Process for the preparation of 1-benzoylamino-8-hydroxynaphthalene-4,6-disulphonic acid (benzoyl-K acid)

摘要

The invention relates to a process for the preparation of 1-benzoylamino-8-hydroxynaphthalene-4,6-disulphonic acid (benzoyl-K acid) by reacting 1-amino-8-hydroxynaphthalene-4,6-disulphonic acid (K acid) with benzoylating agents, according to which process mixtures of aminonaphtholdisulphonic acid isomers are used instead of pure K acid, which mixtures contain over 40% by weight of K acid, relative to the total amount of diazotizable compounds in the mixture of isomers, and in which no other single isomer has a proportion which exceeds 10% by weight of the total amount of diazotizable compounds in the mixture of isomers.