Competition between the hydrolysis and deamination of cytidine and its 5-substituted derivatives in aqueous acid.

The monocations of a few 5-substituted cytidines have been shown to undergo competitive deamination to the corresponding uridines and hydrolysis to 5-substituted cytosines and D-ribose. The first-order rate constants measured at different temperatures indicate that the proportion of the hydrolysis is considerably increased with the increasing temperature. Electron-withdrawal by a polar substituent at C5 appears to facilitate the hydrolysis to a larger extent that the deamination. The ionic strength has practically no influence on the rate of either reaction.