The photolysis of nitrate esters in solution or in thin solid films occurred readily in the 2650 to 3340 A spectral region. In the presence of diphenylamine, phloroglucinol or hydroquinone, the photoreaction yielded colored products that gave a measure of the extent of the reaction. The most effective wavelength for formation of yellow products from diphenylamine was at 2890 A. Irradiation of ethanol or benzene solutions 0.02 M in diphenylamine and l,4;3,6-dianhydro-D-glucitol-2,5-dinitrate (isosorbide dinitrate), followed by chromatographic separation, gave six organic compounds, two of which were isolated in pure form by adsorption chromatography and identified as 2- and 4-nitrodiphenylamine. Two other colored products were tentatively identified as N-nitroso- and p-nitrosodiphenyl-amine; no trace of the unreacted nitrate ester could be detected. Photolysis of isosorbide dinitrate alone in ethanol solution caused a weight loss of 17.7% in 21 hours and the formation of an unidentified hydrophilic, colorless sirup. A similar product was obtained on irradiation of an anhydrous benzene solution of the dinitrate. Possible mechanisms of the photolysis are discussed. / Science, Faculty of / Chemistry, Department of / Graduate