Search

The kinetics of oxidation of three aldoses (glucose, mannose and galactose) by N-bromoacetamide (NBA) in the presence of an alkaline solution of RuO as catalyst and Hg(OAc) as co-catalyst and as a scavenger for bromide have been investigated. The main products of the oxidation are the corresponding aldonic acids. The reaction is zero order with respect to aldose and OH. First order dependence of the reaction on both NBA and RuO at low concentrations shifts to zero order at higher concentrations. Addition of acetamide decreases the reaction rate, while addition of Hg(OAc) has the opposite effect. No significant effect of ionic strength was observed. OBr is postulated as the reactive oxidising species and a mechanism involving co-catalysis by RuO and Hg is proposed. [ABSTRACT FROM AUTHOR]

The kinetics of Ru catalysed oxidation of erythritol (1,2,3,4-tetrahydroxybutane) and dulcitol (1,2,3,4,5,6-hexahydroxyhexane) by N-bromoacetamide (NBA) in HClO in the presence of Hg(OAc) as a scavenger for Br have been investigated. The reactions are zeroth order with respect to both alcohols, and first order at low concentration of NBA tending to zero order at high NBA concentrations. The oxidation rate is directly proportional to [Ru] and a positive effect on the rate is observed for [H] and [Cl] whereas a negative effect is observed for acetamide and ionic strength. DO and Hg(OAc) do not influence the oxidation rate; (HOBr) is postulated as the oxidising species. A suitable mechanism consistent with the observed kinetic data is proposed. [ABSTRACT FROM AUTHOR]