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:
Jul. 31, 1979
Filed:
Sep. 01, 1977
Bernd Thelen, Leverkusen, DE;
Norbert Majer, Schildgen, DE;
Reinold Schmitz, Blecher, DE;
Hans-Samuel Bien, Burscheid, DE;
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
A process for concentrating at least one of (a) individual halogenoanthraquinones (b) binary mixtures of di-halogenoanthraquinones and (c) binary mixtures of trihalogenoanthraquinones, from a mixture containing at least two halogenoanthraquinones, comprising subjecting said mixture containing at least two halogenoanthraquinones to fractional vacuum distillation in a heated rectification column having an efficiency corresponding to about 20 to 50 theoretical stages with an absolute pressure at the top of about 0.5 to 50 mm Hg and a reflux to take-off ratio of about 5/1 to 50/1. Advantageously, distillation is carried out continuously in a cascade of columns, the products withdrawn from the top of the first column being 2-chloroanthraquinone in the first stage, 1-chloroanthraquinone in the second stage, 1,6- and 1,7-dichloroanthraquinone in the third stage and 1,5- and 1,8-dichloroanthraquinone in the fourth stage, 1,4,5- and 1,4,6-trichloroanthraquinone being obtained in the sump of the 4th stage and being separated therefrom by film evaporation. The mixture of halogenoanthraquinones is advantageously a mixture of chloroanthraquinones such as is obtained by the action of chlorine, chloric acid or a chlorate on various industrial mixtures of nitro- or sulfo-anthraquinones.