The mechanistic photochemistry of γ-hydroxy-γ-phenylbutyrophenone (1) and its β,γ-dideuterio derivative (2) has been investigated. The presence of a biradical intermediate formed by γ-deuterium abstraction upon photolysis of 2 has been established by the formation of deuterium-hydrogen exchanged ketone 3. A deuterium isotope effect on the rate constant for γ-hydrogen abstraction of 1.7 is observed. A kinetic analysis shows that bond rotations in the biradical are about five times slower than reabstraction of hydrogen or elimination to give acetophenone.
ASJC Scopus subject areas
- Colloid and Surface Chemistry