Patent GB-659467-A (GB)
Title: Process for the preparation of azodyestuffs containing the azine ring system
IPC: C09B43/00
Filed: 1949-07-11
Abstract: Azo dyes of the formula <FORM:0659467/IV (c)/1> are treated with acids or acid salts when they are ring-closed to azines, the group R1 being split off; the naphthalene nucleus has at least one sulphonic acid substituent and the aryl group has at least one of the o-positions free; the R-azo- and the -OH groups are oto one another, as also the R1-azo- and -NH aryl groups; R and R1 may contain further azo linkages. The ring-closure may be effected by warming with acids or acid salts or by treatment with concentrated acids at room temperature of below; hydrochloric and sulphuric are suitable acids.  The azine dyes may be converted into metal complexes in the usual way. In the examples: (1) the dyestuff sulphanilic acid --> 2 - anilino - 5 - naphthol - 7 - sulphonic acid (acid coupling) is coupled with diazotized 4-nitro-2-amino-phenol-6-sulphonic acid in the presence of pyridine.  The disazo dyestuff is isolated and ring-closed with hot dilute hydrochloric acid; the azine dyestuff gives brown-red shades on wool becoming violet by after-chroming. The sulphanilic acid may be replaced by its o- and m-isomers or by aniline; (2) the dyestuff aniline-2 : 5-disulphonic acid --> 2 - anilino - 5 - naphthol - 7 - sulphonic acid (acid coupling) is coupled with diazotized 4 : 6-dichlor-2-amino-phenol in the presence of pyridine.  The disazo dyestuff is isolated and ring-closed with sulphuric acid at 40 DEG  C.  The azine dyestuff gives brown shades on wool, grey by after-chroming.  The aniline-2 : 5-disulphonic acid may be replaced by 4-chloraniline-2-sulphonic acid, 1-naphthylamine-4-sulphonic acid or 2-naphthylamine-4 : 8-disulphonic acid.  A similar azine dyestuff is obtained from 2-(41-hydroxy - 31 - carboxy) - phenylamino - 5 - naphthol - 7 - sulphonic acid instead of the 2-anilino-compound; (3) the dyestuff 1-amino-2 - toluene - 4 - sulphonic acid --> 1 - phenylamino - 8 - naphthol - 4 - sulphonic acid (acid coupling) is coupled with diazotized 4-chlor-2-aminophenol and the product ring-closed with sulphuric acid.  The azine dyestuff gives red-brown shades on wool, grey by after-chroming; (4) the dyestuff sulphanilic acid --> 2-phenylamino - 5 - naphthol - 7 - sulphonic acid (acid coupling) is added to the product of coupling 1 mol. of 1-naphthol-3 : 6 : 8-trisulphonic acid with tetrazotized dianisidine.  The trisazo dyestuff is isolated and ring-closed with hydrochloric acid.  The resulting azine dyestuff dyes cellulose green-blue and forms a copper complex.  2 - p - Anisidylamino - 5 - naphthol - 7 - sulphonic acid may similarly be used; (5) the dyestuff 4-aminosalicylic acid --> 1-aminonaphthalene - 7 - sulphonic acid --> 1 - naphthylamine is diazotized and coupled with the dyestuff sulphanilic acid --> 2-phenylamino-5-naphthol-7-sulphonic acid (acid coupling).  The product is ring-closed with sulphuric acid to an azine dyestuff which dyes cellulose reddish-blue-grey suitable for after-coppering; (6) the dyestuff aniline --> 2 - (41 - hydroxy - 31 - carboxy) - phenylamino - 5 - naphthol - 7 - sulphonic acid (acid coupling) is added to the product of coupling 1 mol. of salicylic acid with tetrazotized 4 : 41 - diaminobenzanilide, pyridine being present.  The trisazo dyestuff is isolated and ring-closed with sulphuric acid to give an azine dyestuff which dyes cellulose brown suitable for after-coppering.  Formul  are given of 5 other azine dyestuffs which yield copper complexes.