Basf Aktiengesellschaft

Jochem Henklemann

Thomas Wettling

Bernd Hupfeld

Manfred Dimmler

A multi-stage catalytic process for preparing a 2-(4-hydroxyphenoxy)-propionate, especially methyl 2-(4-hydroxyphenoxy)-propionate, with a purity greater than 99% by esterifying the corresponding 2-(4-hydroxyphenoxy)-propionic acid with an excess amount of alcohol, e.g. methyl alcohol, in a series of at least 2 up to 10 sequential stages at temperatures of 20.degree. to 150.degree. C. and pressures of 0.05 to 5 bar in the presence of a distillable acid catalyst such as hydrochloric acid or hydrogen chloride. In a first esterification stage, unreacted alcohol is removed from the ester product in vacuo at temperatures of 30.degree. to 100.degree. C. together with other volatile components, including the acid catalyst. Without a separate purification of the resulting ester as the bottoms product of the first stage, the esterification step is repeated in at least one additional stage. The final ester product of this multi-stage process is characterized by a water content of less than 0.1%, a halide content of less than 100 ppm, an organic halogen content of less than 50 ppm and a content of all other contaminating compounds of less than 0.1%.

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Mannheim, Germany

Jochem Henklemann