Portal de Periódicos da CAPES

Mechanism of Ir(III)‐catalysed and Hg(II)‐co‐catalysed oxidation of reducing sugars by N ‐bromoacetamide in acidic medium

2004; Wiley; Volume: 17; Issue: 3 Linguagem: Inglês

10.1002/poc.723

1099-1395

Ashok Kumar Singh, Shahla Rahmani, Bharat Singh, R. K. Singh, Manju Singh,

Metal complexes synthesis and properties

Abstract The kinetics of Ir(III)‐catalysed and Hg(II)‐co‐catalysed oxidation of D ‐glucose (Glu) and D ‐fructose (Fru) by N ‐bromoacetamide (NBA) were studied in acidic medium. The reactions follow identical kinetics, being zero order in each sugar concentration. The experimental results show a first‐order dependence on NBA and Ir(III) at low concentrations, but tending towards zeroth order at higher concentrations. A negative effect of variation of [H + ], [Cl − ] and [NHA] was observed whereas the ionic strength ( I ) of the medium has no influence on oxidation rate. The important feature of the reaction is that it follows a second‐order dependence on mercury(II) ion concentration at low concentrations, but it tends towards first order at higher concentrations. Various activation parameters were calculated and recorded. The corresponding acids were identified as the main oxidation products of the reaction. On the basis of the experimental findings, a suitable mechanism consistent with the observed kinetics was proposed. A comparative study was also made between the kinetic results of the present investigation and those of Ru(III)‐ and Pd(II)‐catalysed oxidations of reducing sugars. Copyright © 2004 John Wiley & Sons, Ltd.