Process for concentrating halogenoanthraquinones

US4162946A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Bernd Thelen · Leverkusen, DE
• Norbert Majer · Odenthal, DE
• Reinold Schmitz · Blecher, DE
• Hans-Samuel Bien

Key dates

• Filing date: Sep 1, 1977
• Grant date: Jul 31, 1979
• Expiry date: Sep 1, 1997

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B01D3/148
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

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 Advantageously, distillation is carried out continuously in a cascade of columns, the products withdrawn from the top of the first column being 2-chloroanthraquinone in the first stage, 1-chloroanthraquinone in the second stage, 1,6- and 1,7-dichloroanthraquinone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, c…