The photoreactions of N-methyl-2-pyridone

In studying the photochemistry of N-methyl-2- pyridone, four products were observed. Besides the previously known dimer and bicyclic monomer, two new dimers were isolated. The quantum yields of product formation were measured, and it was found that only one intermediate was involved. From sensitization and quenching experiments, the lowest excited singlet state appears to be that intermediate although a highly reactive, ground state isomer cannot be ruled out. Some spectroscopic evidence for this isomer is given.