Patent GB-851903-A (GB)
Title: Process for the production of diazo-azo compounds containing sulphonic acid groups
IPC: C07C245/08
Filed: 1958-04-15
Abstract: Diazo-azo compounds containing sulphonic acid groups are prepared by reacting aromatic hydrazines having in o- and/or p-position to the hydrazino group a sulphonic acid group, or heterocyclic hydrazines having a sulphonic acid group on the carbon atom adjacent the carbon atom having the hydrazino group, with nitrophenols or their acyl derivative and, after cleavage of the acyl radical where an acyl derivative has been used, the hydroxylamino-azo compounds thus formed are converted in aqueous mineral acid solution by the action of two molar proportions of a nitrite used for diazotisation to give the corresponding diazo-azo compounds.  Specified hydrazines are phenylhydrazine-2-or-4-sulphonic acid, phenylhydrazine-2:4- or -2:5-disulphonic acid, 5-chloro-or 4-methyl- or 4-nitrophenylhydrazine-2-sulphonic acid, 2-nitrophenylhydrazine-4-sulphonic acid, 2-naphthylhydrazine-3:6-disulphonic acid, 4:41-dihydrazinodiphenyl-3:31-disulphonic acid and 2-(41-hydrazino-31sulphophenyl) -6-methyl-7-sulphobenzthiazole. Specified nitrophenols are 4-nitrophenol,3-methyl-or -chloro-4-nitrophenol, 2-methyl- or -chloro- or -sulpho-4-nitrophenol and their acyl derivatives e.g. acetyl or benzoyl.  In Examples : (1) phenylhydrazine-2-sulphonic acid and p-nitrosophenol are reacted in aqueous sulphuric acid, the reddish-violet crystalline product is filtered off and treated with sodium nitrite in aqueous sulphuric acid to give the compound of formula :  <FORM:0851903/IV(b)/1> (2) phenylhydrazine-4-sulphonic acid is reacted with acetylated p-nitrophenol in ethanol, the crystalline reaction product saponified with aqueous sulphuric acid and the resultant mixture treated with sodium nitrite to give a product which is identical with that obtainable by diazotising 4-aminoazobenzene-41-sulphonic acid. Further examples are given.ALSO:Diazo-azo compounds containing sulphonic acid groups are prepared by reacting aromatic hydrazines having in o- and/or p-position to the hydrazino group a sulphonic acid group or heterocyclic hydrazines having a sulphonic acid group on the carbon atom adjacent the carbon atom having the hydrazino group, with nitrophenols or their acyl derivatives and, after cleavage of the acyl radical where an acyl derivative has been used, the hydroxylamino-azo compounds thus formed are converted in aqueous mineral acid solution by the action of two molar proportions of a nitrite used for diazotisation, to give the corresponding diazo-azo compounds.  Specified hydrazines are phenylhydrazine -2- or -4- sulphonic acid, phenylhydrazine -2 : 4- or -2 : 5- disulphonic acid, 5- chloro- or 4-methyl- or -nitro-phenylhydrazine -2- sulphonic acid, 2- nitrophenyl-hydrazine -4- sulphonic acid, 2-naphthylhydrazine -3 : 6- disulphonic acid, 4 : 41- dihydrazinodiphenyl -3 : 31- di-sulphonic acid and 2-(41-hydrazino-31-sulphophenyl)-6-methyl -7- sulphobenzthiazole.  Specified nitrosophenols are 4- nitrosophenol, 3- methyl- or-chloro -4- nitrosophenol, 2- methyl- or -chloroor -sulpho -4- nitrosophenol and their acyl derivatives, e.g. acetyl or benzoyl.  In examples (1) phenylhydrazine -2- sulphonic acid and p-nitrosophenol are reacted in aqueous sulphuric acid, the reddish violet crystalline product is filtered and treated with sodium nitrite in aqueous sulphuric acid to give the compound of formula: <FORM:0851903/IV (c)/1> (2) phenylhydrazine -4- sulphonic acid is reacted with acetylated pnitrosophenol in ethanol, the crystalline reaction product saponified with aqueous sulphuric acid and the resultant mixture treated with sodium nitrite to give a product which is identical with that obtainable by diazotising 4- aminoazobenzene -41- sulphonic acid.  Further examples are given.