Phototransformation of 3-hydroxybenzonitrile in water

The photolysis of 3-hydroxybenzonitrile in water yields 2-amino-5-hydroxybe nzaldehyde (I), 3-hydroxybenzaldehyde (II) and cyanohydroquinone (III). I i s only observed at pH < 4 whereas II is yielded whatever the pH. Oxygen has no influence on the formation of I but partly inhibits that of II. III is only observed in oxygenated solutions and at pH < 7. The photoionization is likely to be the primary step in the mechanism of formation of II and III. On the other hand, the production of I might be explained by the photoisom erization of 3-hydroxybenzonitrile into a cyclic imine followed by hydrolys is. (C) 1998 Elsevier Science S.A. All rights reserved.