The Photochemical Reaction of 4-Nitropyridine in the Hydrochloric Acid 2-Propanol Solutions under the Atmosphere of Oxygen

Abstract

The photochemical reaction of 4-nitropyridine in the hydrochloric acid-2-propanol solutions has been investigated under the atmosphere of oxygen. Photolysis of the 2 × 10^-3, 2 × 10^-2, and 1 × 10^-1 mol/l solutions of 4-nitropyridine gave 4-hydroxypyridine, N, O-di 4-pyridyphydroxylamine, and 4-hydroxylaminopyridine, respectively. By means of UV spectroscopy, it was found that N, O-di 4-pyridyphydroxylamine was formed in the dark by the condensation reaction of 4-hydroxylaminopyridine hydrochloride with 4-hydroxylaminopyridine, both of which were formed photochemically. The result of the quenching study and of the value of the intersystem crossing coefficiency of 4-nitropyridine hydrochloride suggested that the photochemical reaction which produced 4-hydroxypyridine proceeded via the triplet state of 4-nitropyridine hydrochloride. The nitrite and nitrate produced by the photolysis of 4-nitropyridine were assumed as the intermediates of the 4-hydroxypyridine formation.