Photoinitiators with Functional Groups. Part II. Silicon-Containing Photoinitiators

The new photoinitiators (PIs) 1-(4-dimethylsilyl)phenyl-2-hydroxy-2-methyl-propan-1-one (8a) and 1-(4-dimethylsilyl)phenyl-2-methoxy-2-methyl-propan-1-one (8b) have been synthesized by Grignard reaction of 4-dimethylsilylphenylmagnesium chloride (5) with protected acetone cyanohydrins. The photoactivity of 8a was similar to the most efficient commercial hydroxyalkylphenone 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 1173) whereas 8b exhibits even higher efficiency. 8a and 8b were reacted with allyl alcohol, allyl amine, vinyl acetic acid, 3-allyloxypropane-1,2-diol, allyl glycidyl ether, polybutadiene, and a vinyl polysiloxane to yield new functional PIs of high activity. Thus, hydrosilation reactions of the new PIs enable the preparation of a variety of functional derivatives usable in different UV-curable systems.