Dependence of Mechanism on pH for Deuterium–Hydrogen Exchange in 1-Methyltetrazole-5-d. Transition Metal Ion Catalysis of a Deprotonation Process

Harold Kohn, Stephen J. Benkovic, R. A. Olofson

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22 Scopus citations

Abstract

The pH–rate profile of protium for deuterium exchange of 1-methyltetrazole-5-d in aqueous solution at 67.6° has been determined and used as a control experiment in a demonstration that σ complexation of a heteroaromatic substrate with a transition metal cation (Cu2+ and Zn2+ used) can have a major rate-enhancing effect on processes in which substrate ring substituents are eliminated to produce formal sp2 carbanion intermediates. The control experiment is itself of interest, since in addition to a flattened exchange rate minimum at pH 4, a rate maximum is found at –H0 1–1.5, well below the experimental H0 (ca. –2.4) for half-protonation of 1-methyltetrazole.

Original languageEnglish (US)
Pages (from-to)5759-5765
Number of pages7
JournalJournal of the American Chemical Society
Volume94
Issue number16
DOIs
StatePublished - Aug 1 1972

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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