A New Approach to the Anodic Decarboxylation of Unsaturated Dicarboxylic Acids. Part 1: Fumaric, Maleic and Acetylenedicarboxylic Acids

The dipotassium salts of maleic, fumaric and acetylenedicarboxylic acids were electrooxidized and the reaction products were analyzed qualitatively and quantitatively by UV/VIS and FT-IR spectroscopy. Acetylene, carbon dioxide and carbon monoxide, along with polyynes, are the products obtained from maleic and fumaric acids. The best acetylene yields are obtained from fumaric acid and not from maleic acid, which gives the highest yield of carbon dioxide. High concentration and high current density lead to the formation of carbonaceous matter containing carbyne recognizable by triple-bond stretching. Anodic oxidation of acetylenedicarboxylic acid produces only a mixture of carbon dioxide, carbon monoxide and soluble polyynes; no free acetylene was detected. A total of 15 chemical reactions with their free energy were studied to explain the reaction products of anodic oxidation.