Process for preparing acylphosphanes and derivatives thereof

Abstract

The invention relates to a process for the preparation of (bis)acylphosphanes of formula I, wherein n and m are each independently of the other 1 or 2; R1 if n=1, is e.g. unsubstituted or substituted C-Calkyl or C-Calkenyl, or phenyl, R1 if n=2, is e.g. a divalent radical of the monovalent radical defined above; R2 is e.g. C-Calkyl, C-Ccycloalkyl, C-Calkenyl, mesityl, phenyl, naphthyl; R3 is one of the radicals defined under R; the process comprises the steps a) contacting e.g. elemental phosphorous [P]∞, P(Hal)with a reducing metal optionally in the presence of a catalyst or an activator in a solvent to obtain metal phosphides MeP or Me'P, wherein Me is an alkali metal and Me′ is an earth alkali metal or to obtain metal polyphosphides b) optionally adding a proton source, optionally in the presence of a catalyst or an activator to obtain metal dihydrogen phosphides MePH; c) subsequent acylation reaction with m acid halides of formula III or m carboxylic acid esters of formula IV or, in case that in formula I m=1, with one carboxylic ester of formula IV followed by one acid halide of formula III or vice versa, wherein R is the residue of an alcohol and Ris as defined above; d) alkylation reaction subsequent reaction with an electrophilic agent RHal or other electrophilic agents to obtain the compounds of formula I. An oxidation step may follow to obtain mono- and bisacylphosphane oxides or mono- and bisacylphosphane sulfides, which are used as photoinitiators.