Synthesis, crystal structures, and laser flash photolysis of tert-butyl aroylperbenzoates

tert-Butyl aroylperbenzoates (1-7) were synthesized. Single-crystal structures for 2 and 5 show that the perester and benzophenone carbonyl groups are almost coplanar in each. Laser flash photolysis (LFP, lambdaex = 355 nm) of 1-5 in CCl4 produces the corresponding aroylphenyl radicals (9-13). The lifetimes of the para aroyl-substituted phenyl radicals (9-12) are similar (approximately 0.4 micros), but each is shorter lived than the meta aroyl-substituted phenyl radical (13). LFP of 2, 6, and 7 also produces different (tert-butyldioxycarbonylbenzoyl)benzyl radicals (8, 14, and 15, lambdamax approximately 320 nm). The lifetimes of each in CCl4 have been found to be approximately 17-18 micros. The effect of substituents on the quantum yield of decomposition of 1-7 and the lifetimes of 9-13 is discussed.