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:
Dec. 24, 1991
Filed:
Apr. 15, 1991
Applicant:
Inventors:
Reinhold Kohlhaupt, Frankenthal, DE;
Manfred Gaeng, Bobenheim-Roxheim, DE;
Lothar Haas, Dannstadt-Schauernheim, DE;
Guenter Engelhardt, Mannheim, DE;
Walter Bieg, Gruenstadt, DE;
Matthias Fankhaenel, Mannheim, DE;
Assignee:
BASF Aktiengesellschaft, Ludwigshafen, DE;
Primary Examiner:
Int. Cl.
CPC ...
C07D / ;
U.S. Cl.
CPC ...
548457 ;
Abstract
A process for the preparation of purified indigo comprises extracting the aqueous alkaline indoxylate solution arising from the synthesis with an inert water-insoluble solvent in the absence of oxygen before oxidizing the indoxylate solution to give indigo.