2-Naphthol, or β-naphthol, is a fluorescent colorless (or occasionally yellow) crystalline solid with the formula C10H7OH. It is an isomer of 1-naphthol, differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are naphthalene homologues of phenol, but more reactive. Both isomers are soluble in simple alcohols, ethers, and chloroform. 2-Naphthol is a widely used intermediate for the production of dyes and other compounds.
Traditionally, 2-naphthol is produced by a two-step process that begins with the sulfonation of naphthalene in sulfuric acid:[2]
C10H8 + H2SO4 → C10H7SO3H + H2O
The sulfonic acid group is then cleaved in molten sodium hydroxide:
C10H7(SO3H) + 3 NaOH → C10H7ONa + Na2SO3 + 2 H2O
Neutralization of the product with acid gives 2-naphthol.
2-Naphthol can also be produced by a method analogous to the cumene process.[2]
2-Naphthol-derived dyesedit
The Sudan dyes are popular dyes noted for being soluble in organic solvents. Several of the Sudan dyes are derived from 2-naphthol by coupling with diazonium salts.[3] Sudan dyes I–IV and Sudan Red G consist of arylazo-substituted naphthols.
Electrophilic attack occurs characteristically at the 1-position as indicated by nitrosylation to give 1-nitroso-2-naphthol.[6] Bromination[7] and alkylations proceed with similar regiochemistry.[8] Ring-opening reactions have been documented.[9]
^Booth, Gerald; Zollinger, Heinrich; McLaren, Keith; Sharples, William G.; Westwell, Alan (2000). "Dyes, General Survey". Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH. doi:10.1002/14356007.a09_073. ISBN9783527306732.
^Melvin S. Newman; Frederick W. Hetzel (1971). "Thiophenols from Phenols: 2-Naphthalenethiol". Organic Syntheses. 51: 139. doi:10.15227/orgsyn.051.0139.
^J. P. Schaefer; Jerry Higgins; P. K. Shenoy (1969). "2-Bromonaphthalene". Organic Syntheses. 49: 6. doi:10.15227/orgsyn.049.0006.
^Marvel, C. S.; Porter, P. K. (1922). "Nitroso-β-Naphthol". Organic Syntheses. 2: 61. doi:10.15227/orgsyn.002.0061.
^C. Frederick Koelsch (1940). "6-Bromo-2-Naphthol". Organic Syntheses. 20: 18. doi:10.15227/orgsyn.020.0018.
^Alfred Russell Luther B. Lockhart (1942). "2-Hydroxy-1-Naphthaldehyde". Organic Syntheses. 22: 63. doi:10.15227/orgsyn.022.0063.
^G. A. Page, D. S. Tarbell (1954). "β-(o-Carboxyphenyl)propionic Acid". Organic Syntheses. 34: 8. doi:10.15227/orgsyn.034.0008.
naphthol, naphthol, fluorescent, colorless, occasionally, yellow, crystalline, solid, with, formula, c10h7oh, isomer, naphthol, differing, location, hydroxyl, group, naphthalene, ring, naphthols, naphthalene, homologues, phenol, more, reactive, both, isomers, . 2 Naphthol or b naphthol is a fluorescent colorless or occasionally yellow crystalline solid with the formula C10H7OH It is an isomer of 1 naphthol differing by the location of the hydroxyl group on the naphthalene ring The naphthols are naphthalene homologues of phenol but more reactive Both isomers are soluble in simple alcohols ethers and chloroform 2 Naphthol is a widely used intermediate for the production of dyes and other compounds 2 Naphthol Names Preferred IUPAC name Naphthalen 2 ol Other names 2 Hydroxynaphthalene 2 Naphthalenol beta Naphthol Naphth 2 ol Identifiers CAS Number 135 19 3 Y 3D model JSmol Interactive imageInteractive image Beilstein Reference 742134 ChEBI CHEBI 10432 Y ChEMBL ChEMBL14126 Y ChemSpider 8341 Y ECHA InfoCard 100 004 712 EC Number 205 182 7 Gmelin Reference 27395 KEGG C11713 Y PubChem CID 8663 RTECS number QL2975000 UNII P2Z71CIK5H Y UN number 3077 CompTox Dashboard EPA DTXSID5027061 InChI InChI 1S C10H8O c11 10 6 5 8 3 1 2 4 9 8 7 10 h1 7 11H YKey JWAZRIHNYRIHIV UHFFFAOYSA N YInChI 1 C10H8O c11 10 6 5 8 3 1 2 4 9 8 7 10 h1 7 11HKey JWAZRIHNYRIHIV UHFFFAOYAV SMILES Oc2ccc1c cccc1 c2c1ccc2cc ccc2c1 O Properties Chemical formula C 10H 8O Molar mass 144 173 g mol 1 Appearance Colorless crystalline solid Density 1 280 g cm3 Melting point 121 to 123 C 250 to 253 F 394 to 396 K Boiling point 285 C 545 F 558 K Solubility in water 0 74 g L Acidity pKa 9 51 Magnetic susceptibility x 98 25 10 6 cm3 mol Hazards Occupational safety and health OHS OSH Main hazards Harmful when inhaled or swallowed dangerous to environment esp aquatic organisms 1 GHS labelling Pictograms Signal word Warning Hazard statements H302 H332 H400 Precautionary statements P261 P264 P270 P271 P273 P301 P312 P304 P312 P304 P340 P312 P330 P391 P501 NFPA 704 fire diamond 210 Flash point 161 C 322 F 434 K 1 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 Contents 1 Production 2 2 Naphthol derived dyes 3 Reactions 4 Safety 5 References 6 External linksProduction editTraditionally 2 naphthol is produced by a two step process that begins with the sulfonation of naphthalene in sulfuric acid 2 C10H8 H2SO4 C10H7SO3H H2O The sulfonic acid group is then cleaved in molten sodium hydroxide C10H7 SO3H 3 NaOH C10H7ONa Na2SO3 2 H2O Neutralization of the product with acid gives 2 naphthol 2 Naphthol can also be produced by a method analogous to the cumene process 2 2 Naphthol derived dyes editThe Sudan dyes are popular dyes noted for being soluble in organic solvents Several of the Sudan dyes are derived from 2 naphthol by coupling with diazonium salts 3 Sudan dyes I IV and Sudan Red G consist of arylazo substituted naphthols Selected 2 Naphthol derived dyes nbsp Sudan I nbsp Sudan II nbsp Sudan III nbsp Sudan IV nbsp Oil Red O nbsp Naphthol ASReactions editSome reactions of 2 naphthol are explicable with reference to its tautomerism which produces a small amount of the keto tautomer nbsp Tautomeric equilibrium for beta naphthol One consequence of this tautomerism is the Bucherer reaction the ammonolysis of 2 naphthol to give 2 aminonaphthalene 2 Naphthol can be oxidatively coupled to form BINOL a C2 symmetric ligand popularized for use in asymmetric catalysis nbsp Coupling of beta naphthol using CuCl2 2 Naphthol converts to 2 naphthalenethiol by reaction with dimethylthiocarbamoyl chloride via the Newman Kwart rearrangement 4 The OH Br conversion has been described 5 Electrophilic attack occurs characteristically at the 1 position as indicated by nitrosylation to give 1 nitroso 2 naphthol 6 Bromination 7 and alkylations proceed with similar regiochemistry 8 Ring opening reactions have been documented 9 Carbonation of 2 naphthol gives 2 hydroxy 1 naphthoic acid 2 Safety edit2 Naphthol has been described as moderately toxic 2 References edit a b MSDS safety data for 2 naphthol Archived from the original on 3 March 2011 a b c d Booth Gerald 2005 Naphthalene Derivatives Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 a17 009 ISBN 978 3527306732 full text PDF Booth Gerald Zollinger Heinrich McLaren Keith Sharples William G Westwell Alan 2000 Dyes General Survey Ullmann s Encyclopedia of Industrial Chemistry Wiley VCH doi 10 1002 14356007 a09 073 ISBN 9783527306732 Melvin S Newman Frederick W Hetzel 1971 Thiophenols from Phenols 2 Naphthalenethiol Organic Syntheses 51 139 doi 10 15227 orgsyn 051 0139 J P Schaefer Jerry Higgins P K Shenoy 1969 2 Bromonaphthalene Organic Syntheses 49 6 doi 10 15227 orgsyn 049 0006 Marvel C S Porter P K 1922 Nitroso b Naphthol Organic Syntheses 2 61 doi 10 15227 orgsyn 002 0061 C Frederick Koelsch 1940 6 Bromo 2 Naphthol Organic Syntheses 20 18 doi 10 15227 orgsyn 020 0018 Alfred Russell Luther B Lockhart 1942 2 Hydroxy 1 Naphthaldehyde Organic Syntheses 22 63 doi 10 15227 orgsyn 022 0063 G A Page D S Tarbell 1954 b o Carboxyphenyl propionic Acid Organic Syntheses 34 8 doi 10 15227 orgsyn 034 0008 External links editNIST Chemistry WebBook 2 Naphthalenol Napthols Encyclopaedia Britannica Vol 19 11th ed 1911 pp 168 169 Retrieved from https en wikipedia org w index php title 2 Naphthol amp oldid 1218796264, wikipedia, wiki, book, books, library,
