Kinetics Of Alcohol Oxidation Research Articles

Cyclic voltammetric analysis of C 1–C 4 alcohol electrooxidations with Pt/C and Pt–Ru/C microporous electrodes

The effect of temperature on methanol, ethanol, 2-propanol, and 2-butanol electrooxidation is investigated with Pt/C and Pt–Ru/C microporous electrodes. Cyclic voltammetry is employed in temperatures ranging from 25 to 80 °C to provide quantitative and qualitative information on the kinetics of alcohol oxidation. Methanol displays the greatest activity atom alcohols. The addition of ruthenium reduces the poisoning effect, although it is ineffective with secondary alcohols. Secondary alcohols undergo a different oxidation mechanism at higher temperatures. Microporous electrodes provide detailed information on alcohol oxidation.

Reaction mechanism and kinetics of alcohol oxidation at nitroxyl radical modified electrodes

Abstract Nitrosonium cations generated by the one-electron oxidation of nitroxyl radicals are known to serve as selective oxidizing agents for alcohols to aldehydes or ketones. We prepared glassy carbon rotating disk electrodes (RDE) modified with 2,2,6,6-tetramethyl-piperidinyl-1-oxyl (TEMPO) via a very thin layer of poly(acrylic acid) and studied the electrode processes of 4-methoxybenzyl alcohol oxidation taking place at the modified electrodes in acetonitrile solution containing 0.2 mol dm −3 sodium perchlorate using cyclic voltammetry and RDE voltammetry. It was found that though the presence of a base such as 2,6-lutidine is essential for the alcohol oxidation to proceed at a reasonable rate, the limiting current values corresponding to the rate of the alcohol oxidation at the RDE scarcely depend on the lutidine concentration. On the basis of these findings and electrochemical characteristics of TEMPO modified electrodes, we considered three possible reaction mechanisms and derived corresponding equations which relate the limiting current to rotation frequency of the RDE and concentrations of the alcohol and the base. We analyzed the experimental data by using the derived equations and proposed as the most probable reaction mechanism the one giving the most reasonable kinetic parameters and in which the rate-determining step is the decomposition of an intermediate formed from the nitrosonium cation, the alcohol and the base.

Effect of ultrasound on the kinetics of oxidation of octan-2-ol and other secondary alcohols with sodium bromate, mediated by ruthenium tetraoxide in a biphasic system

The initial rate of oxidation of octan-2-ol and other secondary alcohols to their ketones with NaBrO 3, mediated by RuO 4 in an aqueous-CCl 4 biphasic system, is greater with ultrasonic irradiation than by stirring alone. Under ultrasonic irradiation the initial rate of oxidation of octan-2-ol increases with increasing % duty cycle, [RuO 4] and [NaBrO 3]. The kinetics of alcohol oxidation appear to be closely linked with the oxidative dissolution of RuO 2 to RuO 4 by NaBrO 3. The observed enhancement in rate with ultrasonic irradiation appear to be association, at least in part, with the increase in interfacial surface area via the formation of an emulsion of aqueous microdroplets containing NaBrO 3 in the CCl 4 layer containing the non-water-soluble secondary alcohol.