Patent GB-416579-A (GB)
Title: Manufacture of 4-aminodiphenylamine derivatives
IPC: A01J5/02
Filed: 1933-03-09
Abstract: 3 - Alkyl (or 3 - alkoxy) - 4 - aminodiphenylamines are prepared (1) by coupling a 3-alkyl (or 3-alkoxy)-diphenylamine, unsubstituted in the 4-position, with a diazo compound and reducing the azo dye so obtained, or (2) by converting a 3 - alkyl (or 3 - alkoxy)-diphenylamine, unsubstituted in the 4-position, into its N-nitroso derivative, treating the latter in known manner to transfer the nitroso group to the nucleus, and reducing the product, or (3) by nitrating a N-acyl-3-alkyl (or 3-alkoxy)-diphenylamine, unsubstituted in the 4-position, and subjecting the product to saponification and reduction in either order.  In the examples: (1) diazotized sulphanilic acid is treated with a solution of 3-methoxydiphenylamine in xylene and pyridine, and the dye so obtained is reduced with zinc and caustic soda solution; 3 - methoxy - 4 - amino - diphenylamine is obtained; (2) the diazo compound from sulphanilic acid is isolated by filtration, washed with sodium chloride solution, and treated in alcoholic suspension with 3-methoxy-3<1>-chlorodiphenylamine in the presence of hydrochloric acid; the dye so obtained is reduced with a boiling alkaline solution of sodium trisulphide, yielding 4 - amino - 3 - methoxy - 3<1> - chlorodiphenylamine; the product is identical with that obtainable by condensing 2 : 4-dichlorobenzoic acid with 1-amino - 4 - acetylamino - 3 - methoxybenzene and splitting off the carboxyl and acetyl groups; an acetyl derivative of the product is described; (3) an alcoholic suspension of the diazo compound from sulphanilic acid is treated with 3-methyldiphenylamine in the presence of hydrochloric acid, and the dye so obtained is reduced with alkaline sodium hydrosulphite solution to produce 3-methyl-4-aminodiphenylamine; (4) 3-methoxydiphenylamine is converted by the standard process into its N-nitroso derivative, which is treated with hydrochloric acid in the cold to produce 3 - methoxy - 4 - nitrosodiphenylamine; the latter is reduced with alkaline sodium polysulphide solution, yielding 3-methoxy-4-aminodiphenylamine; (5) 3 - methoxy - N - benzoyldiphenylamine is nitrated to produce the 4-nitro compound, which is warmed with alcoholic caustic potash to which zinc dust is afterwards added; 3 - methoxy - 4 - aminodiphenylamine is obtained; the same product is obtainable similarly from 3 - methoxy - N - formyldiphenylamine.  The Specification as open to inspection under Sect. 91 comprises also the following four examples: (1) 3 - methyl - 4 - nitrosodiphenylamine, prepared as in example 4 above from 3-methyldiphenylamine, is reduced as in example 4 above to 3 - methyl - 4 - aminodiphenylamine; (2) 3 - methoxy - 3<1> - methyldiphenylamine is converted into its N-nitroso derivative, which is treated with alcoholic hydrochloric acid to produce 4 - nitroso - 3 - methoxy - 3<1> - methyldiphenylamine; the latter is reduced with alkaline sodium sulphide solution to 4-amino-3-methoxy - 3<1> - methyldiphenylamine; an acetyl derivative of the product is described; 4-amino-3 : 2<1>-dimethoxydiphenylamine and 4-amino-3-methoxy - 2<1> - ethoxydiphenylamine are obtainable similarly; (3) 3-ethoxydiphenylamine is boiled with acetic anhydride, and the product is nitrated to produce 3-ethoxy-4-nitro-N-acetyldiphenylamine; the latter is saponified and reduced by boiling with alcoholic caustic potash and zinc dust, yielding 3-ethoxy-4-aminodiphenylamine; (4) 3-methoxy-3<1>-chloro-N-acetyldiphenylamine is successively nitrated, reduced, and saponified to produce 4-amino-3-methoxy - 3<1> - chlorodiphenylamine.  The following substitution products of 4-aminodiphenylamine are also obtainable by the methods described above:--3 - n - propyloxy, 3-isopropyloxy, 3-n-butoxy, 3 : 6-dimethoxy, 3-methoxy - 5 - methyl, 3-methoxy - 6 - methyl, 3 - methoxy - 2<1> - methyl (A), 3 - methoxy - 2<1> - chloro, 3 - methoxy - 2<1> : 5<1> - dimethyl (B), 3-methoxy-2<1>-methyl-5<1>-chloro, 3-methoxy-2<1> : 5<1>-dichloro; 3 : 6-dimethyl, 3-methyl-3<1>-chloro (C), 3-benzyloxy, 3 : 2<1>-dimethyl-6 : 5<1>-dichloro, 3 : 6-diethoxy, and 3-cyclohexyloxy.  Acetyl derivatives of the compounds A, B and C are also described.  This subject-matter does not appear in the Specification as accepted.