Hoechst Aktiengesellschaft

By Mark Haberlein, Heir

Frank Ebmeyer

Harald Haberlein, Deceased

By Jorg Haberlein, Heir

By Hans Haberlein, Heir

Holger Mohn

The present invention relates to a process for preparing a particularly pure glycolic acid by saponification with chloroacetic acid with an excess of alkali metal hydroxide, with the resulting alkali metal chloride being filtered off, and the 20 to 70% strength by weight glycolic acid solution being subsequently subjected to an electrodialysis at 20.degree. to 40.degree. C. and a cell voltage of 0.5 to 2.5 V per cell pair. The process of the invention permits optimum removal of sodium chloride and chloroacetic acid as necessary for preparing a particularly pure glycolic acid. Other organic acids, nitrogen compounds, aldehydes and salts are not produced in this process and thus do not affect the product quality.

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Freiburg, Germany

By Mark Haberlein, Heir