Reactions of Cation Radicals of EE Systems. 5. Acid-Base Equilibria in Nucleophilic Reactions of Pyridine and Water with Thianthrene Cation Radical

John F. Evans, Henry N. Blount

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

The role of cation radical/nucleophile adduct deprotonation equilibria in the reactions of thianthrene cation radical (Th-+) with pyridine and water in acetonitrile solution has been examined using stopped-flow and electrochem-ical techniques. In both reactions reversible nucleophilic attack and adduct formation at a sulfur site on Th-+ is pro-posed as the first step in a general half-regeneration scheme. Rate-determining electron transfer involves reaction between adduct (oxidant) and deprotonated adduct in the case of a protic nucleophile (e.g., water). In the case of an aprotic nucleophile (e.g., pyridine) the rate-determining encounter is between a nonadducted cation radical and adduct with the adduct functioning here as the reducing agent. The formation of the product of both reactions, thianthrene 5-oxide, is discussed in terms of the relative stabilities of the oxidized forms of these cation radical/nucleophile adducts.

Original languageEnglish (US)
Pages (from-to)976-982
Number of pages7
JournalJournal of Organic Chemistry
Volume42
Issue number6
DOIs
StatePublished - Jan 1 1977

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