Monoalkylphosphinamides: synthesis and relative stability

Abstract P-Monoalkylphosphinamides [RPH(O)NR′2] have been conveniently prepared by the reaction of the corresponding phosphonous diamides [RP(NR′2)2] with an equivalent of water at ambient temperature. The reaction was in general conducted with an added 10% trimethylamine hydrochloride, which served as an effective catalyst for the hydrolysis. The thermal stability of the phosphinamide products increased in the order MePH(O)NMe2 < MePH(O)NEt2 < EtPH(O)NEt2, with only the latter being stable to vacuum distillation. Thus, the isolated products have all been characterized by their 31P and 1H NMR spectra. The further hydrolysis of N, N-diethylmethylphosphinamide (2b) has been studied and found to be significantly slower than the initial hydrolysis of its precursor, N,N,N′,N′-tetraethylmethylphosphonous diamide (1b).