Process for the preparation of new crystal modification of an azo dyestuff

US4921505A · kind A · utility

Assignee

• Cassella Aktiengesellschaft · DE

Inventors

• Gunther Effenberger · Bad Vilbel, DE
• Hubert Kruse · Kelkheim, DE

Key dates

• Filing date: Dec 12, 1988
• Grant date: May 1, 1990
• Expiry date: Dec 12, 2008

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S8/924
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

In the process for the preparation of the dyestuff of the formula I ##STR1## by diazotization and coupling, the aqueous suspension present when the coupling has ended is heated to temperatures of 50.degree. C. up to the boiling point of the aqueous phase in the presence of a dispersing agent.