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:
Nov. 08, 1988
Filed:
Jan. 22, 1988
Werner Steinbeck, Leverkusen, DE;
Wolfgang Harms, Leverkusen, DE;
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
A process for the preparation of a concentrated storage-stable aqueous solution of the dyestuff of the formula ##STR1## is characterized in that the reaction mixture obtainable from the quinone derivative of the formula ##STR2## by sulphation and subsequent oxidation cyclization, preferably with ammonium, sodium or potassium peroxodisulphate, in oleum is diluted with water or sulphuric acid to a sulphuric acid concentration of 37-50%, preferably 41-43%, and the product which thereby precipitates is separated off and brought to a pH of about 2-6, preferably 3-4, in water with basic lithium compounds, preferably lithium carbonate or lithium hydroxide.