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:
Apr. 11, 1989
Filed:
Sep. 17, 1986
Applicant:
Inventors:
Richard B Lund, Jackson, AL (US);
Glenn W Brown, Wagarville, AL (US);
Assignee:
Ciba-Geigy Corporation, Ardsley, NY (US);
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
C07C / ;
U.S. Cl.
CPC ...
260510 ;
Abstract
A process for preparing bis-diaminostilbene dilsulfonic acid from bis-dinitrostilbene disulfonic acid by an improved Bechamp reduction process is disclosed. The process involves reduction with metallic iron in an acidic medium consisting of 0.033 to 0.27% of acetic acid and 0.38 to 0.76% of sulfuric acid in water at an oxidation-reduction potential (iron/thalamide electrode) in the range 140 to 270 millivolts.