Process for the regiospecific sulfonation of sulfonyl substituted

Abstract

A process for the preparation of isomerically pure sulfonic acids of 2-aminonaphthalenes having a fiber reactive substituent of the formula --(SO.sub.2 X) wherein X is --CH.sub.2 --CH.sub.2 --Z and Z is a substituent such as thiosulfato, phosphato or sulfato. The process comprises a first step of acylating the amino group of the substituted 2-aminonaphthalene to form a N-acyl derivative of the formula, R--CO--NH--A--SO.sub.2 X wherein A represents a naphthalene nucleus. The N-acyl derivative is then sulfonated to provide an essentially isomerically pure sulfonic acid derivative of the formula R--CO--NH--A(--SO.sub.2 X, --SO.sub.3 H). Depending upon the position of the --SO.sub.2 X group in the starting material, the sulfonation reaction product will have one of the following isomeric ring positions for the sulfonyl and sulfo groups, respectively; 5:7 or 7:5 or 6:8 or 8:6. Exemplary products are 2-acetylamino-5-(beta-sulfatoethylsulfonyl)-naphthalene-7-sulfonic acid or 2-acetylamino-7-(beta-sulfatoethylsulfonyl)-naphthalene-5-sulfonic acid or 2-acetylamino-6-(beta-sulfatoethylsulfonyl)-naphthalene-8-sulfonic acid or 2-acetylamino-8-(beta-sulfatoethylsulfonyl)-naphthalene-6-sulfonic acid. The latter aminonaphthalene sulfonic acid having 2-8-6 substitution is an important starting material for the preparation of fiber reactive dyes; the former three are not. New monoazo and disazo dyes or their metal complexes may be prepared from the 2,6,8; 2,5,7; and 2,7,5 isomers by diacylating, diazotizing and coupling them with coupling components selected from an unsubstituted or substituted benzene, naphthylene, acetoacetic acid arylide, arylamide, pyazolone or pyridone.