Photochemistry of Polyhaloarenes. 7. Photodechlorination of Pentachlorobenzene in the Presence of Sodium Borohydride

Article abstract of DOI:10.1021/jo00236a030

The mechanism of photodechlorination of pentachlorobenzene (1) in acetonitrile has been examined.The quantum yield of reaction (Φ_r) has been found to vary with the concentration of 1.A charge-transfer intermediate formed from the triplet excited state of 1 is proposed to explain the observations. Φ_r increases with added NaBH4 and 1/Φ_r varies directly with the inverse of the concentration of the electron-transfer reagent.The regiochemistry deuterium isotope effects, tracer studies, and quenching analyses are consistent with an electron-transfer process.