Process for the preparation of benzothioxanthene dyestuffs

US5280128A · kind A · utility

Assignee

• Cassella Aktiengesellschaft · DE

Inventors

• Wolfgang Bauer · Krefeld, DE
• Eberhard Grimm · Ingolstadt, DE
• Uwe Nickel · Bad Homburg vor der Höhe, DE
• Manfred Schrod · Weiterstadt, DE
• Herbert Wille · Frankfurt, DE

Key dates

• Filing date: Dec 12, 1991
• Grant date: Jan 18, 1994
• Expiry date: Dec 12, 2011

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B57/14
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to a process for the preparation of benzothioxanthene dyestuffs and cyclisation of 3-(2'-aminophenylthio)-benzanathrones wherein the diazotisation and cyclisation are carried out simultaneously in polar, aprotic solvent in the presence of water.