Hoechst Aktiengesellschaft

Johannes Rosenthal

Klaus Gehrmann

Alexander Ohorodnik

Eberhard Auer

Stefan Schafer

The disclosure relates to a process for the continuous production of 2-carboxyethyl-alkyl-phosphinic acid dialkylesters by reacting an alkanephosphonous acid monoalkylester with an acrylic acid ester in the presence of a metal alcoholate. To this end, the disclosure provides:

Process for the continuous production of 2-carboxyethyl-alkyl-phosphinic

The disclosure relates to an improved process for making alkanephosphonous acid esters which comprises: introducing a stoichiometric excess each of an alkyldihalogenophosphane and aliphatic alcohol into a reaction column and reacting them therein at a temperature higher than the boiling point of the reactants but lower than the boiling point of the resulting alkanephosphonous acid ester, this latter being obtained in the base portion of the reaction column and being removed therefrom; continuously expelling overhead of the reaction column a vaporous mixture consisting of by-products formed during the reaction, in the form of hydrogen halide and halide of the aliphatic alcohol, together with aliphatic alcohol in excess, and separating the mixture into its components in a series-connected distilling column, the aliphatic alcohol obtained in the base portion of the distilling column being removed therefrom and recycled into the reaction column, and selectively condensing the mixture issuing overhead with recovery of hydrogen halide gas and liquefied halide of the aliphatic alcohol.

Process for making alkanephosphonous acid esters

The disclosure relates to a process for making methyldichlorophosphane by reacting methane with phosphorus trichloride in the presence of 2 to 7 mol % carbon tetrachloride, based on the phosphorus trichloride used, at temperatures of 500.degree. to 650.degree. C. and over a period of time of 0.1 to 0.9 second. More particularly, the reaction is effected under a pressure of 2 to 10 bars, the proportion of carbon tetrachloride added being reduced at increasing pressure.

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Cologne, Germany

Johannes Rosenthal