Abstract

Diarylamines are compounds that have two aromatic groups and one hydrogen atom attached to nitrogen. Diphenylamine (DPA) or N-phenylbenzenamine, is the most commercially significant diarylamine. It is manufactured by heating aniline by itself, or with phenol, and with an acid catalyst at high temperatures. It is used as a stabilizer for nitrocellulose propellants. When alkylated, diphenylamine finds its largest application as an antioxidant and stabilizer for oils, greases, polymers, and elastomers. Diarylamines that contain other functional groups, such as hydroxyl or amino, are useful dye intermediates, antiozonants, hair dyes, and color photography intermediates. Important reactions of diarylamines include C-alkylation and oxidation. Diarylamines are manufactured by the self-condensation of a primary aromatic amine in the presence of an acid, or the reaction of an arylamine with a phenol at high temperatures. Industrial poisoning by diphenylamine has been encountered and appears clinically as bladder symptoms, tachycardia, hypertension, and skin problems. There is no federal standard for permissible exposure limits in air, but the American Conference of Government Industrial Hygienists (1983/1984) has adopted a time-weighted average value of 10 mg/m³ and set a short-term exposure limit of 20 mg/m³. N-Nitrosodiphenylamine can act as a nitrosating agent for other amines. Diarylamines based on polycyclic aromatic amines also tend to be more harmful.