Photodissociation of 1,2,3-triazine

Abstract

The photolysis of 1,2,3-triazine in hexane and methanol solvents and in the vapour phase has been studied at a number of wavelengths in the main absorption band. For solutions of the triazine in hexane, two forms have been spectroscopically identified. They correspond to hydrogen-bonded, owing to the presence of trace quantities of water, and non-bonded species, In methanol solutions, such spectroscopic resolution was not achieved. Photodissociation quantum yields were found to decrease with increasing wavelength. For photolysis of hexane solutions conducted at the shorter wavelengths, the quantum yields were larger for the hydrogen-bonded species. The quantum yields were independent of solvent, the presence of air and the incident light intensity. The identification of acetylene and the observation of an unidentified photoproduct(s) suggest that the concerted photofragmentation mechanism cannot be the one and only photodecomposition pathway in hexane and methanol solutions. However, for the vapour the identification of acetylene and HCN suggest that it may be the mechanism.