in further solvent(s) dissolving PCl3 distd. under N2 in benzyl chloride distd. under N2; addn. of NH4Cl dryed in vac. and passing in the corresponding amount of Cl2; heating in a stream of N2 at 130 °C; removal of formed HCl by a stream of N2;; filtration, distg. off the solvent at 40 °C and 0.5 Torr; recrystn. from petroleum ether; product contains small amounts of higher polymers;;