Mechanisms of Bromination of Uracil Derivatives. 5. Reaction of Uracil and 5-Bromouracil via Their Anions in Weakly Acidic Aqueous Solution

Article abstract of DOI:10.1021/jo01293a014

The rates of reaction of bromine with uracil, 1-methyluracil, 3-methyluracil, 1,3-dimethyluracil, 5-bromouracil, and 5-bromo-1,3-dimethyluracil have been measured in acidic, aqueous solutions (pH 0-5).For those derivatives having a methyl group at N1 the observed second-order rate constants are invariant with acidity, whereas for those derivatives having hydrogen at N1 they increase with decreasing acidity.These results suggest that reaction upon the anions of uracil, 3-methyluracil, and 5-bromouracil predominates at higher pH.The mechanistic implications of these findings are discussed.