GB695758A - Process for the preparation of disazo dyestuffs - Google Patents

Abstract

The invention comprises disazo dyestuffs of the formula <FORM:0695758/IV (c)/1> where R is a p-coupling salicylic acid residue. The invention also includes a process of making disazo dyestuffs by coupling diazotized amino-azo compounds of the formula <FORM:0695758/IV (c)/2> with amino derivatives of 1-naphthol-3-sulphonic acid (which may contain a further sulphonic acid group), the amino groups being acylated before or after coupling. The monoazo intermediates are p made by coupling diazotized p-nitraniline with salicylic acid or a p-coupling derivative thereof, reducing the nitro group to amino, condensing the product with 3-methyl-4-nitrobenzoyl chloride and again reducing the product. The disazo dyestuffs yield red dyeings on cotton and regenerated cellulose which may be after-coppered. When a free amino group is present (e.g. in the acyl residue) the dyestuffs may be diazotized on the fibre and coupled with 2-naphthol to give dischargeable red shades. In the examples, (1) the monoazo compound where R is 3-carboxy-4-hydroxyphenyl is diazotized and coupled with 2-carbethoxyamino-5-naphthol-1 : 7-disulphonic acid; (2) the monoazo compound where R is 3-carboxy-4-hydroxy-5-methylphenyl is diazotized and coupled with N-(p-aminobenzoyl)-g -acid; the product can be diazotized on the fibre and coupled with 2-naphthol; (3) the monoazo compound where R is 3-carboxy-4-hydroxy-6-methylphenyl is diazotized and coupled with J-acid and the product treated with p-nitrobenzoyl chloride; the acylated product may be reduced to the p-aminobenzoyl derivative, diazotized on the fibre and coupled with 2-naphthol. A table is given of other dyestuffs where R is 3-carboxy-4-hydroxyphenyl.