Mechanistic study of oxidation of d-arabinose by N-bromophthalimide in presence of micro-amount of chloro-complex of Ru(III) as a homogeneous catalyst

Abstract

The kinetics and mechanism of Ru(III)-catalyzed oxidation of d-arabinose (d-Ara) by N-bromophthalimide (NBP) in a acidic medium were investigated using titrimetric method for the redox reaction in the temperature range of 303–323 K. The reaction was first order with respect to [NBP] and [Ru(III)]. In both cases, the reaction followed identical kinetics with positive fractional order for [d-Ara] and [H+]. Negative effect with increase in [Cl−], [CH3COOH] and [acetonitrile] could also be observed. Erythronic acid and formic acid were identified as main oxidation products of the reaction. Reduced product of the oxidant i.e. phthalimide did not show significant effect on oxidation rate. Various activation parameters have also been evaluated. Finally a plausible mechanism has been proposed from the kinetic results, reaction stoichiometry and product analysis.

Keywords

• Kinetics
• Oxidation
• N-bromophthalimide
• d-Arabinose
• Ru(III) chloride
• Phthalimide (NHP)