The reaction of diethyl phosphonate with methyl and ethyl Grignard reagents has been investigated. Chemical and physical evidence suggest that the intermediate (I) $ not a diethoxyphosphmylmagnesium halide [(RO) r P (-. O) MgX] but is a trivalent phosphorus species [(R0) zPOMgXI. The latter undergoes rapid substitution with methyl Grignard reagent at 25" to give the halomagnesium dimethyl-and diethylphosphinites (RsPOMgX), ...
