GB439055A - Improvements in or relating to the manufacture of amines - Google Patents

Abstract

In the manufacture of nitroarylamines by the action of ammonia on nitroaryl halides, having at least one halogen atom and one nitro group in o- or p-position to one another, in a vessel in which the part in contact with the reaction mixture is subject to iron corrosion, the corrosion of the vessel is inhibited by adding to the reaction mixture a secondary or tertiary arylamine, aralkylamine, alkylarylamine, or heterocyclic amine, or a guanidine or a thiourea. Specified inhibitors are dibenzylaniline, diethyl-1 - naphthylamine, monoethyl - m - toluidine, ethyl - o - toluidine, dimethyl - m - toluidine, monoethylaniline, dimethylaniline, pyridine, quinoline, isoquinoline, thiocarbanilide, diphenylguanidine, di-o-tolylguanidine, and diphenylamine. The reaction may be effected with aqueous or anhydrous ammonia and in the presence or absence of an auxiliary acid-binding agent such as sodium carbonate or bicarbonate. In the examples: (1) p-nitrochlorobenzene is heated with aqueous ammonia in a steel autoclave with the addition of pyridine or (2) a mixture of pyridine bases or (3) dimethylaniline; p-nitraniline is obtained; (4) o-nitraniline is obtained from o-nitrochlorobenzene as in example 1; (5) 4-chloro-2-nitraniline is obtained from 2 : 5-dichloronitrobenzene as in example 1; (6) 2 : 4-dinitrochlorobenzene is heated with aqueous ammonia in an iron autoclave with the addition of quinoline; 2 : 4-dinitraniline is obtained; (7) 4-nitrochlorobenzene-2-sulphonic acid is heated with aqueous ammonia in an iron autoclave with the addition of ethyl-o-toluidine and sodium carbonate; 4-nitraniline -2-sulphonic acid is obtained. Other nitroarylamines similarly obtainable from the corresponding nitroaryl halides are 4-nitro-1-naphthylamine, 3 - methoxy - 4 - nitraniline, 3 - nitro - 4 - aminodiphenyl, 2 - nitraniline - 4 - sulphonic acid, 2 - nitro - 4 - bromoaniline, 3 - nitro - 4 - aminotoluene, 2 : 4 - dinitraniline - 6 - sulphonic acid, and 2 : 4 : 6 - trinitraniline. The Specification as open to inspection under Sect. 91 states that the nitro group in the starting materials may be replaced by another "activating substituent." This statement does not appear in the Specification as accepted.