2-Naphthylamine

2-Naphthylamine is one of two isomeric aminonaphthalenes, compounds with the formula C10H7NH2. It is a colorless solid, but samples take on a reddish color in air because of oxidation. It was formerly used to make azo dyes, but it is a known carcinogen and has largely been replaced by less toxic compounds.[2]

2-Naphthylamine
Names
Preferred IUPAC name
Naphthalen-2-amine
Other names
(Naphthalen-2-yl)amine
2-Naphthylamine
β-Naphthylamine
Identifiers
3D model (JSmol)
606264
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.892
EC Number
  • 202-080-4
165176
KEGG
RTECS number
  • QM2100000
UNII
UN number 1650
Properties
C10H9N
Molar mass 143.189 g·mol−1
Appearance White to red crystals[1]
Odor odorless[1]
Density 1.061 g/cm3
Melting point 111 to 113 °C (232 to 235 °F; 384 to 386 K)
Boiling point 306 °C (583 °F; 579 K)
miscible in hot water[1]
Vapor pressure 1 mmHg (107° C)[1]
Acidity (pKa) 3.92
-98.00·10−6 cm3/mol
Hazards
GHS pictograms
GHS Signal word Danger
H302, H350, H411
P201, P202, P264, P270, P273, P281, P301+312, P308+313, P330, P391, P405, P501
Flash point 157 °C; 315 °F; 430 K
Related compounds
Related compounds
 2-Naphthol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Preparation

2-Naphthylamine is prepared by heating 2-naphthol with ammonium zinc chloride to 200-210 °C, the Bucherer reaction. It's acetyl derivative can be obtained by heating 2-naphthol with ammonium acetate to 270-280 °C.

Reactions

It gives no color with iron(III) chloride. When reduced by sodium in boiling amyl alcohol solution, it forms tetrahydro-3-naphthylamine, which exhibits the properties of the aliphatic amines in that it is strongly alkaline in reaction, has an ammoniacal odor and cannot be diazotized.

On oxidation, it yields ortho-carboxy-hydrocinnamic acid, HO2CC6H4CH2CH2CO2H.

Numerous sulfonic acid derivatives of 2-naphthylamine are used in commerce, such as precursors to dyes.[2] Owing to the carcinogenicity of the amine, these derivatives are mainly prepared by amination of the corresponding naphthols. Of them, the δ-acid and Bronner's acid are of more value technically, since they combine with ortho-tetrazoditolyl to produce fine red dye-stuffs.

2-Naphthylamine was previously used as a dye precursor and rubber antioxidant in the 1930s, 40s and 50s. Dupont stopped using it in the 1970s.[3]

Role in disease

2-Naphthylamine is found in cigarette smoke and suspected to contribute to the development of bladder cancer.[4]

It is activated in the liver but quickly deactivated by conjugation to glucuronic acid. In the bladder, glucuronidase re-activates it by deconjugation, which leads to the development of bladder cancer.

See also

References
  2. Gerald Booth "Naphthalene Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a17_009.
  3. Castleman, Barry (1979), Dupont's Record In Business Ethics: Another View, Washington Post, July 15th 1979
  4. CDC - NIOSH Pocket Guide to Chemical Hazards
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