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:
Jan. 11, 1977
Filed:
Sep. 19, 1975
Andreas Huppertz, Cologne-Mulheim, DT;
Peter Schultz, Leverkusen, DT;
Dieter Maertens, Schildgen, DT;
Bayer Aktiengesellschaft, Leverkusen, DT;
Abstract
The invention relates to a process for the preparation of 1,5-dihydroxyanthraquinone and 1,8-dihydroxy-anthraquinone and of their mixtures. Alkali metal salts or alkaline earth metal salts of the corresponding anthraquinonedisulphonic acid are treated, in an aqueous medium under pressure and at elevated temperatures, with lime, buffer substances and, if appropriate, oxidizing agents, a surface-active agent is added to the resulting reaction mixture and the mixture is then acidified in a continuous process with mineral acid at temperatures of 50.degree. C to 150.degree. C and a pressure of 1-3 bars, and the dihydroxyanthraquinone which has precipitated is isolated. Compared to the known procedure, the process according to the invention is distinguished by a substantially improved space-time yield with at least equal purity of the reaction products.