Reactor-irradiation of phenylphosphorus compounds below 20°K

Abstract

A series of phenylphosphorus compounds were neutron irradiated below 20°K and ³²P-labelled recoil products were analyzed by both solvent extraction and paper chromatography. The identities and yields of recoil products are compared with those produced by dry ice temperature irradiation and by a reactor temperature irradiation. In triphenylphosphine, triphenylphosphine oxide and triphenylphosphate, considerable differences due to the irradiation temperature have been observed. At 20°K, more than 30% of the ³²P has not completed its chemical reactions and has been trapped as intermediates in the crystals. In phenylphosphinic acid and phenylphosphonic acid, however, the irradiation temperature has only little effect on the nature of the products and their yields. It is concluded that P-C bond formation by phosphorus atoms or radicals with phenyl groups mainly occurs in a hot reaction in the high energy region, while the P-OH bond formation occurs in the thermal region as well as in the hot region.