Wöhler gewählt worden ist." (Since this liquid [benzene] is obtained from benzoic acid and probably is related to benzoyl compounds, the best name for it is "benzol", since the name "benzoïn" has already been chosen, by Liebig and Wöhler, for the compound that's isomeric with the oil of bitter almonds [benzaldehyde].)
  21. ^ Laurent, Auguste (1836) "Sur la chlorophénise et les acides chlorophénisique et chlorophénèsique," Annales de Chemie et de Physique, vol. 63, pp. 27–45, see p. 44 2015-03-20 at the Wayback Machine: "Je donne le nom de phène au radical fondamental des acides précédens (φαινω, j'éclaire), puisque la benzine se trouve dans le gaz de l'éclairage." (I give the name of "phène" (φαινω, I illuminate) to the fundamental radical of the preceding acids, because benzene is found in illuminating gas.)
  22. ^ Hofmann, A. W. (1845). "Ueber eine sichere Reaction auf Benzol" [On a reliable test for benzene]. Annalen der Chemie und Pharmacie (in German). 55 (2): 200–205, especially 204–205. doi:10.1002/jlac.18450550205. from the original on 2015-11-22.
  23. ^ Mansfield Charles Blachford (1849). "Untersuchung des Steinkohlentheers". Annalen der Chemie und Pharmacie. 69 (2): 162–180. doi:10.1002/jlac.18490690203. from the original on 2015-10-27. Retrieved 2015-06-27.
  24. ^ Charles Mansfield filed for (November 11, 1847) and received (May 1848) a patent (no. 11,960) for the fractional distillation of coal tar.
  25. ^ Hoffman, Augustus W. (1856). "On insolinic acid". Proceedings of the Royal Society. 8: 1–3. doi:10.1098/rspl.1856.0002. The existence and mode of formation of insolinic acid prove that to the series of monobasic aromatic acids, Cn2Hn2-8O4, the lowest known term of which is benzoic acid, … . [Note: The empirical formulas of organic compounds that appear in Hofmann's article (p. 3) are based upon an atomic mass of carbon of 6 (instead of 12) and an atomic mass of oxygen of 8 (instead of 16).]
  26. ^ Cernicharo, José; et al. (1997), "Infrared Space Observatory's Discovery of C4H2, C6H2, and Benzene in CRL 618", Astrophysical Journal Letters, 546 (2): L123–L126, Bibcode:2001ApJ...546L.123C, doi:10.1086/318871
  27. ^ Claus, Adolph K.L. (1867) "Theoretische Betrachtungen und deren Anwendungen zur Systematik der organischen Chemie" (Theoretical considerations and their applications to the classification scheme of organic chemistry), Berichte über die Verhandlungen der Naturforschenden Gesellschaft zu Freiburg im Breisgau (Reports of the Proceedings of the Scientific Society of Freiburg in Breisgau), 4 : 116–381. In the section Aromatischen Verbindungen (aromatic compounds), pp. 315–347, Claus presents Kekulé's hypothetical structure for benzene (p. 317), presents objections to it, presents an alternative geometry (p. 320), and concludes that his alternative is correct (p. 326). See also figures on p. 354 or p. 379.
  28. ^ Dewar James (1869). "On the oxidation of phenyl alcohol, and a mechanical arrangement adapted to illustrate structure in the non-saturated hydrocarbons". Proceedings of the Royal Society of Edinburgh. 6: 82–86. doi:10.1017/S0370164600045387. from the original on 2015-11-24. Retrieved 2015-06-27.
  29. ^ Ladenburg Albert (1869). "Bemerkungen zur aromatischen Theorie" [Observations on the aromatic theory]. Berichte der Deutschen Chemischen Gesellschaft. 2: 140–142. doi:10.1002/cber.18690020171. from the original on 2015-11-22. Retrieved 2015-06-27.
  30. ^ a b Kekulé, F. A. (1865). "Sur la constitution des substances aromatiques". Bulletin de la Société Chimique de Paris. 3: 98–110. from the original on 2015-11-14. Retrieved 2015-06-27. On p. 100, Kekulé suggests that the carbon atoms of benzene could form a "chaîne fermée" (a closed chain, a loop).
  31. ^ Aug. Kekulé (1872), "Ueber einige Condensationsproducte des Aldehyds" (PDF), Annalen der Chemie und Pharmacie (in German), vol. 162, no. 1, pp. 77–124, doi:10.1002/jlac.18721620110
  32. ^ Armstrong Henry E (1887). "An explanation of the laws which govern substitution in the case of benzenoid compounds". Journal of the Chemical Society. 51: 258–268 [264]. doi:10.1039/ct8875100258. from the original on 2015-10-22. Retrieved 2015-06-27.
  33. ^ In his 1890 paper, Armstrong represented benzene nuclei within polycyclic benzenoids by placing inside the benzene nuclei a letter "C", an abbreviation of the word "centric". Centric affinities (i.e., bonds) acted within a designated cycle of carbon atoms. From p. 102: " … benzene, according to this view, may be represented by a double ring, in fact." See: The use of a circle to denote a benzene nucleus first appeared in:
    • Armit, James Wilson; Robinson, Robert (1925). "Polynuclear heterocyclic aromatic types. Part II. Some anhydronium bases". Journal of the Chemical Society, Transactions. 127: 1604–1618. doi:10.1039/ct9252701604.
    A history of the determination of benzene's structure is recounted in:
    • Balaban, Alexandru T.; Schleyer, Paul v. R.; Rzepa, Henry S. (2005). "Crocker, Not Armit and Robinson, Begat the Six Aromatic Electrons". Chemical Reviews. 105 (10): 3436–3447. doi:10.1021/cr0300946. PMID 16218557.
  34. ^ Adolf Baeyer (1888), "Über die Constitution des Benzols", Justus Liebigs Annalen der Chemie (in German), vol. 245, no. 1–2, pp. 103–190, doi:10.1002/jlac.18882450110
  35. ^ Thiele, Johannes (1899) "Zur Kenntnis der ungesättigten Verbindungen" (On our knowledge of unsaturated compounds), Justus Liebig’s Annalen der Chemie306: 87–142; see: "VIII. Die aromatischen Verbindungen. Das Benzol." (VIII. The aromatic compounds. Benzene.), pp. 125–129. 2020-03-10 at the Wayback Machine See further: Thiele (1901) "Zur Kenntnis der ungesättigen Verbindungen," 2021-12-26 at the Wayback Machine Justus Liebig’s Annalen der Chemie, 319: 129–143.
  36. ^ Loschmidt, J. (1861). Chemische Studien (in German). Vienna, Austria-Hungary: Carl Gerold's Sohn. pp. 30, 65. from the original on 2016-05-07. Retrieved 2015-06-27.
  37. ^ Kekulé, F. A. (1866). "Untersuchungen über aromatische Verbindungen (Investigations of aromatic compounds)". Liebigs Annalen der Chemie und Pharmacie. 137 (2): 129–36. doi:10.1002/jlac.18661370202. from the original on 2021-12-26. Retrieved 2021-12-25.
  38. ^ Rocke, A. J. (2010). Image and Reality: Kekule, Kopp, and the Scientific Imagination. University of Chicago Press. pp. 186–227. ISBN 978-0226723358. from the original on 2020-07-27. Retrieved 2020-05-15.
  39. ^ Read, John (1995). From alchemy to chemistry. New York: Dover Publications. pp. 179–180. ISBN 9780486286907.
  40. ^ English translation Wilcox, David H.; Greenbaum, Frederick R. (1965). "Kekule's benzene ring theory: A subject for lighthearted banter". Journal of Chemical Education. 42 (5): 266–67. Bibcode:1965JChEd..42..266W. doi:10.1021/ed042p266.
  41. ^ Kekulé, F. A. (1890). "Benzolfest: Rede". Berichte der Deutschen Chemischen Gesellschaft. 23: 1302–11. doi:10.1002/cber.189002301204. from the original on 2007-05-16. Retrieved 2007-03-12.
  42. ^ Benfey O. T. (1958). "August Kekulé and the Birth of the Structural Theory of Organic Chemistry in 1858". Journal of Chemical Education. 35 (1): 21–23. Bibcode:1958JChEd..35...21B. doi:10.1021/ed035p21.
  43. ^ Gillis Jean (1966). "Auguste Kekulé et son oeuvre, réalisée à Gand de 1858 à 1867". Mémoires de la Classe des Sciences - Académie Royale des Sciences, des Lettres et des Beaux-arts de Belgique. 37 (1): 1–40.
  44. ^ Lonsdale, K. (1929). "The Structure of the Benzene Ring in Hexamethylbenzene". Proceedings of the Royal Society. 123A (792): 494–515. Bibcode:1929RSPSA.123..494L. doi:10.1098/rspa.1929.0081.
  45. ^ Lonsdale, K. (1931). "An X-Ray Analysis of the Structure of Hexachlorobenzene, Using the Fourier Method". Proceedings of the Royal Society. 133A (822): 536–553. Bibcode:1931RSPSA.133..536L. doi:10.1098/rspa.1931.0166. from the original on 2021-03-19. Retrieved 2007-03-12.
  46. ^ Ramos-Figueroa, Josseline (2021-05-21). "Meet Kathleen Lonsdale, the physicist and prison reformer who cracked benzene's code". Massive Science. Retrieved 2022-03-01.
  47. ^ Wilhelm Körner (1867) "Faits pour servir à la détermination du lieu chimique dans la série aromatique" 2017-07-07 at the Wayback Machine (Facts to be used in determining chemical location in the aromatic series), Bulletins de l'Académie royale des sciences, des lettres et des beaux-arts de Belgique, 2nd series, 24 : 166–185; see especially p. 169. From p. 169: "On distingue facilement ces trois séries, dans lesquelles les dérivés bihydroxyliques ont leurs terms correspondants, par les préfixes ortho-, para- et mêta-." (One easily distinguishes these three series – in which the dihydroxy derivatives have their corresponding terms – by the prefixes ortho-, para- and meta-.)
  48. ^ Hermann von Fehling, ed., Neues Handwörterbuch der Chemie [New concise dictionary of chemistry] (Braunschweig, Germany: Friedrich Vieweg und Sohn, 1874), vol. 1, p. 1142.
  49. ^ Graebe (1869) "Ueber die Constitution des Naphthalins" Archived 2015-11-28 at archive.today (On the structure of naphthalene), Annalen der Chemie und Pharmacie, 149 : 20–28; see especially p. 26.
  50. ^ Victor Meyer (1870) "Untersuchungen über die Constitution der zweifach-substituirten Benzole" Archived 2015-10-23 at archive.today (Investigations into the structure of di-substituted benzenes), Annalen der Chemie und Pharmacie, 156 : 265–301; see especially pp. 299–300.
  51. ^ Williams, P.R.D.; Knutsen, J.S.; Atkinson, C.; Madl, A.K.; Paustenbach, D.J. (2007). "Airborne Concentrations of Benzene Associated with the Historical Use of Some Formulations of Liquid Wrench". Journal of Occupational and Environmental Hygiene. 4 (8): 547–561. doi:10.1080/15459620701446642. PMID 17558801. S2CID 32311057.
  52. ^ a b Hillis O. Folkins (2005). "Benzene". Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_475. ISBN 978-3527306732.
  53. ^ Chang, Kenneth (June 7, 2018). "Life on Mars? Rover's Latest Discovery Puts It 'On the Table'". The New York Times. from the original on May 28, 2019. Retrieved June 8, 2018. The identification of organic molecules in rocks on the red planet does not necessarily point to life there, past or present, but does indicate that some of the building blocks were present.
  54. ^ ten Kate, Inge Loes (June 8, 2018). "Organic molecules on Mars". Science. 360 (6393): 1068–1069. Bibcode:2018Sci...360.1068T. doi:10.1126/science.aat2662. PMID 29880670. S2CID 46952468.
  55. ^ Eigenbrode, Jennifer L.; et al. (June 8, 2018). "Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars" (PDF). Science. 360 (6393): 1096–1101. Bibcode:2018Sci...360.1096E. doi:10.1126/science.aas9185. PMID 29880683. S2CID 46983230. (PDF) from the original on August 25, 2021. Retrieved January 4, 2021.
  56. ^ Bacon, G. E.; Curry, N.; Wilson, S. (May 12, 1964). "A Crystallographic Study of Solid Benzene by Neutron Diffraction". Proceedings of the Royal Society of London, Series A. 279 (1376): 98–110. Bibcode:1964RSPSA.279...98B. doi:10.1098/rspa.1964.0092. ISSN 2053-9169. JSTOR 2414835. S2CID 94432897.
  57. ^ Moran D, Simmonett AC, Leach FE, Allen WD, Schleyer PV, Schaefer HF (2006). "Popular Theoretical Methods Predict Benzene and Arenes To Be Nonplanar". Journal of the American Chemical Society. 128 (29): 9342–3. doi:10.1021/ja0630285. PMID 16848464.
  58. ^ Cooper, David L.; Gerratt, Joseph; Raimondi, Mario (1986). "The electronic structure of the benzene molecule". Nature. 323 (6090): 699–701. Bibcode:1986Natur.323..699C. doi:10.1038/323699a0. S2CID 24349360.
  59. ^ Pauling, Linus (1987). "Electronic structure of the benzene molecule". Nature. 325 (6103): 396. Bibcode:1987Natur.325..396P. doi:10.1038/325396d0. S2CID 4261220.
  60. ^ Messmer, Richard P.; Schultz, Peter A. (1987). "The electronic structure of the benzene molecule". Nature. 329 (6139): 492. Bibcode:1987Natur.329..492M. doi:10.1038/329492a0. S2CID 45218186.
  61. ^ Harcourt, Richard D. (1987). "The electronic structure of the benzene molecule". Nature. 329 (6139): 491–492. Bibcode:1987Natur.329..491H. doi:10.1038/329491b0. S2CID 4268597.
  62. ^ "Unicode Character 'BENZENE RING' (U+232C)". fileformat.info. from the original on 2009-02-19. Retrieved 2009-01-16.
  63. ^ "Unicode Character 'BENZENE RING WITH CIRCLE' (U+23E3)". fileformat.info. from the original on 2009-07-03. Retrieved 2009-01-16.
  64. ^ "Heterocyclic Chemistry: Heterocyclic Compounds". Michigan State University, Department of Chemistry. from the original on 2016-04-06. Retrieved 2016-07-08.
  65. ^ Browne, Malcolm W. (August 16, 1988), "A pervasive molecule is captured in a photograph", The New York Times, from the original on August 12, 2021, retrieved August 13, 2021
  66. ^ "Market Study: Benzene (2nd edition), Ceresana, August 2014". ceresana.com. from the original on 2017-12-21. Retrieved 2015-02-10.
  67. ^ . ceresana.com. Archived from the original on 2017-04-29. Retrieved 2015-02-10.
  68. ^ Kolmetz, Gentry, Guidelines for BTX Revamps, AIChE 2007 Spring Conference
  69. ^ . U.S. Environmental Protection Agency. 2006-03-29. p. 15853. Archived from the original on 2008-12-05. Retrieved 2008-06-27.
  70. ^ Stranks, D. R.; M. L. Heffernan; K. C. Lee Dow; P. T. McTigue; G. R. A. Withers (1970). Chemistry: A structural view. Carlton, Victoria: Melbourne University Press. p. 347. ISBN 978-0-522-83988-3.
  71. ^ Welch, Vincent A.; Fallon, Kevin J.; Gelbke, Heinz-Peter (2005). "Ethylbenzene". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a10_035.pub2. ISBN 3527306730.
  72. ^ Kasper, Dennis L.et al. (2004) Harrison's Principles of Internal Medicine, 16th ed., McGraw-Hill Professional, p. 618, ISBN 0071402357.
  73. ^ Merck Manual, Home Edition 2011-09-29 at the Wayback Machine, "Overview of Leukemia".
  74. ^ Bard, D (2014). "Traffic-related air pollution and the onset of myocardial infarction: disclosing benzene as a trigger? A small-area case-crossover study". PLOS ONE. 9 (6): 6. Bibcode:2014PLoSO...9j0307B. doi:10.1371/journal.pone.0100307. PMC 4059738. PMID 24932584.
  75. ^ a b Smith, Martyn T. (2010). "Advances in understanding benzene health effects and susceptibility". Annu Rev Public Health. 31: 133–48. doi:10.1146/annurev.publhealth.012809.103646. PMC 4360999. PMID 20070208.
  76. ^ , Agency for Toxic Substances and Disease Registry, Department of Health and Human Services
  77. ^ Smith, Martyn T. (2010-01-01). "Advances in Understanding Benzene Health Effects and Susceptibility". Annual Review of Public Health. 31 (1): 133–148. doi:10.1146/annurev.publhealth.012809.103646. PMC 4360999. PMID 20070208.
  78. ^ WHO. International Agency for Research on Cancer, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Overall Evaluations of Carcinogenicity: An Updating of IARC Monographs 2008-03-06 at the Wayback Machine, Volumes 1 to 42, Supplement 7
  79. ^ Huff J (2007). "Benzene-induced cancers: abridged history and occupational health impact". Int J Occup Environ Health. 13 (2): 213–21. doi:10.1179/oeh.2007.13.2.213. PMC 3363002. PMID 17718179.
  80. ^ Rana SV; Verma Y (2005). "Biochemical toxicity of benzene". J Environ Biol. 26 (2): 157–68. PMID 16161967.
  81. ^ Agency for Toxic Substances and Disease Registry. (2007) Benzene: Patient information sheet. 2014-12-15 at the Wayback Machine
  82. ^ Yardley-Jones, A.; Anderson, D.; Parke, D. V. (1991). "The toxicity of benzene and its metabolism and molecular pathology in human risk assessment". British Journal of Industrial Medicine. 48 (7): 437–44. doi:10.1136/oem.48.7.437. PMC 1035396. PMID 1854646.
  83. ^ Occupational Safety and Health Standards, Toxic and Hazardous Substances, 1910.1028 2015-06-29 at the Wayback Machine. Osha.gov. Retrieved on 2011-11-23.
  84. ^ Public Health Statement for Benzene, Agency for Toxic Substances and Disease Registry. (August 2007). Benzene: Patient information sheet 2010-05-28 at the Wayback Machine. Atsdr.cdc.gov (2011-03-03). Retrieved on 2011-11-23.
  85. ^ . United States Environmental Protection Agency (EPA). Archived from the original on February 2, 2015. Retrieved April 17, 2014.
  86. ^ . Occupational Safety and Health Administration (OSHA). Archived from the original on June 29, 2015. Retrieved November 23, 2011.
  87. ^ . Agency for Toxic Substances and Disease Registry (ATSDR); Environmental Medicine & Environmental Health Education – CSEM. June 30, 2000. Archived from the original on June 10, 2010. Retrieved October 9, 2010.
  88. ^ a b (PDF). Cincinnati, Ohio: U.S. Department of Health and Human Services (DHHS), Public Health Service, Centers for Disease Control (CDC), National Institute for Occupational Safety and Health (NIOSH). October 2004. Archived from the original (PDF) on August 29, 2017. publication No. 2005-100.
  89. ^ . Centers for Disease Control (CDC). Archived from the original on April 1, 2019. Retrieved November 23, 2011.
  90. ^ "Public Health Statement for Benzene". Agency for Toxic Substances and Disease Registry. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health. August 2007. from the original on 2012-01-20. Retrieved 2011-11-23 – via Atsdr.cdc.gov.
  91. ^ Ashley, DL; Bonin, MA; Cardinali, FL; McCraw, JM; Wooten, JV (1994). "Blood concentrations of volatile organic compounds in a nonoccupationally exposed US population and in groups with suspected exposure" (PDF). Clinical Chemistry. 40 (7 Pt 2): 1401–4. doi:10.1093/clinchem/40.7.1401. PMID 8013127. (PDF) from the original on 2011-11-22. Retrieved 2010-08-25.
  92. ^ Fustinoni S, Buratti M, Campo L, Colombi A, Consonni D, Pesatori AC, Bonzini M, Farmer P, Garte S, Valerio F, Merlo DF, Bertazzi PA (2005). "Urinary t,t-muconic acid, S-phenylmercapturic acid and benzene as biomarkers of low benzene exposure". Chemico-Biological Interactions. 153–154: 253–6. doi:10.1016/j.cbi.2005.03.031. PMID 15935823.
  93. ^ ACGIH (2009). 2009 TLVs and BEIs. American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio.
  94. ^ Baselt, R. (2008) Disposition of Toxic Drugs and Chemicals in Man, 8th edition, Biomedical Publications, Foster City, CA, pp. 144–148, ISBN 0962652377.
  95. ^ Snyder, R; Hedli, C.C. (1996). "An overview of benzene metabolism". Environ Health Perspect. 104 (Suppl 6): 1165–1171. doi:10.1289/ehp.96104s61165. PMC 1469747. PMID 9118888.
  96. ^ Dougherty, D; Garte, S; Barchowsky, A; Zmuda, J; Taioli, E (2008). "NQO1, MPO, CYP2E1, GSTT1 and STM1 polymorphisms and biological effects of benzene exposure—a literature review". Toxicology Letters. 182 (1–3): 7–17. doi:10.1016/j.toxlet.2008.09.008. PMID 18848868.
  97. ^ Fracasso ME, Doria D, Bartolucci GB, Carrieri M, Lovreglio P, Ballini A, Soleo L, Tranfo G, Manno M (2010). "Low air levels of benzene: Correlation between biomarkers of exposure and genotoxic effects". Toxicol Lett. 192 (1): 22–8. doi:10.1016/j.toxlet.2009.04.028. PMID 19427373.
  98. ^ Eastmond, D.A.; Rupa, DS; Hasegawa, LS (2000). "Detection of hyperdiploidy and chromosome breakage in interphase human lymphocytes following exposure to the benzene metabolite hydroquinone using multicolor fluorescence in situ hybridization with DNA probes". Mutat Res. 322 (1): 9–20. doi:10.1016/0165-1218(94)90028-0. PMID 7517507.
  99. ^ Garte, S; Taioli, E; Popov, T; Bolognesi, C; Farmer, P; Merlo, F (2000). "Genetic susceptibility to benzene toxicity in humans". J Toxicol Environ Health A. 71 (22): 1482–1489. doi:10.1080/15287390802349974. PMID 18836923. S2CID 36885673.
  100. ^ ToxFAQs for Benzene, Agency for Toxic Substances and Disease Registry, Department of Health and Human Services 2008-03-09 at the Wayback Machine
  101. ^ ToxGuide for Benzene 2010-05-28 at the Wayback Machine, Agency for Toxic Substances and Disease Registry, Department of Health and Human Services
  102. ^ Public Health Statement. Benzene 2010-05-27 at the Wayback Machine, Division of Toxicology and Environmental Medicine, August 2007
  103. ^ Benzene, CASRN: 71-43-2 2011-10-22 at the Wayback Machine. Hazardous Substances Data Bank, U.S. National Library of Medicine. National Institutes of Health.
  104. ^ "FDA: Too Much Benzene In Some Drinks" 2007-02-18 at the Wayback Machine, CBS News, May 19, 2006. Retrieved July 11, 2006.
  105. ^ "100 tonnes of pollutants spilled into Chinese river". The Guardian. 25 November 2005. from the original on 10 March 2020. Retrieved 7 January 2020.
  106. ^ Isaacson, Kristofer P.; Proctor, Caitlin R.; Wang, Q. Erica; Edwards, Ethan Y.; Noh, Yoorae; Shah, Amisha D.; Whelton, Andrew J. (2021). "Drinking water contamination from the thermal degradation of plastics: Implications for wildfire and structure fire response". Environmental Science: Water Research & Technology. 7 (2): 274–284. doi:10.1039/D0EW00836B.
  107. ^ "Selections and lethal injections". Auschwitz-Birkenau State Museum. from the original on May 9, 2020. Retrieved May 15, 2020.
  108. ^ "A Former Nazi Labor Camp in Austria, Now Billed as a Tourist Site". Haaretz. May 3, 2019. from the original on May 11, 2019. Retrieved May 11, 2019.

External links

 
Wikimedia Commons has media related to:
Benzene (category)
 
Look up benzene in Wiktionary, the free dictionary.
 
Wikiquote has quotations related to Benzene.
 
Scholia has a chemical profile for Benzene.
  • Benzene at The Periodic Table of Videos (University of Nottingham)
  • International Chemical Safety Card 0015
  • USEPA Summary of Benzene Toxicity
  • NIOSH Pocket Guide to Chemical Hazards
  • Benzene from PubChem
  • Video Podcast of Sir John Cadogan giving a lecture on Benzene since Faraday, in 1991
  • Benzene in the ChemIDplus database
  • NLM Hazardous Substances Databank – Benzene

March 24, 2023
benzene, this, article, about, chemical, compound, other, uses, disambiguation, confused, with, petroleum, benzine, organic, chemical, compound, with, molecular, formula, c6h6, benzene, molecule, composed, carbon, atoms, joined, planar, ring, with, hydrogen, a. This article is about the chemical compound For other uses see Benzene disambiguation Not to be confused with Petroleum benzine Benzene is an organic chemical compound with the molecular formula C6H6 The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each Because it contains only carbon and hydrogen atoms benzene is classed as a hydrocarbon 15 Benzene Geometry Ball and stick modelSpace filling modelNamesIUPAC name Benzene 1 Other names Benzol historic German PhenanePhenylene hydrideCyclohexa 1 3 5 triene 1 3 5 Cyclohexatriene theoretical resonance isomers 6 Annulene not recommended 1 Phene historic IdentifiersCAS Number 71 43 2 Y3D model JSmol Interactive imageChEBI CHEBI 16716 YChEMBL ChEMBL277500 YChemSpider 236 YECHA InfoCard 100 000 685EC Number 200 753 7KEGG C01407 YPubChem CID 241RTECS number CY1400000UNII J64922108F YCompTox Dashboard EPA DTXSID3039242InChI InChI 1S C6H6 c1 2 4 6 5 3 1 h1 6H YKey UHOVQNZJYSORNB UHFFFAOYSA N YSMILES c1ccccc1PropertiesChemical formula C 6H 6Molar mass 78 114 g mol 1Appearance Colorless liquidOdor sweet aromaticDensity 0 8765 20 g cm3 2 Melting point 5 53 C 41 95 F 278 68 K Boiling point 80 1 C 176 2 F 353 2 K Solubility in water 1 53 g L 0 C 1 81 g L 9 C 1 79 g L 15 C 3 4 5 1 84 g L 30 C 2 26 g L 61 C 3 94 g L 100 C 21 7 g kg 200 C 6 5 MPa 17 8 g kg 200 C 40 MPa 6 Solubility Soluble in alcohol CHCl3 CCl4 diethyl ether acetone acetic acid 6 Solubility in ethanediol 5 83 g 100 g 20 C 6 61 g 100 g 40 C 7 61 g 100 g 60 C 6 Solubility in ethanol 20 C solution in ethanol 1 2 mL L 20 v v 7 Solubility in acetone 20 C solution in aceton 7 69 mL L 38 46 v v 49 4 mL L 62 5 v v 7 Solubility in diethylene glycol 52 g 100 g 20 C 6 log P 2 13Vapor pressure 12 7 kPa 25 C 24 4 kPa 40 C 181 kPa 100 C 8 Conjugate acid Benzenium 9 Conjugate base Benzenide 10 UV vis lmax 255 nmMagnetic susceptibility x 54 8 10 6 cm3 molRefractive index nD 1 5011 20 C 1 4948 30 C 6 Viscosity 0 7528 cP 10 C 0 6076 cP 25 C 0 4965 cP 40 C 0 3075 cP 80 C StructureMolecular shape Trigonal planarDipole moment 0 DThermochemistryHeat capacity C 134 8 J mol KStd molarentropy S 298 173 26 J mol K 8 Std enthalpy offormation DfH 298 48 7 kJ molStd enthalpy ofcombustion DcH 298 3267 6 kJ mol 8 HazardsOccupational safety and health OHS OSH Main hazards potential occupational carcinogen flammableGHS labelling Pictograms 11 Signal word DangerHazard statements H225 H302 H304 H305 H315 H319 H340 H350 H372 H410 11 Precautionary statements P201 P210 P301 P310 P305 P351 P338 P308 P313 P331 11 NFPA 704 fire diamond 230Flash point 11 63 C 11 07 F 261 52 K Autoignitiontemperature 497 78 C 928 00 F 770 93 K Explosive limits 1 2 7 8 Lethal dose or concentration LD LC LD50 median dose 80 8 mg kg rat oral 13 LCLo lowest published 44 000 ppm rabbit 30 min 44 923 ppm dog 52 308 ppm cat 20 000 ppm human 5 min 14 NIOSH US health exposure limits PEL Permissible TWA 1 ppm ST 5 ppm 12 REL Recommended Ca TWA 0 1 ppm ST 1 ppm 12 IDLH Immediate danger 500 ppm 12 Safety data sheet SDS HMDBRelated compoundsRelated compounds Toluene BorazineSupplementary data pageBenzene data page Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Y verify what is Y N Infobox references Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals Due to the cyclic continuous pi bonds between the carbon atoms benzene is classed as an aromatic hydrocarbon Benzene is a colorless and highly flammable liquid with a sweet smell and is partially responsible for the aroma of gasoline It is used primarily as a precursor to the manufacture of chemicals with more complex structure such as ethylbenzene and cumene of which billions of kilograms are produced annually Although benzene is a major industrial chemical it finds limited use in consumer items because of its toxicity Contents 1 History 1 1 Discovery 1 2 Ring formula 1 3 Nomenclature 1 4 Early applications 1 5 Occurrence 2 Structure 3 Benzene derivatives 4 Production 4 1 Catalytic reforming 4 2 Toluene hydrodealkylation 4 3 Toluene disproportionation 4 4 Steam cracking 4 5 Other methods 5 Uses 5 1 Component of gasoline 6 Reactions 6 1 Sulfonation chlorination nitration 6 2 Hydrogenation 6 3 Metal complexes 7 Health effects 8 Exposure to benzene 8 1 Benzene exposure limits 8 2 Toxicology 8 2 1 Biomarkers of exposure 8 2 2 Biotransformations 8 2 3 Molecular toxicology 8 2 4 Biological oxidation and carcinogenic activity 8 3 Routes of exposure 8 3 1 Inhalation 8 3 2 Exposure from soft drinks 8 3 3 Contamination of water supply 8 3 4 Genocide 9 See also 10 Explanatory notes 11 References 12 External linksHistory EditDiscovery Edit The word benzene derives from gum benzoin benzoin resin an aromatic resin known since ancient times in Southeast Asia and later to European pharmacists and perfumers in the 16th century via trade routes 16 An acidic material was derived from benzoin by sublimation and named flowers of benzoin or benzoic acid The hydrocarbon derived from benzoic acid thus acquired the name benzin benzol or benzene 17 Michael Faraday first isolated and identified benzene in 1825 from the oily residue derived from the production of illuminating gas giving it the name bicarburet of hydrogen 18 19 In 1833 Eilhard Mitscherlich produced it by distilling benzoic acid from gum benzoin and lime He gave the compound the name benzin 20 In 1836 the French chemist Auguste Laurent named the substance phene 21 this word has become the root of the English word phenol which is hydroxylated benzene and phenyl the radical formed by abstraction of a hydrogen atom free radical H from benzene Kekule s 1872 modification of his 1865 theory illustrating rapid alternation of double bonds note 1 In 1845 Charles Blachford Mansfield working under August Wilhelm von Hofmann isolated benzene from coal tar 22 Four years later Mansfield began the first industrial scale production of benzene based on the coal tar method 23 24 Gradually the sense developed among chemists that a number of substances were chemically related to benzene comprising a diverse chemical family In 1855 Hofmann used the word aromatic to designate this family relationship after a characteristic property of many of its members 25 In 1997 benzene was detected in deep space 26 Ring formula Edit Historic proposals of benzene structures By Adolf Karl Ludwig Claus 1867 27 By James Dewar 1869 28 By Albert Ladenburg 1869 29 By August Kekule 1865 1872 30 31 By Henry Edward Armstrong 1887 32 33 By Adolf von Baeyer 1888 34 By Friedrich Karl Johannes Thiele 1899 35 The empirical formula for benzene was long known but its highly polyunsaturated structure with just one hydrogen atom for each carbon atom was challenging to determine Archibald Scott Couper in 1858 and Johann Josef Loschmidt in 1861 36 suggested possible structures that contained multiple double bonds or multiple rings but too little evidence was then available to help chemists decide on any particular structure In 1865 the German chemist Friedrich August Kekule published a paper in French for he was then teaching in Francophone Belgium suggesting that the structure contained a ring of six carbon atoms with alternating single and double bonds The next year he published a much longer paper in German on the same subject 30 37 Kekule used evidence that had accumulated in the intervening years namely that there always appeared to be only one isomer of any monoderivative of benzene and that there always appeared to be exactly three isomers of every disubstituted derivative now understood to correspond to the ortho meta and para patterns of arene substitution to argue in support of his proposed structure 38 Kekule s symmetrical ring could explain these curious facts as well as benzene s 1 1 carbon hydrogen ratio The new understanding of benzene and hence of all aromatic compounds proved to be so important for both pure and applied chemistry that in 1890 the German Chemical Society organized an elaborate appreciation in Kekule s honor celebrating the twenty fifth anniversary of his first benzene paper Here Kekule spoke of the creation of the theory He said that he had discovered the ring shape of the benzene molecule after having a reverie or day dream of a snake biting its own tail this is a common symbol in many ancient cultures known as the Ouroboros or endless knot 39 This vision he said came to him after years of studying the nature of carbon carbon bonds This was seven years after he had solved the problem of how carbon atoms could bond to up to four other atoms at the same time Curiously a similar humorous depiction of benzene had appeared in 1886 in a pamphlet entitled Berichte der Durstigen Chemischen Gesellschaft Journal of the Thirsty Chemical Society a parody of the Berichte der Deutschen Chemischen Gesellschaft only the parody had monkeys seizing each other in a circle rather than snakes as in Kekule s anecdote 40 Some historians have suggested that the parody was a lampoon of the snake anecdote possibly already well known through oral transmission even if it had not yet appeared in print 17 Kekule s 1890 speech 41 in which this anecdote appeared has been translated into English 42 If the anecdote is the memory of a real event circumstances mentioned in the story suggest that it must have happened early in 1862 43 In 1929 the cyclic nature of benzene was finally confirmed by the crystallographer Kathleen Lonsdale using X ray diffraction methods 44 45 Using large crystals of hexamethylbenzene a benzene derivative with the same core of six carbon atoms Lonsdale obtained diffraction patterns Through calculating more than thirty parameters Lonsdale demonstrated that the benzene ring could not be anything but a flat hexagon and provided accurate distances for all carbon carbon bonds in the molecule 46 Nomenclature Edit The German chemist Wilhelm Korner suggested the prefixes ortho meta para to distinguish di substituted benzene derivatives in 1867 however he did not use the prefixes to distinguish the relative positions of the substituents on a benzene ring 47 48 It was the German chemist Carl Grabe who in 1869 first used the prefixes ortho meta para to denote specific relative locations of the substituents on a di substituted aromatic ring viz naphthalene 49 In 1870 the German chemist Viktor Meyer first applied Grabe s nomenclature to benzene 50 Early applications Edit In the 19th and early 20th centuries benzene was used as an after shave lotion because of its pleasant smell citation needed Prior to the 1920s benzene was frequently used as an industrial solvent especially for degreasing metal As its toxicity became obvious benzene was supplanted by other solvents especially toluene methylbenzene which has similar physical properties but is not as carcinogenic In 1903 Ludwig Roselius popularized the use of benzene to decaffeinate coffee This discovery led to the production of Sanka This process was later discontinued Benzene was historically used as a significant component in many consumer products such as liquid wrench several paint strippers rubber cements spot removers and other products Manufacture of some of these benzene containing formulations ceased in about 1950 although Liquid Wrench continued to contain significant amounts of benzene until the late 1970s 51 Occurrence Edit Trace amounts of benzene are found in petroleum and coal It is a byproduct of the incomplete combustion of many materials For commercial use until World War II much of benzene was obtained as a by product of coke production or coke oven light oil for the steel industry However in the 1950s increased demand for benzene especially from the growing polymers industry necessitated the production of benzene from petroleum Today most benzene comes from the petrochemical industry with only a small fraction being produced from coal 52 Benzene molecules have been detected on Mars 53 54 55 Structure EditMain article Aromaticity The various representations of benzene X ray diffraction shows that all six carbon carbon bonds in benzene are of the same length at 140 picometres pm 56 The C C bond lengths are greater than a double bond 135 pm but shorter than a single bond 147 pm This intermediate distance is caused by electron delocalization the electrons for C C bonding are distributed equally between each of the six carbon atoms Benzene has 6 hydrogen atoms fewer than the corresponding parent alkane hexane which has 14 Benzene and cyclohexane have a similar structure only the ring of delocalized electrons and the loss of one hydrogen per carbon distinguishes it from cyclohexane The molecule is planar 57 The molecular orbital description involves the formation of three delocalized p orbitals spanning all six carbon atoms while the valence bond description involves a superposition of resonance structures 58 59 60 61 It is likely that this stability contributes to the peculiar molecular and chemical properties known as aromaticity To accurately reflect the nature of the bonding benzene is often depicted with a circle inside a hexagonal arrangement of carbon atoms Derivatives of benzene occur sufficiently often as a component of organic molecules so much so that the Unicode Consortium has allocated a symbol in the Miscellaneous Technical block with the code U 232C to represent it with three double bonds 62 and U 23E3 for a delocalized version 63 Benzene derivatives EditMain articles Aromatic hydrocarbons and Alkylbenzenes Many important chemical compounds are derived from benzene by replacing one or more of its hydrogen atoms with another functional group Examples of simple benzene derivatives are phenol toluene and aniline abbreviated PhOH PhMe and PhNH2 respectively Linking benzene rings gives biphenyl C6H5 C6H5 Further loss of hydrogen gives fused aromatic hydrocarbons such as naphthalene anthracene phenanthrene and pyrene The limit of the fusion process is the hydrogen free allotrope of carbon graphite In heterocycles carbon atoms in the benzene ring are replaced with other elements The most important variations contain nitrogen Replacing one CH with N gives the compound pyridine C5H5N Although benzene and pyridine are structurally related benzene cannot be converted into pyridine Replacement of a second CH bond with N gives depending on the location of the second N pyridazine pyrimidine or pyrazine 64 Production EditFour chemical processes contribute to industrial benzene production catalytic reforming toluene hydrodealkylation toluene disproportionation and steam cracking etc According to the ATSDR Toxicological Profile for benzene between 1978 and 1981 catalytic reformates accounted for approximately 44 50 of the total U S benzene production 52 Catalytic reforming Edit In catalytic reforming a mixture of hydrocarbons with boiling points between 60 and 200 C is blended with hydrogen gas and then exposed to a bifunctional platinum chloride or rhenium chloride catalyst at 500 525 C and pressures ranging from 8 50 atm Under these conditions aliphatic hydrocarbons form rings and lose hydrogen to become aromatic hydrocarbons The aromatic products of the reaction are then separated from the reaction mixture or reformate by extraction with any one of a number of solvents including diethylene glycol or sulfolane and benzene is then separated from the other aromatics by distillation The extraction step of aromatics from the reformate is designed to produce aromatics with lowest non aromatic components Recovery of the aromatics commonly referred to as BTX benzene toluene and xylene isomers involves such extraction and distillation steps In similar fashion to this catalytic reforming UOP and BP commercialized a method from LPG mainly propane and butane to aromatics Toluene hydrodealkylation Edit Toluene hydrodealkylation converts toluene to benzene In this hydrogen intensive process toluene is mixed with hydrogen then passed over a chromium molybdenum or platinum oxide catalyst at 500 650 C and 20 60 atm pressure Sometimes higher temperatures are used instead of a catalyst at the similar reaction condition Under these conditions toluene undergoes dealkylation to benzene and methane C 6 H 5 CH 3 H 2 C 6 H 6 CH 4 displaystyle ce C6H5CH3 H2 gt C6H6 CH4 This irreversible reaction is accompanied by an equilibrium side reaction that produces biphenyl aka diphenyl at higher temperature 2 C6 H6 H2 C6 H5 C6 H5If the raw material stream contains much non aromatic components paraffins or naphthenes those are likely decomposed to lower hydrocarbons such as methane which increases the consumption of hydrogen A typical reaction yield exceeds 95 Sometimes xylenes and heavier aromatics are used in place of toluene with similar efficiency This is often called on purpose methodology to produce benzene compared to conventional BTX benzene toluene xylene extraction processes Toluene disproportionation Edit Toluene disproportionation TDP is the conversion of toluene to benzene and xylene Given that demand for para xylene p xylene substantially exceeds demand for other xylene isomers a refinement of the TDP process called Selective TDP STDP may be used In this process the xylene stream exiting the TDP unit is approximately 90 p xylene In some systems even the benzene to xylenes ratio is modified to favor xylenes Steam cracking Edit Steam cracking is the process for producing ethylene and other alkenes from aliphatic hydrocarbons Depending on the feedstock used to produce the olefins steam cracking can produce a benzene rich liquid by product called pyrolysis gasoline Pyrolysis gasoline can be blended with other hydrocarbons as a gasoline additive or routed through an extraction process to recover BTX aromatics benzene toluene and xylenes Other methods Edit Although of no commercial significance many other routes to benzene exist Phenol and halobenzenes can be reduced with metals Benzoic acid and its salts undergo decarboxylation to benzene The reaction of the diazonium compound derived from aniline with hypophosphorus acid gives benzene Alkyne trimerisation of acetylene gives benzene Complete decarboxylation of mellitic acid gives benzene Uses EditBenzene is used mainly as an intermediate to make other chemicals above all ethylbenzene and other alkylbenzenes cumene cyclohexane and nitrobenzene In 1988 it was reported that two thirds of all chemicals on the American Chemical Society s lists contained at least one benzene ring 65 More than half of the entire benzene production is processed into ethylbenzene a precursor to styrene which is used to make polymers and plastics like polystyrene Some 20 of the benzene production is used to manufacture cumene which is needed to produce phenol and acetone for resins and adhesives Cyclohexane consumes around 10 of the world s benzene production it is primarily used in the manufacture of nylon fibers which are processed into textiles and engineering plastics Smaller amounts of benzene are used to make some types of rubbers lubricants dyes detergents drugs explosives and pesticides In 2013 the biggest consumer country of benzene was China followed by the USA Benzene production is currently expanding in the Middle East and in Africa whereas production capacities in Western Europe and North America are stagnating 66 Toluene is now often used as a substitute for benzene for instance as a fuel additive The solvent properties of the two are similar but toluene is less toxic and has a wider liquid range Toluene is also processed into benzene 67 Major commodity chemicals and polymers derived from benzene Clicking on the image loads the appropriate article Component of gasoline Edit As a gasoline petrol additive benzene increases the octane rating and reduces knocking As a consequence gasoline often contained several percent benzene before the 1950s when tetraethyl lead replaced it as the most widely used antiknock additive With the global phaseout of leaded gasoline benzene has made a comeback as a gasoline additive in some nations In the United States concern over its negative health effects and the possibility of benzene entering the groundwater has led to stringent regulation of gasoline s benzene content with limits typically around 1 68 European petrol specifications now contain the same 1 limit on benzene content The United States Environmental Protection Agency introduced new regulations in 2011 that lowered the benzene content in gasoline to 0 62 69 In many European languages the word for petroleum or gasoline is an exact cognate of benzene citation needed Reactions EditThe most common reactions of benzene involve substitution of a proton by other groups 70 Electrophilic aromatic substitution is a general method of derivatizing benzene Benzene is sufficiently nucleophilic that it undergoes substitution by acylium ions and alkyl carbocations to give substituted derivatives Electrophilic aromatic substitution of benzeneThe most widely practiced example of this reaction is the ethylation of benzene dd Approximately 24 700 000 tons were produced in 1999 71 Highly instructive but of far less industrial significance is the Friedel Crafts alkylation of benzene and many other aromatic rings using an alkyl halide in the presence of a strong Lewis acid catalyst Similarly the Friedel Crafts acylation is a related example of electrophilic aromatic substitution The reaction involves the acylation of benzene or many other aromatic rings with an acyl chloride using a strong Lewis acid catalyst such as aluminium chloride or Iron III chloride Friedel Crafts acylation of benzene by acetyl chloride Sulfonation chlorination nitration Edit Using electrophilic aromatic substitution many functional groups are introduced onto the benzene framework Sulfonation of benzene involves the use of oleum a mixture of sulfuric acid with sulfur trioxide Sulfonated benzene derivatives are useful detergents In nitration benzene reacts with nitronium ions NO2 which is a strong electrophile produced by combining sulfuric and nitric acids Nitrobenzene is the precursor to aniline Chlorination is achieved with chlorine to give chlorobenzene in the presence of a Lewis acid catalyst such as aluminium tri chloride Hydrogenation Edit Via hydrogenation benzene and its derivatives convert to cyclohexane and derivatives This reaction is achieved by the use of high pressures of hydrogen in the presence of heterogeneous catalysts such as finely divided nickel Whereas alkenes can be hydrogenated near room temperatures benzene and related compounds are more reluctant substrates requiring temperatures gt 100 C This reaction is practiced on a large scale industrially In the absence of the catalyst benzene is impervious to hydrogen Hydrogenation cannot be stopped to give cyclohexene or cyclohexadienes as these are superior substrates Birch reduction a non catalytic process however selectively hydrogenates benzene to the diene Metal complexes Edit Benzene is an excellent ligand in the organometallic chemistry of low valent metals Important examples include the sandwich and half sandwich complexes respectively Cr C6H6 2 and RuCl2 C6H6 2 Health effects Edit A bottle of benzene The warnings show benzene is a toxic and flammable liquid Benzene is classified as a carcinogen which increases the risk of cancer and other illnesses and is also a notorious cause of bone marrow failure Substantial quantities of epidemiologic clinical and laboratory data link benzene to aplastic anemia acute leukemia bone marrow abnormalities and cardiovascular disease 72 73 74 The specific hematologic malignancies that benzene is associated with include acute myeloid leukemia AML aplastic anemia myelodysplastic syndrome MDS acute lymphoblastic leukemia ALL and chronic myeloid leukemia CML 75 The American Petroleum Institute API stated in 1948 that it is generally considered that the only absolutely safe concentration for benzene is zero 76 There is no safe exposure level even tiny amounts can cause harm 77 The US Department of Health and Human Services DHHS classifies benzene as a human carcinogen Long term exposure to excessive levels of benzene in the air causes leukemia a potentially fatal cancer of the blood forming organs In particular acute myeloid leukemia or acute nonlymphocytic leukemia AML amp ANLL is caused by benzene 78 IARC rated benzene as known to be carcinogenic to humans Group 1 As benzene is ubiquitous in gasoline and hydrocarbon fuels that are in use everywhere human exposure to benzene is a global health problem Benzene targets the liver kidney lung heart and brain and can cause DNA strand breaks and chromosomal damage Benzene causes cancer in animals including humans Benzene has been shown to cause cancer in both sexes of multiple species of laboratory animals exposed via various routes 79 80 Exposure to benzene EditAccording to the Agency for Toxic Substances and Disease Registry ATSDR 2007 benzene is both a synthetically made and naturally occurring chemical from processes that include volcanic eruptions wild fires synthesis of chemicals such as phenol production of synthetic fibers and fabrication of rubbers lubricants pesticides medications and dyes The major sources of benzene exposure are tobacco smoke automobile service stations exhaust from motor vehicles and industrial emissions however ingestion and dermal absorption of benzene can also occur through contact with contaminated water Benzene is hepatically metabolized and excreted in the urine Measurement of air and water levels of benzene is accomplished through collection via activated charcoal tubes which are then analyzed with a gas chromatograph The measurement of benzene in humans can be accomplished via urine blood and breath tests however all of these have their limitations because benzene is rapidly metabolized in the human body 81 Exposure to benzene may lead progressively to aplastic anemia leukaemia and multiple myeloma 82 OSHA regulates levels of benzene in the workplace 83 The maximum allowable amount of benzene in workroom air during an 8 hour workday 40 hour workweek is 1 ppm As benzene can cause cancer NIOSH recommends that all workers wear special breathing equipment when they are likely to be exposed to benzene at levels exceeding the recommended 8 hour exposure limit of 0 1 ppm 84 Benzene exposure limits Edit The United States Environmental Protection Agency has set a maximum contaminant level for benzene in drinking water at 0 0005 mg L 5 ppb as promulgated via the U S National Primary Drinking Water Regulations 85 This regulation is based on preventing benzene leukemogenesis The maximum contaminant level goal MCLG a nonenforceable health goal that would allow an adequate margin of safety for the prevention of adverse effects is zero benzene concentration in drinking water The EPA requires that spills or accidental releases into the environment of 10 pounds 4 5 kg or more of benzene be reported The U S Occupational Safety and Health Administration OSHA has set a permissible exposure limit of 1 part of benzene per million parts of air 1 ppm in the workplace during an 8 hour workday 40 hour workweek The short term exposure limit for airborne benzene is 5 ppm for 15 minutes 86 These legal limits were based on studies demonstrating compelling evidence of health risk to workers exposed to benzene The risk from exposure to 1 ppm for a working lifetime has been estimated as 5 excess leukemia deaths per 1 000 employees exposed This estimate assumes no threshold for benzene s carcinogenic effects OSHA has also established an action level of 0 5 ppm to encourage even lower exposures in the workplace 87 The U S National Institute for Occupational Safety and Health NIOSH revised the Immediately Dangerous to Life and Health IDLH concentration for benzene to 500 ppm The current NIOSH definition for an IDLH condition as given in the NIOSH Respirator Selection Logic is one that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment 88 The purpose of establishing an IDLH value is 1 to ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment and 2 is considered a maximum level above which only a highly reliable breathing apparatus providing maximum worker protection is permitted 88 89 In September 1995 NIOSH issued a new policy for developing recommended exposure limits RELs for substances including carcinogens As benzene can cause cancer NIOSH recommends that all workers wear special breathing equipment when they are likely to be exposed to benzene at levels exceeding the REL 10 hour of 0 1 ppm 90 The NIOSH short term exposure limit STEL 15 min is 1 ppm American Conference of Governmental Industrial Hygienists ACGIH adopted Threshold Limit Values TLVs for benzene at 0 5 ppm TWA and 2 5 ppm STEL citation needed Toxicology Edit Biomarkers of exposure Edit Several tests can determine exposure to benzene Benzene itself can be measured in breath blood or urine but such testing is usually limited to the first 24 hours post exposure due to the relatively rapid removal of the chemical by exhalation or biotransformation Most people in developed countries have measureable baseline levels of benzene and other aromatic petroleum hydrocarbons in their blood In the body benzene is enzymatically converted to a series of oxidation products including muconic acid phenylmercapturic acid phenol catechol hydroquinone and 1 2 4 trihydroxybenzene Most of these metabolites have some value as biomarkers of human exposure since they accumulate in the urine in proportion to the extent and duration of exposure and they may still be present for some days after exposure has ceased The current ACGIH biological exposure limits for occupational exposure are 500 mg g creatinine for muconic acid and 25 mg g creatinine for phenylmercapturic acid in an end of shift urine specimen 91 92 93 94 Biotransformations Edit Even if it is not a common substrate for metabolism benzene can be oxidized by both bacteria and eukaryotes In bacteria dioxygenase enzyme can add an oxygen to the ring and the unstable product is immediately reduced by NADH to a cyclic diol with two double bonds breaking the aromaticity Next the diol is newly reduced by NADH to catechol The catechol is then metabolized to acetyl CoA and succinyl CoA used by organisms mainly in the citric acid cycle for energy production The pathway for the metabolism of benzene is complex and begins in the liver Several enzymes are involved These include cytochrome P450 2E1 CYP2E1 quinine oxidoreductase NQ01 or DT diaphorase or NAD P H dehydrogenase quinone 1 GSH and myeloperoxidase MPO CYP2E1 is involved at multiple steps converting benzene to oxepin benzene oxide phenol to hydroquinone and hydroquinone to both benzenetriol and catechol Hydroquinone benzenetriol and catechol are converted to polyphenols In the bone marrow MPO converts these polyphenols to benzoquinones These intermediates and metabolites induce genotoxicity by multiple mechanisms including inhibition of topoisomerase II which maintains chromosome structure disruption of microtubules which maintains cellular structure and organization generation of oxygen free radicals unstable species that may lead to point mutations increasing oxidative stress inducing DNA strand breaks and altering DNA methylation which can affect gene expression NQ01 and GSH shift metabolism away from toxicity NQ01 metabolizes benzoquinone toward polyphenols counteracting the effect of MPO GSH is involved with the formation of phenylmercapturic acid 75 95 Genetic polymorphisms in these enzymes may induce loss of function or gain of function For example mutations in CYP2E1 increase activity and result in increased generation of toxic metabolites NQ01 mutations result in loss of function and may result in decreased detoxification Myeloperoxidase mutations result in loss of function and may result in decreased generation of toxic metabolites GSH mutations or deletions result in loss of function and result in decreased detoxification These genes may be targets for genetic screening for susceptibility to benzene toxicity 96 Molecular toxicology Edit The paradigm of toxicological assessment of benzene is shifting towards the domain of molecular toxicology as it allows understanding of fundamental biological mechanisms in a better way Glutathione seems to play an important role by protecting against benzene induced DNA breaks and it is being identified as a new biomarker for exposure and effect 97 Benzene causes chromosomal aberrations in the peripheral blood leukocytes and bone marrow explaining the higher incidence of leukemia and multiple myeloma caused by chronic exposure These aberrations can be monitored using fluorescent in situ hybridization FISH with DNA probes to assess the effects of benzene along with the hematological tests as markers of hematotoxicity 98 Benzene metabolism involves enzymes coded for by polymorphic genes Studies have shown that genotype at these loci may influence susceptibility to the toxic effects of benzene exposure Individuals carrying variant of NAD P H quinone oxidoreductase 1 NQO1 microsomal epoxide hydrolase EPHX and deletion of the glutathione S transferase T1 GSTT1 showed a greater frequency of DNA single stranded breaks 99 Biological oxidation and carcinogenic activity Edit One way of understanding the carcinogenic effects of benzene is by examining the products of biological oxidation Pure benzene for example oxidizes in the body to produce an epoxide benzene oxide which is not excreted readily and can interact with DNA to produce harmful mutations Routes of exposure Edit Inhalation Edit Outdoor air may contain low levels of benzene from automobile service stations wood smoke tobacco smoke the transfer of gasoline exhaust from motor vehicles and industrial emissions 100 About 50 of the entire nationwide United States exposure to benzene results from smoking tobacco or from exposure to tobacco smoke 101 After smoking 32 cigarettes per day the smoker would take in about 1 8 milligrams mg of benzene This amount is about 10 times the average daily intake of benzene by nonsmokers 102 Inhaled benzene is primarily expelled unchanged through exhalation In a human study 16 4 to 41 6 of retained benzene was eliminated through the lungs within five to seven hours after a two to three hour exposure to 47 to 110 ppm and only 0 07 to 0 2 of the remaining benzene was excreted unchanged in the urine After exposure to 63 to 405 mg m3 of benzene for 1 to 5 hours 51 to 87 was excreted in the urine as phenol over a period of 23 to 50 hours In another human study 30 of absorbed dermally applied benzene which is primarily metabolized in the liver was excreted as phenol in the urine 103 Exposure from soft drinks Edit Main article Benzene in soft drinks Under specific conditions and in the presence of other chemicals benzoic acid a preservative and ascorbic acid Vitamin C may interact to produce benzene In March 2006 the official Food Standards Agency in United Kingdom conducted a survey of 150 brands of soft drinks It found that four contained benzene levels above World Health Organization limits The affected batches were removed from sale Similar problems were reported by the FDA in the United States 104 Contamination of water supply Edit In 2005 the water supply to the city of Harbin in China with a population of almost nine million people was cut off because of a major benzene exposure 105 Benzene leaked into the Songhua River which supplies drinking water to the city after an explosion at a China National Petroleum Corporation CNPC factory in the city of Jilin on 13 November 2005 When plastic water pipes are subject to high heat the water may be contaminated with benzene 106 Genocide Edit The Nazis used benzene administered via injection as one of their many methods for killing 107 108 See also Edit Environment portal Medicine portalBTEX Industrial Union Department v American Petroleum Institute Six membered aromatic rings with one carbon replaced by another element borabenzene silabenzene germabenzene stannabenzene pyridine phosphorine arsabenzene bismabenzene pyrylium thiopyrylium selenopyrylium telluropyryliumExplanatory notes Edit Critics pointed out a problem with Kekule s original 1865 structure for benzene Whenever benzene underwent substitution at the ortho position two distinguishable isomers should have resulted depending on whether a double bond or a single bond existed between the carbon atoms to which the substituents were attached however no such isomers were observed In 1872 Kekule suggested that benzene had two complementary structures and that these forms rapidly interconverted so that if there were a double bond between any pair of carbon atoms at one instant that double bond would become a single bond at the next instant and vice versa To provide a mechanism for the conversion process Kekule proposed that the valency of an atom is determined by the frequency with which it collided with its neighbors in a molecule As the carbon atoms in the benzene ring collided with each other each carbon atom would collide twice with one neighbor during a given interval and then twice with its other neighbor during the next interval Thus a double bond would exist with one neighbor during the first interval and with the other neighbor during the next interval Therefore between the carbon atoms of benzene there were no fixed i e constant and distinct single or double bonds instead the bonds between the carbon atoms were identical See pages 86 89 Archived 2020 03 20 at the Wayback Machine of Auguste Kekule 1872 Ueber einige Condensationsprodukte des Aldehyds On some condensation products of aldehydes Liebig s Annalen der Chemie und Pharmacie 162 1 77 124 309 320 From p 89 Das einfachste Mittel aller Stosse eines Kohlenstoffatoms ergiebt sich aus der Summe der Stosse der beiden ersten Zeiteinheiten die sich dann periodisch wiederholen man sieht daher dass jedes Kohlenstoffatom mit den beiden anderen dass diese Verschiedenheit nur eine scheinbare aber keine wirkliche ist The simplest average of all the collisions of a carbon atom in benzene comes from the sum of the collisions during the first two units of time which then periodically repeat thus one sees that each carbon atom collides equally often with the two others against which it bumps and thus stands in exactly the same relation with its two neighbors The usual structural formula for benzene expresses of course only the collisions that occur during one unit of time thus during one phase and so one is led to the view that doubly substituted derivatives of benzene must be different at positions 1 2 and 1 6 of the benzene ring If the idea that was just presented or a similar one can be regarded as correct then it follows therefrom that this difference between the bonds at positions 1 2 and 1 6 is only an apparent one not a real one References Edit a b Favre Henri A Powell Warren H 2014 Nomenclature of Organic Chemistry IUPAC Recommendations and Preferred Names 2013 Blue Book Cambridge The Royal Society of Chemistry pp 10 22 204 494 577 doi 10 1039 9781849733069 ISBN 978 0 85404 182 4 Lide D R ed 2005 CRC Handbook of Chemistry and Physics 86th ed Boca Raton FL CRC Press ISBN 0 8493 0486 5 Arnold D Plank C Erickson E Pike F 1958 Solubility of Benzene in Water Industrial amp Engineering Chemistry Chemical amp Engineering Data Series 3 2 253 256 doi 10 1021 i460004a016 Breslow R Guo T 1990 Surface tension measurements show that chaotropic salting in denaturants are not just water structure breakers Proceedings of the National Academy of Sciences of the United States of America 87 1 167 9 Bibcode 1990PNAS 87 167B doi 10 1073 pnas 87 1 167 PMC 53221 PMID 2153285 Coker A Kayode Ludwig Ernest E 2007 Ludwig s Applied Process Design for Chemical And Petrochemical Plants Vol 1 Elsevier p 114 ISBN 978 0 7506 7766 0 Archived from the original on 2016 03 12 Retrieved 2012 05 31 a b c d e Benzol Archived from the original on 2014 05 29 Retrieved 2014 05 29 a b Atherton Seidell William F Linke 1952 Solubilities of Inorganic and Organic Compounds A Compilation of Solubility Data from the Periodical Literature Supplement Van Nostrand Archived from the original on 2020 03 11 Retrieved 2015 06 27 a b c Benzene in Linstrom Peter J Mallard William G eds NIST Chemistry WebBook NIST Standard Reference Database Number 69 National Institute of Standards and Technology Gaithersburg MD retrieved 2014 05 29 Benzenium CID 12533897 PubChem February 8 2007 Retrieved September 18 2022 Benzenide CID 5150480 PubChem June 24 2005 Retrieved September 18 2022 a b c Sigma Aldrich Co Benzene Archived 2016 12 01 at the Wayback Machine Retrieved on 2014 05 29 a b c NIOSH Pocket Guide to Chemical Hazards 0049 National Institute for Occupational Safety and Health NIOSH Benzene toxicity Benzene Immediately Dangerous to Life or Health Concentrations IDLH National Institute for Occupational Safety and Health NIOSH Benzene an overview ScienceDirect Topics www sciencedirect com Archived from the original on 2021 02 08 Retrieved 2020 11 25 The word benzoin is derived from the Arabic expression luban jawi or frankincense of Java Morris Edwin T 1984 Fragrance The Story of Perfume from Cleopatra to Chanel Charles Scribner s Sons p 101 ISBN 978 0684181950 a b Rocke A J 1985 Hypothesis and Experiment in the Early Development of Kekule s Benzene Theory Annals of Science 42 4 355 81 doi 10 1080 00033798500200411 Faraday M 1825 On new compounds of carbon and hydrogen and on certain other products obtained during the decomposition of oil by heat Philosophical Transactions of the Royal Society 115 440 466 doi 10 1098 rstl 1825 0022 JSTOR 107752 Archived from the original on 2020 11 21 Retrieved 2012 01 15 On pages 443 450 Faraday discusses bicarburet of hydrogen benzene On pages 449 450 he shows that benzene s empirical formula is C6H6 although he doesn t realize it because he like most chemists at that time used the wrong atomic mass for carbon 6 instead of 12 Kaiser R 1968 Bicarburet of Hydrogen Reappraisal of the Discovery of Benzene in 1825 with the Analytical Methods of 1968 Angewandte Chemie International Edition in English 7 5 345 350 doi 10 1002 anie 196803451 Mitscherlich E 1834 Uber das Benzol und die Sauren der Oel und Talgarten On benzol and oily and fatty types of acids Annalen der Pharmacie 9 1 39 48 doi 10 1002 jlac 18340090103 Archived from the original on 2015 11 23 Retrieved 2015 06 27 In a footnote on page 43 Liebig the journal s editor suggested changing Mitscherlich s original name for benzene namely benzin to benzol because the suffix in suggested that it was an alkaloid e g Chinin quinine which benzene isn t whereas the suffix ol suggested that it was oily which benzene is Thus on page 44 Mitscherlich states Da diese Flussigkeit aus der Benzoesaure gewonnen wird und wahrscheinlich mit den Benzoylverbindungen im Zusammenhang steht so gibt man ihr am besten den Namen Benzol da der Name Benzoin schon fur die mit dem Bittermandelol isomerische Verbindung von Liebig und Wohler gewahlt worden ist Since this liquid benzene is obtained from benzoic acid and probably is related to benzoyl compounds the best name for it is benzol since the name benzoin has already been chosen by Liebig and Wohler for the compound that s isomeric with the oil of bitter almonds benzaldehyde Laurent Auguste 1836 Sur la chlorophenise et les acides chlorophenisique et chlorophenesique Annales de Chemie et de Physique vol 63 pp 27 45 see p 44 Archived 2015 03 20 at the Wayback Machine Je donne le nom de phene au radical fondamental des acides precedens fainw j eclaire puisque la benzine se trouve dans le gaz de l eclairage I give the name of phene fainw I illuminate to the fundamental radical of the preceding acids because benzene is found in illuminating gas Hofmann A W 1845 Ueber eine sichere Reaction auf Benzol On a reliable test for benzene Annalen der Chemie und Pharmacie in German 55 2 200 205 especially 204 205 doi 10 1002 jlac 18450550205 Archived from the original on 2015 11 22 Mansfield Charles Blachford 1849 Untersuchung des Steinkohlentheers Annalen der Chemie und Pharmacie 69 2 162 180 doi 10 1002 jlac 18490690203 Archived from the original on 2015 10 27 Retrieved 2015 06 27 Charles Mansfield filed for November 11 1847 and received May 1848 a patent no 11 960 for the fractional distillation of coal tar Hoffman Augustus W 1856 On insolinic acid Proceedings of the Royal Society 8 1 3 doi 10 1098 rspl 1856 0002 The existence and mode of formation of insolinic acid prove that to the series of monobasic aromatic acids Cn2Hn2 8O4 the lowest known term of which is benzoic acid Note The empirical formulas of organic compounds that appear in Hofmann s article p 3 are based upon an atomic mass of carbon of 6 instead of 12 and an atomic mass of oxygen of 8 instead of 16 Cernicharo Jose et al 1997 Infrared Space Observatory s Discovery of C4H2 C6H2 and Benzene in CRL 618 Astrophysical Journal Letters 546 2 L123 L126 Bibcode 2001ApJ 546L 123C doi 10 1086 318871 Claus Adolph K L 1867 Theoretische Betrachtungen und deren Anwendungen zur Systematik der organischen Chemie Theoretical considerations and their applications to the classification scheme of organic chemistry Berichte uber die Verhandlungen der Naturforschenden Gesellschaft zu Freiburg im Breisgau Reports of the Proceedings of the Scientific Society of Freiburg in Breisgau 4 116 381 In the section Aromatischen Verbindungen aromatic compounds pp 315 347 Claus presents Kekule s hypothetical structure for benzene p 317 presents objections to it presents an alternative geometry p 320 and concludes that his alternative is correct p 326 See also figures on p 354 or p 379 Dewar James 1869 On the oxidation of phenyl alcohol and a mechanical arrangement adapted to illustrate structure in the non saturated hydrocarbons Proceedings of the Royal Society of Edinburgh 6 82 86 doi 10 1017 S0370164600045387 Archived from the original on 2015 11 24 Retrieved 2015 06 27 Ladenburg Albert 1869 Bemerkungen zur aromatischen Theorie Observations on the aromatic theory Berichte der Deutschen Chemischen Gesellschaft 2 140 142 doi 10 1002 cber 18690020171 Archived from the original on 2015 11 22 Retrieved 2015 06 27 a b Kekule F A 1865 Sur la constitution des substances aromatiques Bulletin de la Societe Chimique de Paris 3 98 110 Archived from the original on 2015 11 14 Retrieved 2015 06 27 On p 100 Kekule suggests that the carbon atoms of benzene could form a chaine fermee a closed chain a loop Aug Kekule 1872 Ueber einige Condensationsproducte des Aldehyds PDF Annalen der Chemie und Pharmacie in German vol 162 no 1 pp 77 124 doi 10 1002 jlac 18721620110 Armstrong Henry E 1887 An explanation of the laws which govern substitution in the case of benzenoid compounds Journal of the Chemical Society 51 258 268 264 doi 10 1039 ct8875100258 Archived from the original on 2015 10 22 Retrieved 2015 06 27 In his 1890 paper Armstrong represented benzene nuclei within polycyclic benzenoids by placing inside the benzene nuclei a letter C an abbreviation of the word centric Centric affinities i e bonds acted within a designated cycle of carbon atoms From p 102 benzene according to this view may be represented by a double ring in fact See Armstrong H E 1890 The structure of cycloid hydrocarbons Proceedings of the Chemical Society 6 101 105 Archived from the original on 2021 11 16 Retrieved 2018 02 17 The use of a circle to denote a benzene nucleus first appeared in Armit James Wilson Robinson Robert 1925 Polynuclear heterocyclic aromatic types Part II Some anhydronium bases Journal of the Chemical Society Transactions 127 1604 1618 doi 10 1039 ct9252701604 A history of the determination of benzene s structure is recounted in Balaban Alexandru T Schleyer Paul v R Rzepa Henry S 2005 Crocker Not Armit and Robinson Begat the Six Aromatic Electrons Chemical Reviews 105 10 3436 3447 doi 10 1021 cr0300946 PMID 16218557 Adolf Baeyer 1888 Uber die Constitution des Benzols Justus Liebigs Annalen der Chemie in German vol 245 no 1 2 pp 103 190 doi 10 1002 jlac 18882450110 Thiele Johannes 1899 Zur Kenntnis der ungesattigten Verbindungen On our knowledge of unsaturated compounds Justus Liebig s Annalen der Chemie306 87 142 see VIII Die aromatischen Verbindungen Das Benzol VIII The aromatic compounds Benzene pp 125 129 Archived 2020 03 10 at the Wayback Machine See further Thiele 1901 Zur Kenntnis der ungesattigen Verbindungen Archived 2021 12 26 at the Wayback Machine Justus Liebig s Annalen der Chemie 319 129 143 Loschmidt J 1861 Chemische Studien in German Vienna Austria Hungary Carl Gerold s Sohn pp 30 65 Archived from the original on 2016 05 07 Retrieved 2015 06 27 Kekule F A 1866 Untersuchungen uber aromatische Verbindungen Investigations of aromatic compounds Liebigs Annalen der Chemie und Pharmacie 137 2 129 36 doi 10 1002 jlac 18661370202 Archived from the original on 2021 12 26 Retrieved 2021 12 25 Rocke A J 2010 Image and Reality Kekule Kopp and the Scientific Imagination University of Chicago Press pp 186 227 ISBN 978 0226723358 Archived from the original on 2020 07 27 Retrieved 2020 05 15 Read John 1995 From alchemy to chemistry New York Dover Publications pp 179 180 ISBN 9780486286907 English translation Wilcox David H Greenbaum Frederick R 1965 Kekule s benzene ring theory A subject for lighthearted banter Journal of Chemical Education 42 5 266 67 Bibcode 1965JChEd 42 266W doi 10 1021 ed042p266 Kekule F A 1890 Benzolfest Rede Berichte der Deutschen Chemischen Gesellschaft 23 1302 11 doi 10 1002 cber 189002301204 Archived from the original on 2007 05 16 Retrieved 2007 03 12 Benfey O T 1958 August Kekule and the Birth of the Structural Theory of Organic Chemistry in 1858 Journal of Chemical Education 35 1 21 23 Bibcode 1958JChEd 35 21B doi 10 1021 ed035p21 Gillis Jean 1966 Auguste Kekule et son oeuvre realisee a Gand de 1858 a 1867 Memoires de la Classe des Sciences Academie Royale des Sciences des Lettres et des Beaux arts de Belgique 37 1 1 40 Lonsdale K 1929 The Structure of the Benzene Ring in Hexamethylbenzene Proceedings of the Royal Society 123A 792 494 515 Bibcode 1929RSPSA 123 494L doi 10 1098 rspa 1929 0081 Lonsdale K 1931 An X Ray Analysis of the Structure of Hexachlorobenzene Using the Fourier Method Proceedings of the Royal Society 133A 822 536 553 Bibcode 1931RSPSA 133 536L doi 10 1098 rspa 1931 0166 Archived from the original on 2021 03 19 Retrieved 2007 03 12 Ramos Figueroa Josseline 2021 05 21 Meet Kathleen Lonsdale the physicist and prison reformer who cracked benzene s code Massive Science Retrieved 2022 03 01 Wilhelm Korner 1867 Faits pour servir a la determination du lieu chimique dans la serie aromatique Archived 2017 07 07 at the Wayback Machine Facts to be used in determining chemical location in the aromatic series Bulletins de l Academie royale des sciences des lettres et des beaux arts de Belgique 2nd series 24 166 185 see especially p 169 From p 169 On distingue facilement ces trois series dans lesquelles les derives bihydroxyliques ont leurs terms correspondants par les prefixes ortho para et meta One easily distinguishes these three series in which the dihydroxy derivatives have their corresponding terms by the prefixes ortho para and meta Hermann von Fehling ed Neues Handworterbuch der Chemie New concise dictionary of chemistry Braunschweig Germany Friedrich Vieweg und Sohn 1874 vol 1 p 1142 Graebe 1869 Ueber die Constitution des Naphthalins Archived 2015 11 28 at archive today On the structure of naphthalene Annalen der Chemie und Pharmacie 149 20 28 see especially p 26 Victor Meyer 1870 Untersuchungen uber die Constitution der zweifach substituirten Benzole Archived 2015 10 23 at archive today Investigations into the structure of di substituted benzenes Annalen der Chemie und Pharmacie 156 265 301 see especially pp 299 300 Williams P R D Knutsen J S Atkinson C Madl A K Paustenbach D J 2007 Airborne Concentrations of Benzene Associated with the Historical Use of Some Formulations of Liquid Wrench Journal of Occupational and Environmental Hygiene 4 8 547 561 doi 10 1080 15459620701446642 PMID 17558801 S2CID 32311057 a b Hillis O Folkins 2005 Benzene Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 a03 475 ISBN 978 3527306732 Chang Kenneth June 7 2018 Life on Mars Rover s Latest Discovery Puts It On the Table The New York Times Archived from the original on May 28 2019 Retrieved June 8 2018 The identification of organic molecules in rocks on the red planet does not necessarily point to life there past or present but does indicate that some of the building blocks were present ten Kate Inge Loes June 8 2018 Organic molecules on Mars Science 360 6393 1068 1069 Bibcode 2018Sci 360 1068T doi 10 1126 science aat2662 PMID 29880670 S2CID 46952468 Eigenbrode Jennifer L et al June 8 2018 Organic matter preserved in 3 billion year old mudstones at Gale crater Mars PDF Science 360 6393 1096 1101 Bibcode 2018Sci 360 1096E doi 10 1126 science aas9185 PMID 29880683 S2CID 46983230 Archived PDF from the original on August 25 2021 Retrieved January 4 2021 Bacon G E Curry N Wilson S May 12 1964 A Crystallographic Study of Solid Benzene by Neutron Diffraction Proceedings of the Royal Society of London Series A 279 1376 98 110 Bibcode 1964RSPSA 279 98B doi 10 1098 rspa 1964 0092 ISSN 2053 9169 JSTOR 2414835 S2CID 94432897 Moran D Simmonett AC Leach FE Allen WD Schleyer PV Schaefer HF 2006 Popular Theoretical Methods Predict Benzene and Arenes To Be Nonplanar Journal of the American Chemical Society 128 29 9342 3 doi 10 1021 ja0630285 PMID 16848464 Cooper David L Gerratt Joseph Raimondi Mario 1986 The electronic structure of the benzene molecule Nature 323 6090 699 701 Bibcode 1986Natur 323 699C doi 10 1038 323699a0 S2CID 24349360 Pauling Linus 1987 Electronic structure of the benzene molecule Nature 325 6103 396 Bibcode 1987Natur 325 396P doi 10 1038 325396d0 S2CID 4261220 Messmer Richard P Schultz Peter A 1987 The electronic structure of the benzene molecule Nature 329 6139 492 Bibcode 1987Natur 329 492M doi 10 1038 329492a0 S2CID 45218186 Harcourt Richard D 1987 The electronic structure of the benzene molecule Nature 329 6139 491 492 Bibcode 1987Natur 329 491H doi 10 1038 329491b0 S2CID 4268597 Unicode Character BENZENE RING U 232C fileformat info Archived from the original on 2009 02 19 Retrieved 2009 01 16 Unicode Character BENZENE RING WITH CIRCLE U 23E3 fileformat info Archived from the original on 2009 07 03 Retrieved 2009 01 16 Heterocyclic Chemistry Heterocyclic Compounds Michigan State University Department of Chemistry Archived from the original on 2016 04 06 Retrieved 2016 07 08 Browne Malcolm W August 16 1988 A pervasive molecule is captured in a photograph The New York Times archived from the original on August 12 2021 retrieved August 13 2021 Market Study Benzene 2nd edition Ceresana August 2014 ceresana com Archived from the original on 2017 12 21 Retrieved 2015 02 10 Market Study Toluene Ceresana January 2015 ceresana com Archived from the original on 2017 04 29 Retrieved 2015 02 10 Kolmetz Gentry Guidelines for BTX Revamps AIChE 2007 Spring Conference Control of Hazardous Air Pollutants From Mobile Sources U S Environmental Protection Agency 2006 03 29 p 15853 Archived from the original on 2008 12 05 Retrieved 2008 06 27 Stranks D R M L Heffernan K C Lee Dow P T McTigue G R A Withers 1970 Chemistry A structural view Carlton Victoria Melbourne University Press p 347 ISBN 978 0 522 83988 3 Welch Vincent A Fallon Kevin J Gelbke Heinz Peter 2005 Ethylbenzene Ullmann s Encyclopedia of Industrial Chemistry doi 10 1002 14356007 a10 035 pub2 ISBN 3527306730 Kasper Dennis L et al 2004 Harrison s Principles of Internal Medicine 16th ed McGraw Hill Professional p 618 ISBN 0071402357 Merck Manual Home Edition Archived 2011 09 29 at the Wayback Machine Overview of Leukemia Bard D 2014 Traffic related air pollution and the onset of myocardial infarction disclosing benzene as a trigger A small area case crossover study PLOS ONE 9 6 6 Bibcode 2014PLoSO 9j0307B doi 10 1371 journal pone 0100307 PMC 4059738 PMID 24932584 a b Smith Martyn T 2010 Advances in understanding benzene health effects and susceptibility Annu Rev Public Health 31 133 48 doi 10 1146 annurev publhealth 012809 103646 PMC 4360999 PMID 20070208 American Petroleum Institute API Toxicological Review Benzene September 1948 Agency for Toxic Substances and Disease Registry Department of Health and Human Services Smith Martyn T 2010 01 01 Advances in Understanding Benzene Health Effects and Susceptibility Annual Review of Public Health 31 1 133 148 doi 10 1146 annurev publhealth 012809 103646 PMC 4360999 PMID 20070208 WHO International Agency for Research on Cancer IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Overall Evaluations of Carcinogenicity An Updating of IARC Monographs Archived 2008 03 06 at the Wayback Machine Volumes 1 to 42 Supplement 7 Huff J 2007 Benzene induced cancers abridged history and occupational health impact Int J Occup Environ Health 13 2 213 21 doi 10 1179 oeh 2007 13 2 213 PMC 3363002 PMID 17718179 Rana SV Verma Y 2005 Biochemical toxicity of benzene J Environ Biol 26 2 157 68 PMID 16161967 Agency for Toxic Substances and Disease Registry 2007 Benzene Patient information sheet Archived 2014 12 15 at the Wayback Machine Yardley Jones A Anderson D Parke D V 1991 The toxicity of benzene and its metabolism and molecular pathology in human risk assessment British Journal of Industrial Medicine 48 7 437 44 doi 10 1136 oem 48 7 437 PMC 1035396 PMID 1854646 Occupational Safety and Health Standards Toxic and Hazardous Substances 1910 1028 Archived 2015 06 29 at the Wayback Machine Osha gov Retrieved on 2011 11 23 Public Health Statement for Benzene Agency for Toxic Substances and Disease Registry August 2007 Benzene Patient information sheet Archived 2010 05 28 at the Wayback Machine Atsdr cdc gov 2011 03 03 Retrieved on 2011 11 23 Drinking Water Contaminants Organic Chemicals Benzene United States Environmental Protection Agency EPA Archived from the original on February 2 2015 Retrieved April 17 2014 Chemical Sampling Information Benzene Occupational Safety and Health Administration OSHA Archived from the original on June 29 2015 Retrieved November 23 2011 Benzene Toxicity Standards and Regulations Agency for Toxic Substances and Disease Registry ATSDR Environmental Medicine amp Environmental Health Education CSEM June 30 2000 Archived from the original on June 10 2010 Retrieved October 9 2010 a b NIOSH respirator selection logic PDF Cincinnati Ohio U S Department of Health and Human Services DHHS Public Health Service Centers for Disease Control CDC National Institute for Occupational Safety and Health NIOSH October 2004 Archived from the original PDF on August 29 2017 publication No 2005 100 Documentation for Immediately Dangerous to Life or Health Concentrations IDLH Introduction Centers for Disease Control CDC Archived from the original on April 1 2019 Retrieved November 23 2011 Public Health Statement for Benzene Agency for Toxic Substances and Disease Registry U S Department of Health and Human Services Public Health Service Centers for Disease Control National Institute for Occupational Safety and Health August 2007 Archived from the original on 2012 01 20 Retrieved 2011 11 23 via Atsdr cdc gov Ashley DL Bonin MA Cardinali FL McCraw JM Wooten JV 1994 Blood concentrations of volatile organic compounds in a nonoccupationally exposed US population and in groups with suspected exposure PDF Clinical Chemistry 40 7 Pt 2 1401 4 doi 10 1093 clinchem 40 7 1401 PMID 8013127 Archived PDF from the original on 2011 11 22 Retrieved 2010 08 25 Fustinoni S Buratti M Campo L Colombi A Consonni D Pesatori AC Bonzini M Farmer P Garte S Valerio F Merlo DF Bertazzi PA 2005 Urinary t t muconic acid S phenylmercapturic acid and benzene as biomarkers of low benzene exposure Chemico Biological Interactions 153 154 253 6 doi 10 1016 j cbi 2005 03 031 PMID 15935823 ACGIH 2009 2009 TLVs and BEIs American Conference of Governmental Industrial Hygienists Cincinnati Ohio Baselt R 2008 Disposition of Toxic Drugs and Chemicals in Man 8th edition Biomedical Publications Foster City CA pp 144 148 ISBN 0962652377 Snyder R Hedli C C 1996 An overview of benzene metabolism Environ Health Perspect 104 Suppl 6 1165 1171 doi 10 1289 ehp 96104s61165 PMC 1469747 PMID 9118888 Dougherty D Garte S Barchowsky A Zmuda J Taioli E 2008 NQO1 MPO CYP2E1 GSTT1 and STM1 polymorphisms and biological effects of benzene exposure a literature review Toxicology Letters 182 1 3 7 17 doi 10 1016 j toxlet 2008 09 008 PMID 18848868 Fracasso ME Doria D Bartolucci GB Carrieri M Lovreglio P Ballini A Soleo L Tranfo G Manno M 2010 Low air levels of benzene Correlation between biomarkers of exposure and genotoxic effects Toxicol Lett 192 1 22 8 doi 10 1016 j toxlet 2009 04 028 PMID 19427373 Eastmond D A Rupa DS Hasegawa LS 2000 Detection of hyperdiploidy and chromosome breakage in interphase human lymphocytes following exposure to the benzene metabolite hydroquinone using multicolor fluorescence in situ hybridization with DNA probes Mutat Res 322 1 9 20 doi 10 1016 0165 1218 94 90028 0 PMID 7517507 Garte S Taioli E Popov T Bolognesi C Farmer P Merlo F 2000 Genetic susceptibility to benzene toxicity in humans J Toxicol Environ Health A 71 22 1482 1489 doi 10 1080 15287390802349974 PMID 18836923 S2CID 36885673 ToxFAQs for Benzene Agency for Toxic Substances and Disease Registry Department of Health and Human Services Archived 2008 03 09 at the Wayback Machine ToxGuide for Benzene Archived 2010 05 28 at the Wayback Machine Agency for Toxic Substances and Disease Registry Department of Health and Human Services Public Health Statement Benzene Archived 2010 05 27 at the Wayback Machine Division of Toxicology and Environmental Medicine August 2007 Benzene CASRN 71 43 2 Archived 2011 10 22 at the Wayback Machine Hazardous Substances Data Bank U S National Library of Medicine National Institutes of Health FDA Too Much Benzene In Some Drinks Archived 2007 02 18 at the Wayback Machine CBS News May 19 2006 Retrieved July 11 2006 100 tonnes of pollutants spilled into Chinese river The Guardian 25 November 2005 Archived from the original on 10 March 2020 Retrieved 7 January 2020 Isaacson Kristofer P Proctor Caitlin R Wang Q Erica Edwards Ethan Y Noh Yoorae Shah Amisha D Whelton Andrew J 2021 Drinking water contamination from the thermal degradation of plastics Implications for wildfire and structure fire response Environmental Science Water Research amp Technology 7 2 274 284 doi 10 1039 D0EW00836B Selections and lethal injections Auschwitz Birkenau State Museum Archived from the original on May 9 2020 Retrieved May 15 2020 A Former Nazi Labor Camp in Austria Now Billed as a Tourist Site Haaretz May 3 2019 Archived from the original on May 11 2019 Retrieved May 11 2019 External links Edit Wikimedia Commons has media related to Benzene category Look up benzene in Wiktionary the free dictionary Wikiquote has quotations related to Benzene Scholia has a chemical profile for Benzene Benzene at The Periodic Table of Videos University of Nottingham International Chemical Safety Card 0015 USEPA Summary of Benzene Toxicity NIOSH Pocket Guide to Chemical Hazards Benzene from PubChem Dept of Health and Human Services TR 289 Toxicology and Carcinogenesis Studies of Benzene Video Podcast of Sir John Cadogan giving a lecture on Benzene since Faraday in 1991 Substance profile Benzene in the ChemIDplus database NLM Hazardous Substances Databank Benzene Retrieved from https en wikipedia org w index php title Benzene amp oldid 1144405049, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.