Process for preparing acylphosphanes and their oxides and sulphides

Abstract

A process for the preparation of bis-acylphosphanes of formula RP(COR)wherein Ris unsubstituted phenyl or phenyl substituted by one to five halogen, C-C-alkyl, C-C-alkylthio and/or C-C-alkoxy; Ris C-C-alkyl or C-C-alkenyl; C-C-alkyl or C-C-alkenyl substituted once or more than once by halogen —OR, —OCO—R, —OCO-Hal, —COO—R, —N(R)—CO—R, —N(R)—CO-Hal, —CO—NRR, —CH═CH—CO—ORor —CH═CH-phenyl; —C(C-Calkyl)=C(C-Calkyl)-CO—ORor —C(C-Calkyl)=C(C-Calkyl)-phenyl; C-Ccycloalkyl, C-Calkenyl, phenyl-C-Calkenyl, phenyl, naphthyl, biphenyl or a 5- or 6-membered —O—, S— or N-containing heterocyclic ring, the radicals phenyl, naphthyl, biphenyl or the 5- or 6-membered -0-, S— or N-containing heterocyclic ring being unsubstituted or substituted by one to five halogen, C-Calkyl, C-Calkoxy and/or C-Calkylthio; the process comprises the steps in a) selective reduction of dichlorophenylphosphanes of the formula RP(CI)by means of hydrogen at a temperature in the range from 20 to 200° C. and under hydrogen pressure of atmospheric pressure to 20 bar in the presence of a hydrogenation catalyst, a tert. aliphatic amine or an aromatic amine and in the presence of a non protic solvent which is unreactive under the hydrogenation conditions to obtain cyclic phenylphosphanes (RP)(n=4 to 6); or b) selective reduction of RP(CI)by means of hydrogen at a temperature in the range from 80 to 250° C. and under hydrogen pressure of 25 to 250 bar in the presence of a hydrogenation catalyst, a tert. aliphatic amine or an aromatic amine and in the presence of a non protic solvent which is unreactive under the hydrogenation conditions to obtain RPH; c) subsequent reaction with an acid halide of formula in the presence of an apropriate base RCOHal wherein Ris as defined above.