J. Stemple, D. Peters
Jun 25, 1990
Citations
0
Influential Citations
8
Citations
Journal
Journal of Electroanalytical Chemistry
Abstract
Studies of the electrolytically induced, base-catalyzed isomerization of 1-phenyl-1-hexyne to 1-phenyl-1, 2-hexadiene in dimethylformamide containing tetra-n-butylammonium perchlorate have been performed with a glassy carbon rotating ring-disk electrode. With the disk and ring potentials properly set, the alkyne is reduced at the disk and the kinetically formed allene can be detected at the ring. Measurements of the collection efficiency have established a lower limit of 1.7 × 103 M−1 s−1 for the second-order rate constant for the self-protonation reaction between 1-phenyl-1-hexyne and its electrogenerated radical-anion, which is the process that controls the alkyne-to-allene rearrangement. In addition, evidence that the isomerization is occurring is seen in the appearance of an unusual pre-peak for the kinetically controlled reduction of allene at the rotating disk. Furthermore, through the use of simulated Levich plots to describe the four-electron reduction of 1-phenyl-1-hexyne to 1-phenylhexane at a rotating disk electrode, under conditions where no alkyne-to-allene rearrangement occurs, protonation of the electrogenerated radical-anion of 1-phenyl-1-hexyne appears to be a pseudo-first-order process with respect to water and the second-order rate constant for this reaction has been found to be approximately 1.5 × 104 M−1 s−1.