The sonolysis of uracil

Abstract

The sonolysis of uracil (1) has been studied at 630 kHz in the presence of air, oxygen, nitrogen, and argon. The degradation products were identified by gc–ms analysis. Under aerated conditions the following products were found: uracil glycols (7), isobarbituric acid (8), N-formyl-N′-glyoxylurea (6), 5-hydroxyhydantoin (9), dialuric acid (10), alloxan monohydrate (12), parabanic acid (13), and oxaluric acid (14). In deaerated solutions 6, 13, and 14 were not observed but either 6-hydroxy-5,6-dihydrouracil(17) or its isomer (18) were detected in addition to 7, 8, 9, 10, and 12. The observed products have been used to develop a possible mechanism for the sonolytic degradation and the results are similar to those obtained in radiolysis.The sonolytic degradation of 5-bromouracil (19) is also reported; the products observed were 5-bromobarbituric acid (20), 12, 13, 14, and 9 and these can be rationalized by a similar mechanistic scheme.