Kinetic study of ruthenium(VI)-catalyzed oxidation of 2-butanol by alkaline hexacyanoferrate(III)

Abstract

The oxidation kinetics of 2-butanol by alkaline hexacyanoferrate(III) catalyzed by sodium ruthenate has been studied spectrophotometrically. The initial rates method was used for kinetic analysis. The reaction rate shows a fractional-order in [hexacyanoferrate(III)] and [substrate] and a first-order dependence on [Ru(VI)]. The dependence on [OH Ϫ ] is rather more complicated. The kinetic data suggest a reaction mechanism involving two active catalytic species. Each one of these species forms an intermediate complex with the substrate. The attack of these complexes by hexacyanoferrate(III), in a slow step, produces ruthenium(V) complexes which are oxidized in subsequent steps to regenerate the catalyst species.

Experimental and Computational Kinetic Assessment of Ruthenium (III) Catalyzed Oxidation of Paracetamol by Hexacyanoferrate(III): A Mechanistic Pathway

“…However, complications can arise when using HCF (III) in an acidic medium, as the oxidant can become complexed by one of the reduced products, hexacyanoferrate (II). While reactions in an alkaline medium have been found to be less prone to this complication, they are generally not as fast due to the reduced oxidation potential of the [Fe(CN) 6 ] 3À /[Fe(CN) 6 ] 4À redox couple [4] To address this issue, a range of transition metal ions have been used as catalysts in alkaline medium, including Osmium(VIII), [5,6] Ruthenium (III), [7,8] (IV), [9] (VI), [10] and (VIII), [11] Rhodium(III), [12] Iridium(III), [13] Paladium(II), [14] Molybdenum (IV), [15] and Cu (II), [16] Ru (III) [17] in micellar medium. HCF (III) is a potent one-electron oxidant and has redox potential of 0.36 V. It can act as a proton or electron abstracting reagent in oxidation reactions.…”

“…Ruthenium (III) is a commonly used catalyst in electron transfer reactions, but its reactivity in both acidic and alkaline media is significant. As a result, researchers have studied the reactions of HCF (III) in alkaline media in the presence of different catalysts, including ruthenium(III), [7][8][9][10]13] palladium(II), [14,25,26] and osmium(VIII). [5,27,28] Ruthenium(III) has been extensively employed as a catalyst in HCF (III) reactions, both in acidic [29] and alkaline media, [30] as well as in other reactions.…”