Process for preparing p-toluidine-2-sulphonic acid

US4717514A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Heinz U. Blank · Odenthal, DE
• Herbert Emde · Cologne, DE
• Rolf Schimpf · Leverkusen, DE

Key dates

• Filing date: Apr 4, 1986
• Grant date: Jan 5, 1988
• Expiry date: Apr 4, 2006

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C309/45
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

P-Toluidine-2-sulphonic acid (5-amino-2-methylbenzenesulphonic acid) is obtained in very pure form and virtually free of p-toluidine-3-sulphonic acid (2-amino-5-methylbenzenesulphonic acid) by reacting p-toluidine at 10.degree.-55.degree. C. with oleum in sulphuric acid. The molar ratio of SO.sub.3 to p-toluidine in this reaction is 1-3.0:1. The reaction mixture is worked up by pouring into water and filtering off the precipitated p-toluidine-2-sulphonic acid.