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

US4325889A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Horst Behre · Odenthal, DE
• Albert Hullen · Langenfeld, DE
• Bruno Kruger · Leverkusen, DE
• Guido Steffan · Odenthal, DE

Key dates

• Filing date: Sep 12, 1980
• Grant date: Apr 20, 1982
• Expiry date: Sep 12, 2000

Classification

• Technology area (CPC —): General

Abstract

The invention relates to a process for the preparation of 1-amino-8-naphthol-3,6-disulphonic acid (H-acid) as the mono-alkali metal salt from napthylamine-trisulphonic acid isomer mixtures by alkaline hydrolysis under pressure. The separation of the H-acid is effected by utilizing an aqueous sulphuric acid which contains naphthalene- and/or nitronaphthalene- and/or naphthylamine- and/or naphthol- and/or aminonaphthol-mono-, -di-and/or-tri-sulphonic acids.