A laser flash photolysis study on the reaction mechanisms of benzil with various amines

Laser flash photolysis of benzil in the presence of various amines was inve stigated to determine absolute reaction quantum yield (phi(r),) of benzil k etyl radicals produced from both free tripler benzil and ground state compl ex. The reaction quantum yields of benzil ketyl radical from free triplet b enzil (phi(r)(free)) were 0.31, 0.17, 0.13, 0.08, and ca. 0 for triethylami ne (TEA), N,N-diethylaniline, diethylamine, N-ethylaniline, and aniline, re spectively. phi(r)(free) largely depends on the number of the hydrogen atom s that can be abstracted by benzil. The reaction quantum yield of the compl ex formed in the ground state (phi(r)(com)) was determined to be unity for all amines used. This large quantum yield (phi(r)(com) = 1) was explained b y a calculated conformation of the ground state complex.