Kinetics and mechanism of Ru(III) and Hg(II) co-catalyzed oxidation of d-galactose and d-ribose by N-bromoacetamide in perchloric acid Original Research Article

Kinetics of oxidation of reducing sugars d-galactose (Gal) and d-ribose (Rib) by N-bromoacetamide (NBA) in the presence of ruthenium(III) chloride as a homogeneous catalyst and in perchloric acid medium, using mercuric acetate as a scavenger for Br− ions, as well as a co-catalyst, have been investigated. The kinetic results indicate that the first-order kinetics in NBA at lower concentrations tend towards zero order at its higher concentrations. The reactions follow identical kinetics, being first order in the [sugar] and [Ru(III)]. Inverse fractional order in [H+] and [acetamide] were observed. A positive effect of [Hg(OAc)2] and [Cl−] was found, whereas a change in ionic strength (μ) has no effect on oxidation velocity. Formic acid and d-lyxonic acid (for Gal) and formic acid and l-erythronic acid (for Rib) were identified as main oxidation products of reactions. The various activation parameters have been computed and recorded. A suitable mechanism consistent with experimental findings has been proposed.