Acid-catalysed Hydrolysis of Nucleosides

The plots of logiokobs versus pH (or //q) are linear, of gradient 1.0 for guanosine, 2 -deoxyguanosine and 2 -deoxyadenosine, over most of the accessible range, passing through the pK of N7 ( 3) without detectable inflection 

7-dimethylguanosine and 2 -deoxy-7-methylguanosine, which all hydrolysed in a pH-independent fashion until high acidity, when the rates were similar to those of the unmethylated compounds. In very concentrated perchloric acid, a levelling off of the rate of methylated and unmethylated substrates alike could 

Psicofuranine likewise hydrolyses via both mono- and dication, although in this case a point of inflection around pH = pKi of N7 is discernible in the logio obs versus pH plots.  

Purine nucleoside hydrolysis decelerated by bridging with 3, 5 -cyclic phosphate 

---