Acyclic asymmetrical monoacetals of aromatic diketones prodn. - from diketone, alkylating agent and alcoholate, used as photoinitiator

摘要

Prodn. of new acrylic, asymmetrical monoacetals (I) of aromatic diketones (II) of the formulae A'-CO-C(OR')(OR")-A" (I) and A'-CO-CO-A" (II) (where A' and A" are aromatic gps. and R' and R" are ppt. substd. 1-12C hydrocarbyl gps.) involves reacting (II) with an alkylating agent of the formula (R')nX and an alcoholate of the formula (R"O)mMe (in which n and m are 1, 2 or 3, X is a mono- to tri-basic acid gp. and Me is a main gp. I-III metal) in an organic solvent (III). (I) are used as photoinitiators for photocurable compsn., e.g. for the photopolymerisation of olefinically unsatd. monomer (mixts) and the photocure of coating compsns. based on unsatd. polyester resins and compsns. used for photoresists or photopolymer printing plates. Rapid polymerisation or cure occurs, giving scratch-proof coatings with min. discoloration. In an example, benzil methyl benzyl monoacetal was prepd. by reacting benzil with benzyl chloride and NaOMe in dimethylformamide at room temp.