Decay kinetics of benzophenone oxide in the liquid phase

The kinetics of self-termination of benzophenone oxide (BPO) in the liquid phase was studied by flash photolysis. The extinction coefficient of BPO (ε) was found to be virtually independent of the solvent nature, ε=(1.9±0.1)·10³ L mol⁻¹ cm⁻¹. The rate constant of the BPO self-temination increases from 1.8·10⁷ (MeCN) and 7.4·10⁷ (C₆H₆) to 1.5·10⁹ (n-decane) and 2.0·10⁹ 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 great contribution is made by the biradical structure resulting in an increase in the rate constant and a shift of the absorption maximum to the long-wave region (from 410 nm in MeCN to 425 nm inn-pentane). In solutions of benzene and acetonitrile, benzophenone oxide reacts with the parent diazo compound with a rate constant of (2–4)·10⁵ L mol⁻¹ s⁻¹ (293±2 K) along with the self-termination. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1329–1332, July, 1998.