Preparation of anilino azo carbazole dyestuffs prepared by diazotization by nitrosylsulphuric acid in acetic acid

US4472307A · kind A · utility

Assignee

• Cassella Aktiengesellschaft · DE

Inventors

• Ulrich Buhler · Alzenau, DE
• Wolfgang Bodenstedt · Frankfurt am Main, DE
• Heinz Hanel · Oberursel, DE
• Eberhardt Hebestreit · Frankfurt am Main, DE
• Horst Tappe · Dietzenbach, DE

Key dates

• Filing date: Aug 20, 1982
• Grant date: Sep 18, 1984
• Expiry date: Aug 20, 2002

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B41/002
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

An improved process for the preparation of azo dyestuffs of the formula ##STR1## comprising diazotizing a 2-halo-4-nitroaniline at 10.degree. to 35.degree. C. in 70 to 100 percent by weight strength acetic acid by means of nitrosylsulphuric acid, adjusting the acetic acid content of the resulting diazo solution to 60 to 85% by the addition of water, and at a temperature from 15.degree. to 45.degree. C. adding an appropriate carbazole to the diazo solution as a solid or in the form of a suspension in 60 to 100 percent strength by weight acetic acid and coupling the carbazole to the diazotized amine to produce said azo dyestuff and isolating the dyestuff.