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

US4178308A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

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

Key dates

• Filing date: Jun 28, 1978
• Grant date: Dec 11, 1979
• Expiry date: Jun 28, 1998

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C22B34/12
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A process has been invented for the preparation of a mono-alkali metal salt 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 at elevated pressure and elevated temperature and in the presence of an alcohol or alcoholate, and separating out the mono-alkali metal salt by acidification. The process results in the procurement of higher yields of the desired product and in the formation of less by-products.