Phosphorus trichloride → n-Butyl tert-butyl chlorophosphine

To a solution of phosphorus trichloride (55 g) in dry diethyl ether (200 cm3) stirred and maintained at between -25° C. and -30° C. in an atmosphere of dry nitrogen a 2 molar solution of tert-butyl magnesium chloride in diethyl ether (200 cm3, solution supplied by Aldrich Chemical Co.) was added during 45 min. After a further 30 min., a 2 molar solution of n-butyl magnesium chloride (200 cm3, solution supplied by Aldrich Chemical Co.) was added in the same way. The suspension was stirred at -25° C. for a further 45 min., then allowed to reach ambient temperature, and finally boiled under reflux for 30 min., cooled, filtered to remove magnesium chloride, and distilled, yielding n-butyl tert-butyl chlorophosphine (30.8 g), b.p. 76°-78° C. under a pressure of 15 mm of mercury.