New approaches to PF compounds. Amine-HF-adducts as fluorinating agents in phosphorus chemistry

Abstract

Amine-HF adducts are excellent fluorinating agents, Their reaction with P(III)-compounds, PX 3 (X = OR, NR 2, halogen), gives HPF 5 − in high yield, From this product PF 3 can be generated in a convenient way, [1] . Organylchlorophosphanes, RPCl 2, react with Et 3N·n HF yielding RPF 2, RPHF 4 −, RPF 5 − and (RP) n, resp., in dependence on the amine/HF ratio. The reaction of Et 3N·n HF with PCl 5 results in the formation of hexafluorophosphate, PF 6 −. In the presence of sec, amines, however, PF 5-amine adducts, PF 5·HNR 2, are obtained. These adducts react with alcohols forming (RO)PF 5 −, [2]. Combined with CCl 4 organylammonium fluorides are useful agents for oxidative fluorination of tervalent phosphorus compounds. Thus, (RO)PF 5 −, (RO) 2P(O)F, (Et 2N) 2P(O)F, (Et 2N) 2(EtO)PF 2, (Et 2N) 3PF 2 and [(Et 2N) 3PF] + are obtained from P(OR) 3, P(OEt) (NEt 2) 2 and P(NEt 2) 3, resp.. In the system CCl 4/Et 3N·n HF/sec. amine even elemental phosphorus, P 4, is oxidized yielding HPF 5 −, R 2NH.PF 5 and (R 2N) 2P(O)F. If alcohols are added to this system (RO)PF 5 −, (RO) 3PO and (R 2N) 2P(O)F are the reaction products, [3].