DECAY KINETICS OF BENZOPHENONE OXIDE IN THE LIQUID-PHASE

The kinetics of self-termination of benzophenone oxide (BPO) in the li quid phase was studied by flash photolysis. The extinction coefficient of BPO (epsilon) was found to be virtually independent of the solvent nature, epsilon = (1.9+/-0.1) . 10(3) L mol(-1) cm(-1). The rate cons tant of the BPO self-termination increases from 1.8 . 10(7) (MeCN) and 7.4 . 10(7) (C6H6) to 1.5 . 10(9) (n-decane) and 2.0 . 10(9) L mol(-1 ) s(-1) (n-pentane) at 293 +/- 2 K. Solvation of BPO promotes a polar state of the molecule in MeCN and C6H6. In nonpolar hydrocarbons, a gr eat contribution is made by the biradical structure resulting in an in crease in the rate constant and a shift of the absorption maximum to t he long-wave region (from 410 nm in MeCN to 425 nm in n-pentane). In s olutions of benzene and acetonitrile, benzophenone oxide reacts with t he parent diazo compound with a rate constant of (2-4) . 10(5) L mol(- 1) s(-1) (293 +/- 2 K) along with the self-termination.