7999. Pyrocatechol

Nomenclature

CAS number: 120-80-9
1,2-Benzenediol; pyrocatechin; catechol; 1,2-dihydroxybenzene.
C6H6O2; mol wt 110.11.
C 65.45%, H 5.49%, O 29.06%.

Description and references

Prepd by treating salicylaldehyde with hydrogen peroxide, or from its monomethyl ether (guaiacol) by treatment with hydrobromic acid: Dakin, Org. Synth. coll. vol. I, 149 (2nd ed., 1941). Toxicity data: A. J. Lehman et al., Adv. Food Res. 3, 197 (1951). Carcinogenicity study: M. Hirose et al., Carcinogenesis 14, 525 (1993). Review: J. Varagnat, “Hydroquinone, Resorcinol, and Catechol”, in Kirk-Othmer Encyclopedia of Chemical Technology vol. 13 (Wiley-Interscience, New York, 3rd ed., 1981) pp 39-69.

Chemical structure

Properties

Monoclinic tablets, prisms from toluene. Discolors in air and light. d 1.344; mp 105°; bp760 245.5°; bp400 221.5°; bp200 197.7°; bp100 176°; bp60 161.7°; bp40 150.6°; bp20 134°; bp10 118.3°; bp5 104°. Sublimes. Volatile with steam. pK (18°) 9.48. Sol in 2.3 parts water, in alcohol, benzene, chloroform, ether; very sol in pyridine, aq alkalies. Its aq solns soon turn brown. LD50 in mice (mg/kg): 260 orally; 190 i.p. (Lehman).

Note

Catechol also refers to catechin, q.v.

Caution

Potential symptoms of overexposure are irritation of eyes, skin, respiratory system; lacrimation, eye burns; convulsions, increased blood pressure. Direct contact may cause skin sensitization and dermatitis. Systemic effects similar to phenol, q.v. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 56; Patty's Industrial Hygiene and Toxicology vol. 2B, G. D. Clayton, F. E. Clayton, Eds. (Wiley-Interscience, New York, 4th ed., 1994) pp 1584-1586.

Use

In photography; dyeing fur; as reagent.

Therapeutic Category

Antiseptic.