THE BROMINATION OF URACIL AND THYMINE DERIVATIVES

Abstract

The bromination of 1,3-dimethyluracil, uracil, and thymine and of the nucleosides and nucleotides of the latter two compounds has been followed potentiometrically and spectrophotometrically. The results indicate that all the compounds except uracil react initially with 1 mole of bromine to form 5-bromo-6-hydroxy-hydropyrimidine derivatives. If the resulting compound still has a hydrogen at position 5 it may undergo dehydration on heating or with acid catalysis to form the corresponding 5-bromopyrimidine, which is then capable of further reaction with bromine. Uracil itself appears first to undergo substitution to 5-bromouracil, and then both the uracil and 5-bromouracil are brominated together to yield ultimately 5,5-dibromo-6-hydroxyhydrouracil.