Photophysical properties and photochemical activity of 6-X-5-nitroquinoxalines with electrondonor substituents (X = H, CH3, Cl, OC2H5, NH2) ortho to the nitro group were studied. The quantum yield of the formation of 5-hydroxyquinoxaline from the corresponding nitro derivative depends on the nature of the substituent and irradiation conditions. Phototransformations can go through nitro-nitrite rearrangement with the participation of two alternative T(pipi*) levels, depending on the size and electronic effects of the substituent. The latter factor is largely determined by the population on excitation of different charge-transfer states involving the nitro group.
Photophysical properties and photochemical activity of 6-X-5-nitroquinoxalines with electrondonor substituents (X = H, CH3, Cl, OC2H5, NH2) ortho to the nitro group were studied. The quantum yield of the formation of 5-hydroxyquinoxaline from the corresponding nitro derivative depends on the nature of the substituent and irradiation conditions. Phototransformations can go through nitro-nitrite rearrangement with the participation of two alternative T(pipi*) levels, depending on the size and electronic effects of the substituent. The latter factor is largely determined by the population on excitation of different charge-transfer states involving the nitro group.
Photophysical properties and photochemical activity of 6-X-5-nitroquinoxalines with electrondonor substituents (X = H, CH3, Cl, OC2H5, NH2) ortho to the nitro group were studied. The quantum yield of the formation of 5-hydroxyquinoxaline from the corresponding nitro derivative depends on the nature of the substituent and irradiation conditions. Phototransformations can go through nitro-nitrite rearrangement with the participation of two alternative T(pipi*) levels, depending on the size and electronic effects of the substituent. The latter factor is largely determined by the population on excitation of different charge-transfer states involving the nitro group.