On the photolysis of 1-Phenyl-2-hydroxy-2-methyl-propanone-1 in the presence of methylmethacrylate,styrene, and acrylonitrile: Laser flash photolysis studies

1-Phenyl-2-hydroxy-2-methyl-propanone-1 (I) has been irradiated in argonsaturated benzene solution containing various amounts of styrene (St), methyl-methacrylate (MMA) or acrylonitrile (AN) with 25 ns flashes of 347 nm light. The aim of this work was to elucidate the kinetics of (a) the reactions of monomers with the triplets of (I) and (b) the reaction of initiator fragment radicals with monomers. Upon applying the optical absorption detection method the rate constants (in l mol⁻¹ s⁻¹) of the reaction of triplets of I with the three monomers were determined as 7 × 10⁹ (St), 8 × 10⁶ (MMA) and 1 × 10⁷ (AN). Therefore, (I) is not appropriate for photocuring coating formulations on the basis of styrene. Radicals stemming from the α-scission of (I¹) react with the monomers with the following rate constants (in l mol⁻¹ s⁻¹): 4·7 ×10⁵ (St), 6·3 × 10⁵ (MMA) and 1·6 × 10⁶ (AN).