Process for the preparation of 1-amino-8-naphthol-3,6-disulphonic acid (H-acid)

US4166826A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Willi Schossler · Cologne, DE
• Rolf Putter
• Horst Behre · Odenthal, DE

Key dates

• Filing date: Jun 28, 1978
• Grant date: Sep 4, 1979
• Expiry date: Jun 28, 1998

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C303/22
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process has been invented for the preparation of a mono-alkali metal of 1-amino-8-naphthol-3,6-disulphonic acid, comprising reacting 1-naphthylamine-3,6,8-trisulphonic acid and/or a salt thereof and/or a naphthylamine trisulphonic acid isomer mixture and/or salt thereof with an alkali metal hydroxide solution in the presence of an alcohol and/or alcoholate and in the presence of a substance which contains at least one oxygen atom bonded to a nitrogen atom, at elevated pressure and elevated temperature, and separating out the mono-alkali metal salt of 1-amino-8-naphthol-3,6-disulphonic acid by acidification. The process results in the procurement of higher yields of the desired product and in the formation of less by-products.