Mechanism of ruthenium tetroxide-catalysed oxidation of aldoses by alkaline N-bromoacetamide.

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]