The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 18, 1984
Filed:
Aug. 20, 1982
Ulrich Buhler, Schoneck, DE;
Wolfgang Bodenstedt, Frankfurt am Main, DE;
Heinz Hanel, Offenbach, DE;
Eberhardt Hebestreit, Frankfurt am Main, DE;
Horst Tappe, Dietzenbach, DE;
Cassella Aktiengesellschaft, Frankfurt am Main, DE;
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.