GB671762A - Manufacture of new cupriferous azodyestuffs of the stilbene series - Google Patents

Abstract

2 - (31 - Amino - 41 - hydroxy - phenyl)-benzimidazole is obtained by condensing o-phenylene diamine with 3-nitro-4-hydroxy-benzoyl chloride to give 2-(31nitro-41-hydroxy-phenyl)-benzimidazole and reducing the nitro group, e.g. catalytically with nickel.ALSO:The invention comprises dyestuffs of the formula <FORM:0671762/IV (c)/1> where X is hydrogen or methoxy, Z is azo or azoxy, Y is nitro or R1-N=N-R2-Z-, R1 is the residue of a diazo component and R2 is a benzene residue with Z para to -N=N-; R1-N=N-R2 may be present in the form <FORM:0671762/IV (c)/2> These are made by coupling diazotized 2-(31-amino - 41 - hydroxy - phenyl) - benzimidazole in acid medium with 3-methoxyaniline or 2 : 5-dimethoxyaniline; the resulting monoazo dyestuff is condensed with 4 : 41-dinitrostilbene-2 : 21-disulphonic acid in equimolar proportions and the product coppered under demethylating conditions, e.g. heating with a cuprammine complex or by the process of Specification 644,883. The resulting dyestuff has Y=nitro, and if the group R1-N=N-R2-Z- is to be introduced, the condensation with the dinitrostilbene-disulphonic acid is effected in the presence of a further mol. of an amino-azo-dyestuff R1-N=N-R2-NH2 which may or may not be the same as the other reactant, giving a symmetrical or unsymmetrical product respectively. If desired, less than 1 mol. of the second aminoazo dyestuff is used, in which case the product is a mixture. The group Z may be azo or azoxy, or if two groups Z are present in the final product, one may be azo and the other azoxy. The cupriferous dyestuffs give wash- and light-fast yellow-brown to olive shades on wool, leather, linen, cotton, artificial silk or staple fibres of regenerated cellulose. They may be applied by dyeing or printing. Examples show the preparation of (1) the symmetrical dyestuff (X=H) and (2) the unsymmetrical dyestuff (X=H) using as the second component the monoazo dyestuff 2-naphthylamine-4 : 8-disulphonic acid-->amino - p - xylene, -->m-toluidine or -->2-methoxyaniline. A further example shows the dyeing of cotton with the product of (1).