PHOTODISSOCIATION OF 1,2,3-TRIAZINE

The photolysis of 1,2,3-triazine in hexane and methanol solvents and i n the vapour phase has been studied at a number of wavelengths in the main absorption band. For solutions of the triazine in hexane, two for ms have been spectroscopically identified. They correspond to hydrogen -bonded, owing to the presence of trace quantities of water, and non-b onded species. In methanol solutions, such spectroscopic resolution wa s not achieved. Photodissociation quantum yields were found to decreas e with increasing wavelength. For photolysis of hexane solutions condu cted at the shorter wavelengths, the quantum yields were larger for th e hydrogen-bonded species. The quantum yields were independent of solv ent, the presence of air and the incident light intensity. The identif ication of acetylene and the observation of an unidentified photoprodu ct(s) suggest that the concerted photofragmentation mechanism cannot b e the one and only photodecomposition pathway in hexane and methanol s olutions. However, for the vapour the identification of acetylene and HCN suggest that it may be the mechanism.