Proton transfer from heterocyclic compounds. Part 10. Adenine mono- and poly-nucleotides

Abstract

Detritiation rate constants from the C-8 position of adenosine 5′-monophosphate, adenosine 3′-monophosphate, adenosine 3′,5′-cyclic phosphate, and poly(adenosine 5′-monophosphate) have been measured over a pH range at 85°. The rate–pH profiles are of the same form as for adenosine with the important difference that for the first two compoounds an additional plateau region is obtained in the pH range where ionisation of the secondary phosphoric acid function occurs. The reactivity of the species formed (AMPH^–) is greater than it would otherwise be because it can also exist as a zwitterion (H⁺AMP^2–). Exchange from the polymer is ca. 30 times slower than for the mononucleotides.