The Ionisation Sequence of Hypoxanthine and 6‐Mercaptopurine

Abstract

Abstract The sequence of acid dissociation in hypoxanthine is 9 (7) → 1 and in 6‐mercaptopurine 1 → 9 (7). In the former compound, formation of either the mono‐ or the bis‐anion is accompanied by bathochromic shifts, in the latter by hypsochromic displacements. Analogous changes are observed upon conversion of these two purines into the respective O‐ and S‐methyl ethers.