Manufacture of a 1-amino-2-hydroxynaphthalenesulphonic-3-carboxylic acid, or of a corresponding 2-hydroxynaphthalenesulphonic-3-carboxylic acid

摘要

A 1-amino-2-hydroxynaphthalenesulphonic-3-carboxylic acid is prepared by sulphonating 1 - amino - 2 - hydroxynaphthalene - 3 - carboxylic acid. The corresponding 2-hydroxynaphthalenesulphonic-3-carboxylic acid is obtained by eliminating the amino group from the 1-amino-2-hydroxynaphthalenesulphonic - 3 - carboxylic acid, e.g. by diazotizing it in neutral solution, and heating the separated diazo compound with ethyl alcohol in the presence of copper and copper sulphate. The new compounds are useful as intermediates for dyes.