Mechanism of Uncatalyzed and Osmium(VIII) Catalyzed Oxidation of L-alanine by Copper(III) Periodate Complex in Aqueous Alkaline Medium

作者：Lamani Shekappa D; Veeresh Tegginamat M; Nandibewoor Sharanappa T^*

来源：Synthesis and Reactivity in Inorganic Metal-Organic and Nano-Metal Chemistry, 2011, 41(4): 394-404.

DOI：10.1080/15533174.2011.556408

• diperiodatocuprate(III)
• kinetics
• L-alanine
• Os(VIII) catalysis
• oxidation

The kinetics of oxidation of the L-alanine (L-ala) by diperiodatocuprate(III) (DPC) was carried both in the absence and presence of osmium(VIII) catalyst in alkaline medium at constant ionic strength of 0.01 mol dm-3 spectrophotometrically. The involvement of free radicals was observed in both the reactions. The oxidation products in both the cases were acetaldehyde and Cu(II), identified by spot test and spectroscopic studies. The stoichiometry is the same in both cases; that is, [L-ala]:[DPC] = 1:2. The reaction was first order in [DPC] and has negative fractional order in [OH-] in both the catalyzed and uncatalyzed cases. The order in [osmium(VIII)] was unity. A mechanism involving the formation of a complex between L-ala and DPC in case of uncatalyzed reaction and a mechanism involving the formation of a complex between L-alanine and osmium(VIII) in case of catalyzed reaction were proposed. The reaction constants involved in the different steps of the mechanisms were calculated for both reactions. The catalytic constant (Kc) was also calculated for catalyzed reaction at different temperatures. The activation parameters with respect to slow step of the mechanisms were computed and discussed for both the cases. The thermodynamic quantities were also determined for uncatalyzed and catalyzed reactions.

• 出版日期2011