James F. Rusling
1981
Citations
0
Influential Citations
16
Citations
Journal
Journal of Electroanalytical Chemistry
Abstract
Abstract Homarine (1-methyl-2-carboxypyridinium ion) and trigonelline (1-methyl-3-carboxy-pyridinium ion) are reduced at mercury electrodes in alkaline solutions by a one-electron transfer to the pyridinium ring. Analysis of polarographic wave shapes using deviation-pattern recognition, peak widths of cyclic voltammograms, analysis of the products of bulk electrolyses and dependences of E1/2 and Ep on scan rate, pH and concentration indicated that these reductions proceed by an EC2 mechanism, where the second-order chemical reaction is a homogeneous dimerization. The zwitterionic form of the pyridiniumcarboxylic acid, which predominates in alkaline solutions, undergoes reduction to form a pyridinyl anion radical. Two radicals then couple to yield a dimer dianion which is subject to protonation. The dimer can be oxidized at mercury electrodes.