ISOTOPE EFFECTS IN THE ELECTROCHEMICAL REDUCTION OF OXALIC ACID-D(2) AND BENZOIC ACID-D

The electrochemical reduction of model carboxylic acid at lead cathode s in deuterated media was studied for potential use in the synthesis o f special deuterated compounds. Oxalic acid-d2 in D2O gives good yield s of glyoxylic acid-d2. An unexpected large isotope effect of 5.3 +/- 1.7 was found in this reaction, leading to significant depletion of de uterium content in the aldehyde group. Benzoic acid-d in CD3OD/diluted D2SO4 yields benzyl alcohol-d, 7,7-d2. The isotope effect of 2.4 +/- 1.0 is within the expected range. No deuterium is incorporated into th e aromatic nucleus. Essentially unlabelled benzyl alcohol is obtained in CD3OH/dil. H2SO4.