Photocyclization reaction of some 2-methyl-4-phenyl- substituted aldehyde thiosemicarbazones. Mechanistic aspects

Irradiation of 2-methyl-4-phenyl- substituted benzaldehyde thiosemicarbazon es led with good yields to the corresponding Delta(2-)1,2,4-triazoline-5-th ione derivatives through the formation of st;stable 1,2,4-triazolidine 5-th ione intermediates. The relative quantum yields of photocyclization at 313 nm were analysed by means of the Hammett equation and rho values determined . We interpreted the results in terms of the mechanism of photocyclization of 2-methyl-4-phenyl-substituted benzaldehyde thiosemicarbazones. (C) 2000 Elsevier Science Ltd. All rights reserved.