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The alkaline solvolyses of adenine nucleosides proceed by two parallel routes. The one is cleavage of the glycosyl bond to a stable adenine and a sugar and these rates initially increase with alkali and then remain relatively constant at the higher alkalinities. Concomitantly, the imidazole ring is attacked and opened with subsequent cleavage of the ribosyl bond and loss of C-8 as formic acid to form compounds analogous to 4,5,6-triaminopyrimidine at rates that appear proportional to hydroxide ion concentrations even at the higher alkalinities. It follows that the latter route is favored at high alkalinities. The resultant 4,5,6-triaminopyrimidine degrades relatively rapidly to nonchromophoric compounds. The numbers of hydroxyl groups in the sugar moiety do not appear to have any highly significant effect on rates of alkaline hydrolyses. Adenosine and 2 '-deoxyadenosine have equivalent rates. Electron-withdrawing substituents on the adenine moiety increase alkaline solvolysis rates whereas electron-donating substituents retard. This is consistent with the kinetically observed hydroxyl ion attack. The alkali-induced recyclization of 1 -methyladenosine that occurs under room temperature and mildly alkaline conditions yields W6-methyladenosine which subsequently solvolyzes at high alkalinities and temperatures, e.g., 80°, in the manner previously cited for adenine nucleosides. he effect of glycosidic structure and substituents in

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