GB483308A - Manufacture of isocyanates - Google Patents

Abstract

Isocyanates are obtained by the action of phosgene on amines of the formula RXR1NH2, where R is an alkyl group of at least seven carbon atoms, X is -CH2-, -O-, -S-, or -OOC-, and R1 is a residue of the benzene series, which may be substituted, e.g. by halogen or an alkyl, alkoxy or nitro group; the amines may be treated as such or in the form of their salts. The reaction is preferably effected at about 50-70 DEG C. in the presence of a diluent, e.g. benzene or toluene. Examples are given of the preparation of (1) p-cetylphenyl isocyanate from p-cetylaniline hydrochloride or oxalate; (2) p-dodecylphenyl isocyanate from p-dodecylaniline or its hydrochloride; (3) 2-methyl-4-dodecylphenyl isocyanate from 2-methyl - 4 - dodecylaniline hydrochloride; (4) 3-nitro-4-dodecylphenyl isocyanate from 3-nitro - 4 - dodecylaniline hydrochloride; (5) 2-nitro-4-dodecylphenyl isocyanate from 2-nitro - 4 - dodecylaniline hydrochloride; (6) p-cetyloxyphenyl isocyanate from p-aminophenyl cetyl ether hydrochloride; (7) p-dodecylthiophenyl isocyanate from p-aminophenyl dodecyl sulphide hydrochloride; and (8) p-carbododecyloxyphenyl isocyanate from dodecyl p-aminobenzoate hydrochloride; the formation of ureas by the reaction of aniline with the products of examples 3-8 above is mentioned. Specifications 466,127, 468,226, and 469,080 are referred to. p-Cetylaniline oxalate is obtainable from equimolecular proportions of p-cetylaniline and oxalic acid in ether. p-Aminophenyl cetyl ether is obtained by treating sodium p-acetaminophenolate with cetyl bromide and hydrolyzing the product. p-Aminophenyl dodecyl sulphide hydrochloride is obtained by the action of stannous chloride and hydrochloric acid on p-nitrophenyl dodecyl sulphide, which is itself obtained from p-nitrothiophenol and dodecyl bromide in the presence of sodium ethylate.