New Observations on Tautomerism and Ionization Processes in Hypoxanthines and 6‐Thiopurines

D. Lichtenberg, F. Bergmann, Z. Neiman

Research output: Contribution to journalArticlepeer-review

Abstract

Ultraviolet spectra show that hypoxanthine and 6‐thiopurine are present in aqueous solution predominantly as 1H, 9H‐tautomers. However, a 3‐methyl group causes the imidazole ring to assume the 7‐NH form. The sequence of anion formation in hypoxanthine is 9(7) → 1 and in 6‐thiopurine 1 → 9(7). The NMR spectra suggest that the mono‐anion of hypoxanthine is a mixture of tautomers. Protonation always takes place in the imidazole ring, with the exception of 3‐methyl derivatives. In the latter, formation of mono‐cations involves the pyrimidine moiety.

Original languageEnglish
Pages (from-to)805-817
Number of pages13
JournalIsrael Journal of Chemistry
Volume10
Issue number4
DOIs
StatePublished - 1972
Externally publishedYes

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