Using 4-methyl-4-phenyl-2-pentanone as a singlet probe of benzene, cyclohexane, tributylphosphate and its multiple scavenger effects

Abstract

A special probe of excited singlet states was established. The Norrish type II elimination reaction of 4-methyl-4-phenyl-2-pentanone (MPP) induced by γ-rays was reinvestigated. By measuring the G value of the sensitization radiolytic product α-methylstyrene (α-MS), we obtained the G value of excited singlet states. It was found that the G value of benzene excited singlets is 1.4±0.2, the rate constant of excitation energy transfer from benzene excited singlets to MPP is (5.2±0.5)×10 9dm 3mol -1 s -1; the G value of excited tributylphosphate singlets is 1.4±0.3, the lifetime of its excited singlets is (1.3±0.1)×10 -7s; the G value of excited cyclohexane singlets is 1.5±0.2, the rate constant of excitation energy transfer from cyclohexane excited singlets to MPP is (4.1±0.4)×10 10dm 3mol -1 s -1. It was found that MPP has multiple effects in quenching the active species formed in the radiolysis of benzene and tributylphosphate, both excitation energy transfer and reaction with subexcitation electrons have occured. A yield of subexcitation electrons of benzene 4.0, that of tributylphosphate 5.0, was obtained. The kinetics of both processes were also discussed.