Dynamit Nobel Aktiengesellschaft

Gunter Meyer

Moustafa El-Chahawi

Kurt Huhn

Dirk Glembin

Manfred Thallmeier

From reaction solutions of carboxylic acids prepared by carbonylation with the aid of cobalt carbonyl catalysts, the cobalt of the catalyst is precipitated by the addition of at least equivalent amounts of monocarboxylic or dicarboxylic acids and neutralization with alkaline agents, in the form of a cobalt(II) salt of the added acid, and the carboxylic acid is completely recovered from the reaction solution by acidification.

Method of preparing pure carboxylic acids

In a method for the removal of alkali halides by washing them out of reaction products prepared, in the presence of ketones which form a miscibility gap with water, by a reaction of xylylene dichlorides and/or bromides with bisphenols in the presence of alkaline compounds or in the form of alkali salts, at 85.degree. to 160.degree. C., with the addition in some cases of terminal-group-closing monophenols or monohalogen alkyl compounds, water or a water-ketone mixture solvent is added to the reaction mixture before beginning the filtration, and afterward is recycled. For the complete recovery of the ketones and alkali halides and the reuse of the ketones with reduced energy consumption a kentonous phase and an aqueous phase are recovered by separate evaporation after the separation of the filtrate in two liquid phases, both of the condensates are combined to a ketone-water mixture, the filter cake is stirred up again in the ketone-water mixture and filtered a second time.

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Troisdorf-Sieglar, Germany

Gunter Meyer