Linear free energy relationships in Ce(IV)-diacetone alcohol redox system catalysed by metal ions

Abstract

Transition metal ions like Ag(I), Mn(II), Cu(II), Co(II), Ni(II) have been employed as homogeneous catalysts in Ce(IV)-diacetone alcohol (DAA) redox reaction. The order in [Ce(IV)] is unity and that in [catalyst] or [substrate] fractional. The rate laws observed with all these metal ions have been found to be the same, suggesting the mechanism of catalysis to be similar. A mechanism, involving formation of a complex between the catalyst and DAA in a fast step followed. by oxidation of this complex by Ce(IV) in the slow step to the higher oxidation state complex before collapsing to give the products, is proposed. A linear correlation has been obtained between log <em>k" </em>(bimolecular rate constant) and <em>K </em>(formation constant of the complex) for the electron transfer step between metal ion catalyst and DAA.