The reaction of perfluoroalkyl Grignard reagents with phosphorus(III) halides was explored. In the process a new convenient, one-pot, high yield method for the synthesis of (perfluoroalkyl)phosphonic acids has been developed. Perfluoroalkyl Grignard reagents react with phosphorus trichloride or phosphorus tribromide to form (perfluoroalkyl)phosphonous dihalides. Hydrolysis gives the corresponding (perfluoroalkyl)phosphonous acids. Oxidation of the phosphonous acids with H(2)O(2) produces (perfluoroalkyl)phosphonic acids in 60-78% overall yields, based on the corresponding perfluoroalkyl iodide. The X-ray crystal structures of the toluidinium salts, [MeC(6)H(4)NH(3)](2)[C(2)F(5)PO(3)] and [MeC(6)H(4)NH(3)][C(8)F(17)P(O)(2)OH], are reported.

Perfluoroalkyl Grignard reagents react with phosphoryl halides at -78 °C to room temperature to selectively produce bis(perfluoroalkyl)phosphonyl halides, which after aqueous work up, give bis(perfluoroalkyl)phosphinic acids in high overall yields. Reaction of perfluoroalkyl Grignards with phenylphosphonic dichloride gives high yields of bis(perfluoroalkyl)phenyl phosphine oxides which are readily hydrolysed to perfluoroalkyl(phenyl)phosphinic acids.