Electrooxidation of β-Dicarbonyl Compounds Using Ceric Methanesulfonate as Mediator: Some Kinetics and Spectroscopic Studies

β-Dicarbonyl compounds 2,4-pentanedione (I), 1,3-cyclohexane-dione (II), 1,3-diphenyl-1,3-propanedione (III), methyl acetoacetate (IV), dimethyl malonate (V), methyl cyanoacetate (VI), and malononitrile (VII) were submitted to electrocatalytic oxidation mediated by CeIV anodically generated from cerous methanesulfonate, Ce(CH3SO3)3. I, II, III, IV, and V decompose yielding their respective carboxylic acids, methyl alcohol and CO2, via a proposed tricarbonylic intermediate. Four electrons per mole are consumed in these reactions. VI and VII proved to be unreactive. The reactivity order found was I≅III>II>IV>V. The substrates that form larger quantities of enol in reaction medium (β-diketones) are the most reactive, followed by the β-ketoester that forms less enol and the diester that forms no enol. An enol–CeIV complex is formed and the electron transfer is postulated as being “inner sphere.”