Benzidine is prepared in a two step process from nitrobenzene. First, the nitrobenzene is converted to 1,2-diphenylhydrazine, usually using iron powder as the reducing agent. Treatment of this hydrazine with mineral acids induces a rearrangement reaction to 4,4'-benzidine. Smaller amounts of other isomers are also formed.[3] The benzidine rearrangement, which proceeds intramolecularly, is a classic mechanistic puzzle in organic chemistry.[4]
In terms of its physical properties, 4,4'-benzidine is poorly soluble in cold water but can be recrystallized from hot water, where it crystallises as the monohydrate. It is dibasic, the deprotonated species has Ka values of 9.3 × 10−10 and 5.6 × 10−11. Its solutions react with oxidizing agents to give deeply coloured quinone-related derivatives.
Applicationsedit
Conversion of benzidine to the bis(diazonium) salt was once an integral step in the preparation of direct dyes (requiring no mordant). Treatment of this bis(diazonium) salt with 1-aminonaphthalene-4-sulfonic acid gives the once popular congo red dye. In the past, benzidine was used to test for blood. An enzyme in blood causes the oxidation of benzidine to a distinctively blue-coloured derivative. The test for cyanide relies on similar reactivity. Such applications have largely been replaced by methods using phenolphthalein/hydrogen peroxide and luminol.
The popular dye congo red is derived from benzidine.
Related 4,4’-benzidinesedit
A variety of derivatives of 4,4’-benzidine are commercially produced on the scale of one to a few thousand kilograms per year, mainly as precursors to dyes and pigments.[3] These derivatives include, in order of scale, the following:
As with some other aromatic amines such as 2-naphthylamine, benzidine has been significantly withdrawn from use in most industries because it is so carcinogenic. In August 2010 benzidine dyes were included in the U.S. EPA's List of Chemicals of Concern.[7] The manufacture of Benzidine has been illegal in the UK since at least 2002 under the Control of Substances Hazardous to Health Regulations 2002 (COSHH).
^March, J. (1992). Advanced Organic Chemistry (5th ed.). New York: J. Wiley and Sons. ISBN0-471-60180-2.
^Shine, H. J.; Zmuda, H.; Park, K. H.; Kwart, H.; Horgan, A. G.; Collins, C.; Maxwell, B. E. (1981). "Mechanism of the benzidine rearrangement. Kinetic isotope effects and transition states. Evidence for concerted rearrangement". Journal of the American Chemical Society. 103 (4): 955–956. doi:10.1021/ja00394a047..
^Shine, H. J.; Zmuda, H.; Park, K. H.; Kwart, H.; Horgan, A. G.; Brechbiel, M. (1982). "Benzidine rearrangements. 16. The use of heavy-atom kinetic isotope effects in solving the mechanism of the acid-catalyzed rearrangement of hydrazobenzene. The concerted pathway to benzidine and the nonconcerted pathway to diphenyline". Journal of the American Chemical Society. 104 (9): 2501–2509. doi:10.1021/ja00373a028.
^. U. S. Environmental Protection Agency. 2010-08-18. Archived from the original on 2010-08-21.
February 06, 2024
benzidine, trivial, name, also, called, biphenyl, diamine, systematic, name, organic, compound, with, formula, c6h4nh2, aromatic, amine, component, test, cyanide, related, derivatives, used, production, dyes, been, linked, bladder, pancreatic, cancer, namespre. Benzidine trivial name also called 1 1 biphenyl 4 4 diamine systematic name is an organic compound with the formula C6H4NH2 2 It is an aromatic amine It is a component of a test for cyanide Related derivatives are used in the production of dyes Benzidine has been linked to bladder and pancreatic cancer 2 Benzidine NamesPreferred IUPAC name 1 1 Biphenyl 4 4 diamineOther names Benzidine di phenylamine diphenylamine 4 4 bianiline 4 4 biphenyldiamine 1 1 biphenyl 4 4 diamine 4 4 diaminobiphenyl p diaminodiphenyl p benzidineIdentifiersCAS Number 92 87 5 Y3D model JSmol Interactive imageChEBI CHEBI 80495 NChEMBL ChEMBL15901 YChemSpider 6844 YECHA InfoCard 100 002 000EC Number 202 199 1KEGG C16444 YPubChem CID 7111RTECS number DC9625000UNII 2X02101HVF YUN number 1885CompTox Dashboard EPA DTXSID2020137InChI InChI 1S C12H12N2 c13 11 5 1 9 2 6 11 10 3 7 12 14 8 4 10 h1 8H 13 14H2 YKey HFACYLZERDEVSX UHFFFAOYSA N YInChI 1 C12H12N2 c13 11 5 1 9 2 6 11 10 3 7 12 14 8 4 10 h1 8H 13 14H2Key HFACYLZERDEVSX UHFFFAOYAXSMILES c2c c1ccc N cc1 ccc N c2PropertiesChemical formula C12H12N2Molar mass 184 24 g molAppearance Grayish yellow reddish gray or white crystalline powder 1 Density 1 25 g cm3Melting point 122 to 125 C 252 to 257 F 395 to 398 K Boiling point 400 C 752 F 673 K Solubility in water 0 94 g 100 mL at 100 CMagnetic susceptibility x 110 9 10 6 cm3 molRelated compoundsRelated compounds biphenylHazardsOccupational safety and health OHS OSH Main hazards carcinogenicGHS labelling PictogramsSignal word DangerHazard statements H302 H350 H410Precautionary statements P201 P202 P264 P270 P273 P281 P301 P312 P308 P313 P330 P391 P405 P501NIOSH US health exposure limits PEL Permissible occupational carcinogen 1 Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa N verify what is Y N Infobox references Contents 1 Synthesis and properties 2 Applications 3 Related 4 4 benzidines 4 Safety 5 ReferencesSynthesis and properties editBenzidine is prepared in a two step process from nitrobenzene First the nitrobenzene is converted to 1 2 diphenylhydrazine usually using iron powder as the reducing agent Treatment of this hydrazine with mineral acids induces a rearrangement reaction to 4 4 benzidine Smaller amounts of other isomers are also formed 3 The benzidine rearrangement which proceeds intramolecularly is a classic mechanistic puzzle in organic chemistry 4 nbsp The conversion is described as a 5 5 sigmatropic reaction 5 6 nbsp In terms of its physical properties 4 4 benzidine is poorly soluble in cold water but can be recrystallized from hot water where it crystallises as the monohydrate It is dibasic the deprotonated species has Ka values of 9 3 10 10 and 5 6 10 11 Its solutions react with oxidizing agents to give deeply coloured quinone related derivatives Applications editConversion of benzidine to the bis diazonium salt was once an integral step in the preparation of direct dyes requiring no mordant Treatment of this bis diazonium salt with 1 aminonaphthalene 4 sulfonic acid gives the once popular congo red dye In the past benzidine was used to test for blood An enzyme in blood causes the oxidation of benzidine to a distinctively blue coloured derivative The test for cyanide relies on similar reactivity Such applications have largely been replaced by methods using phenolphthalein hydrogen peroxide and luminol nbsp The popular dye congo red is derived from benzidine Related 4 4 benzidines editA variety of derivatives of 4 4 benzidine are commercially produced on the scale of one to a few thousand kilograms per year mainly as precursors to dyes and pigments 3 These derivatives include in order of scale the following 3 3 Dichlorobenzidine o tolidine 3 3 dimethyl 4 4 benzidine o dianisidine 3 3 dimethoxy 4 4 benzidine CAS 119 90 4 m p 133 C 3 3 4 4 Tetraamino diphenyl precursor to polybenzimidazole fiber Safety editAs with some other aromatic amines such as 2 naphthylamine benzidine has been significantly withdrawn from use in most industries because it is so carcinogenic In August 2010 benzidine dyes were included in the U S EPA s List of Chemicals of Concern 7 The manufacture of Benzidine has been illegal in the UK since at least 2002 under the Control of Substances Hazardous to Health Regulations 2002 COSHH References edit a b NIOSH Pocket Guide to Chemical Hazards 0051 National Institute for Occupational Safety and Health NIOSH Known and Probable Carcinogens American Cancer Society 2011 06 29 Archived from the original on 2008 03 17 Retrieved 2007 01 12 a b Schwenecke H Mayer D 2005 Benzidine and Benzidine Derivatives Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 a03 539 ISBN 978 3527306732 March J 1992 Advanced Organic Chemistry 5th ed New York J Wiley and Sons ISBN 0 471 60180 2 Shine H J Zmuda H Park K H Kwart H Horgan A G Collins C Maxwell B E 1981 Mechanism of the benzidine rearrangement Kinetic isotope effects and transition states Evidence for concerted rearrangement Journal of the American Chemical Society 103 4 955 956 doi 10 1021 ja00394a047 Shine H J Zmuda H Park K H Kwart H Horgan A G Brechbiel M 1982 Benzidine rearrangements 16 The use of heavy atom kinetic isotope effects in solving the mechanism of the acid catalyzed rearrangement of hydrazobenzene The concerted pathway to benzidine and the nonconcerted pathway to diphenyline Journal of the American Chemical Society 104 9 2501 2509 doi 10 1021 ja00373a028 Benzidine Dyes Action Plan Summary U S Environmental Protection Agency 2010 08 18 Archived from the original on 2010 08 21 Retrieved from https en wikipedia org w index php title Benzidine amp oldid 1178764351, wikipedia, wiki, book, books, library,
