Intramolecular hydrogen bonding of oxidation intermediates of bisphenol derivatives in relation to photothermographic activity in silver salt photothermographic systems

The effects of intramolecular hydrogen bonding on the electron-transfer properties of a series of bisphenol derivatives, as compared with those of monophenol derivatives in which a hydroxy group is replaced with a methoxy group, have been investigated in relation to their photothermographic properties. The oxidation of bisphenol derivatives with one-electron oxidants occurs to give the radical cation, followed by deprotonation, to produce the phenoxyl radical. Both the radical cations and phenoxyl radicals have been detected by laser flash photolysis measurements. Rates of hydrogen-transfer reactions from a series of bisphenol derivatives to cumylperoxyl radicals have been determined by monitoring the decay of the ESR signal caused by the cumylperoxyl radical produced by the photoirradiation of an oxygen-saturated propionitrile solution of cumene and di-t-butylperoxide in the presence of bisphenol derivatives. Intramolecular hydrogen bonding plays an important role in determining overall oxidation reactivity in the two-electron oxidation process by decreasing the one-electron oxidation potentials and also through facilitating the deprotonation step from the bisphenol radical cation in producing a phenoxyl radical.