Organophosphorus chemistry. Part X. Reaction of dimethyl- and bis(trifluoromethyl)-phosphines with trifluoroethylene

Abstract

Dimethyl- and bis(trifluoromethyl)-phosphines react smoothly with trifluoroethylene under u.v. irradiation to give good yields of 1 : 1 addition products. Bis(trifluoromethyl)phosphine gives almost exclusively 1,2,2-trifluoro-ethylbis(trifluoromethyl) phosphine, as expected on the basis of the stabilities of the two possible intermediate free radicals. Dimethylphosphine gives dimethyl-1,2,2-trifluoroethylphosphine, expected on the basis of intermediate radical stability, and an almost equal amount of the 1,1,2-trifluoroethyl isomer. The proportion of attack on the CF₂ group of trifluoroethylene is thus higher for Me₂P than that for any radical previously reported. The product distribution for the series of radicals Me₂P, H₂P, (CF₃)₂P is related to the electronic effects of the groups attached to phosphorus.