GB464038A - Manufacture of azo-dyestuffs - Google Patents

Abstract

Azo dyestuffs are manufactured by coupling pyrogallol with 2 or 3 molecular proportions of diazo- or diazoazo-compounds, of which at least one contains a nitro-group, and after-treating the dyestuff thus obtained with a copper salt, of which a very small proportion is generally sufficient. The products dye leather yellow-brown, havana-brown to olive-brown shades. In examples, the following dyestuffs are prepared and treated with a solution of copper sulphate, with or without ammonia: (1) 1-amino-4-nitrobenzene-2-sulphonic acid --> pyrogallol \sM 1 : 3-diamino-4-nitrobenzene; (2) 1-amino-4-nitrobenzene-2-sulphonic acid --> pyrogallol \sM 4<1>-nitro-4-aminodiphenylamine-2<1>-sulphonic acid; (3) 4<1>-nitro-4-aminodiphenylamine-2<1>-sulphonic acid --> pyrogallol \sM 1 : 3-diamino-4-nitrobenzene; the first diazo component may be replaced by 4<1>-methoxy-4-aminodiphenylamine - 2<1> - sulphonic acid; (4) 4 - aminoazobenzene - 4<1> - sulphonic acid --> pyrogallol \sM 1 : 3-diamino-4-nitrobenzene. A sample has been furnished under Sect. 2 (5) of the copper compound of the dyestuffs obtained by coupling pyrogallol with 1 mol-each of the diazo-compounds from 4-aminoazo. benzene - 4<1> - sulphonic acid, 4 - nitro - 1 aminobenzene-2-sulphonic acid and 4-nitro-1-aminobenzene. Specification 415,924 is referred to. The Specification as open to inspection under Sect. 91 comprises also the manufacture of the non-coppered dyestuffs. Reference is made to a sample of the non-coppered dyestuff corresponding to the sample referred to above. This subject-matter does not appear in the Specification as accepted.