Process for the preparation of vinylphosphonic dichloride

摘要

The invention relates to a process for the preparation of vinylphosphonic dichloride, in which a 2-chloroethanephosphonate of the formula <IMAGE> <IMAGE> or a mixture of the two esters, is reacted with thionyl chloride at a temperature of 60 DEG to 160 DEG C. in the presence of a catalyst which contains tertiary phosphines, quaternary ammonium or phosphonium salts or alkali metal or alkaline-earth metal halides. During this reaction, any thionyl chloride which may be present is removed by distillation subsequent to this reaction, the mixture remaining is heated to 140 DEG to 200 DEG C., and the vinylphosphonic dichloride produced during this is removed by distillation.