Electrode processes in the oxidation of tetrahydroisoquinoline derivatives

James Y. Becker, Larry L. Miller, Frank R. Stermitz

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The electrochemical oxidation of the alkaloid laudanosine (Ia) to O-methylflavinantine (II) has been studied in acetonitrile solvent. Using cyclic voltammetry, rotating disc voltammetry and preparative electrolyses on several alkaloids, simple aliphatic amines and aromatic compounds, some aspects of the mechanism of this coupling reaction are elucidated. The first anodic wave for laudanosine at platinum has Ep=0.55 V vs. Ag/Ag+. The electrode rapidly becomes partially passivated at potentials above 0.5 V. This is due to a film which "dissolves" below 0.5 V, at a rate independent of the potential. It is shown that the reaction (Ia)→(II) proceeds at 0.5 V by initial oxidation of the amine moiety. If acids such as sodium bicarbonate are added to the anolyte the amine is protonated causing the first wave to disappear. Oxidation at 1.1 V under these acidic conditions produces the same product, but more rapidly and in significantly higher yield because electrode filming and side reactions resulting from the amine oxidation are abrogated.

Original languageEnglish
Pages (from-to)181-191
Number of pages11
JournalJournal of Electroanalytical Chemistry
Volume68
Issue number2
DOIs
StatePublished - 10 Mar 1976
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering (all)
  • Electrochemistry

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