Kinetic study of the oxidation of glyoxylic acid (HGl) by MnIII complex of (H2 salen=N,NI–bis(salicylidene)ethane–1,2–diamine.

Priyambada Jena

Volume : V, Issue : I, January - 2016

Kinetic study of the oxidation of glyoxylic acid (HGl) by MnIII complex of (H2 salen=N,NI–bis(salicylidene)ethane–1,2–diamine.

Priyambada Jena

Abstract :

The kinetics of oxidation of glyoxylic acid (HGl) by MnIII(salen)(OH2)+2 ((H2salen =N,N�–bis(salicylidene) ethane–1,2–diamine) is investigated at 25.0–35.0?C, 1.76≤pH ≤5.20, I =0.3 mol dm−3(NaClO4). The products are identified as formic acid, CO2 and Mn(II) with the reaction stoichiometry. The overall reaction involves fast equiliium pre–association of Mn(III)(salen)(OH2)+2 with HGl and its conjugate base Gl− forming the corresponding inner sphere complexes (both HGl and Gl−being the monohydrate gem–diol forms) followed by the slow electron transfer steps. The rate, equiliium constants and activation parameters for various steps are presented.MnIII(salen)(OH2)(Gl) is virtually inert to intra molecular electron transfer while the process is facile for MnIII(salen)(OH2)(HGl)+ reflecting the involvement of proton coupled electron transfer mechanism . MnIII(salen)(OH2)(HGl)/Gl)+/0+HGl/Gl− →products, shows that HGl for the (aqua)(HGl) complex is a better reducing agent than Gl−.