Process for the isolation of 1-naphthylamine-4,6- and 1-naphthylamine-4,7-disulphonic acid

US4348336A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Heinz U. Blank · Odenthal, DE
• Horst Behre · Odenthal, DE
• Hans W. Linden · Leverkusen, DE

Key dates

• Filing date: Mar 25, 1981
• Grant date: Sep 7, 1982
• Expiry date: Mar 25, 2001

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C303/06
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Process for the isolation of 1-naphthylamine-4,6- or 1-naphthylamine-4,7-disulphonic acid from sulphonation mixtures obtained in the sulphonation of 1-naphthylamine-6- or 1-naphthylamine-7-sulphonic acid with sulphuric acid and sulphur trioxide, wherein the aqueous solutions or suspensions formed, when the sulphonation mixtures are introduced into water, are warmed to 80.degree. to 120.degree. C., optionally kept for a period of time at this temperature, are then cooled to temperatures below 70.degree. C., and the 1-naphthylamine-4,6- or 1-naphthylamine-4,7-disulphonic acid which has crystallized out is finally filtered off.