AbstractPhotochemical oxetane formation by addition of 1‐methyl‐2,4,5‐triphenylimidazole (1a), 1,2‐dimethyl‐4,5‐diphenylimidazole (1b), and 1‐acetylimidazole (1c) to benzophenone (BP), poly(4‐vinylbenzophenone) (PVBP), and poly(styrene‐co‐4‐vinylbenzophenone) (PSVBP) was studied in the solution and solid phases. In solution, BP underwent the photoaddition smoothly to all three imidazoles1a–1c. On the other hand, the photoaddition of PVBP and PSVBP depended on the imidazole employed, that is,1band1cproduced the corresponding oxetane, but1adid not. The lack of oxetane formation from the polymeric BP and1ais probably due to a rapid triplet‐sensitized decomposition of a once‐formed oxetane ring as a result of the intramolecular triplet energy transfer from a pendant benzophenone group.
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