The photochemistry of several methyl-substituted p-methoxy-β-phenylpropiophenones (1-5) has been examined by nanosecond laser flash photolysis using 337-nm laser excitation. The ketone triplets decay by intramolecular β-aryl quenching of the carbonyl in a well-known process that is believed to involve charge transfer. Surprisingly, methyl substitution at the β- methylene group, which is not a participant in the deactiviation mechanism, causes a ...
