Mechanism Of Ru Research Articles

Mechanism of Ru(III) catalysis in N-bromoacetamide oxidation of some glycols in perchloric acid media

The kinetics of ruthenium(III) chloride catalysis in the oxidation of diethylene glycol (DG) and methyl diethylene glycol (MDG) by N-bromo-acetamide (NBA) in perchloric acid media are reported. The reactions follow identical kinetics, showing zero-order dependence on NBA, but first-order on each of H +, Ru(III) and Cl − ions. The first-order kinetics with respect to glycol at low concentrations shifts to zero-order at higher concentrations. A negative effect of ionic strength is observed, while successive addition of acetamide, D 2O and mercuric acetate shows zero effect on the reaction rate. Various activation parameters have been computed. The products of the reactions were identified as the corresponding acids. A suitable mechanism consistent with the kinetic observations has been proposed.

Kinetics and mechanism of Ru(III)-catalysed oxidation of organic sulphides and triphenylphosphine by N-methylmorpholine N-oxide

The selective oxidation of thioethers to sulphoxides and of PPh3 to PPh3O can be effected by NMO in DMF as solvent in the presence of Ru(III) chloride as catalyst. Kinetic investigations indicate that the orders with respect to the catalyst and oxidant are one each. The order with respect to the substrate is variable being fractional order at low concentrations and zero at high concentrations. Spectrophotometric studies reveal the formation of a 1:1 complex between the substrate and the catalyst. A mechanism consistent with the above observations has been proposed and verified.

Kinetics and mechanism of Ru(III)-edta catalyzed oxidation of cis-cyclootene by molecular oxygen

The homogeneous oxidation of cis-cyclooctene with molecular oxygen catalyzed by potassium chloro(ethylenediaminetetraacetato)ruthenium(III), K[Ru(H-EDTA)Cl]·2H 2O, was investigated in the temperature range 310–335 K,μ = 0.1 M KC1 in 1:1 water-dioxane mixture. The rate of oxidation of cis-cyclooctene was found to be first order with respect to catalyst and cyclooctene concentrations, and one-half order in molecular oxygen concentration. Based on the kinetic data, a μ-peroxoruthenium(IV)cyclo-octene complex is suggested as an active intermediate for the formation of cyclooctene oxide as a major product. A small quantity of 2-cycloocten-1-ol was also obtained in the reaction. The formation of 2-cycloocten-1-ol may be explained on the basis of the formation of a peroxometallocycle involving the catalyst, cyclooctene and dioxygen, which gives rise to an ene insertion product. A free radical route for the formation of 2-cycloocten-1-ol can be ruled out on the basis of the absence of any hydroperoxide intermediate. The activation parameters for the oxidation step corresponding to the rate constant were also calculated. The high enthalpy of activation Δ H ‡ of 26.8 kcal mol −1 supports the O-O bond cleavage in either mechanism. The products were analysed by GLC, IR and NMR spectroscopies and by derivatization of the products.

Mechanism of Ru(III) catalysis in N-bromosuccinimide oxidation of some glycols in perchloric acid media

Kinetics of Ru(III)-catalysed oxidation of diethylene glycol (DG) and ethyl diethylene glycol (EDG) by N-bromosuccinimide (NBS) have been investigated in perchloric acid media in the presence of mercuric acetate. The results showed first-order dependence on each reactant. Sodium perchlorate, mercuric acetate and succinimide additions have negligible effect on the reaction rate. Successive additions of acetic acid and chloride ions increased and decreased the reaction velocity, respectively. A solvent isotope effect ( k 1D 2O/ k 1H 2O = 1.8 – 2.3 and 2.0 = 2.4 for DG and EDG, respectively) has been observed at 35 °C. Various thermodynamic parameters have been com- puted and recorded. A suitable mechanism in conformity with the kinetic results has been proposed.

Kinetics and mechanism of Ru(III) catalysed oxidation of some polyhydric alcohols by [formula omitted]-bromosuccinimide in acidic media

Kinetics of oxidation of ethylene glycol, glycerol, erythritol and dulcitol by acidic solution of N-bromosuccinimide (NBS) in presence of ruthenium(III) chloride as a homogeneous catalyst and mercuric acetate as scavenger in the temperature range of 30–50°C have been reported. The reactions follow identical kinetics, being first order in each NBS, substate and Ru(III). Zero effect of [H +], [mercuric acetate] and ionic strength has been observed. A negative effect of succinimide and acetic acid is observed while [Cl -] shows the positive effect on reaction velocity. Various activation parameters have been computed. The products of the reaction were identified as the coresponding acids. A suitable mechanism consistent with the experimental results has been proposed.

Mechanism of Ru(III) Catalysis in Bromamine-T Oxidation of Some Primary Alcohols in Acidic Media

Mechanism of Ru(III) Catalysis in Bromamine-T Oxidation of Some Primary Alcohols in Acidic Media

Kinetics and mechanism of Ru(III) catalyzed iodination of anisole and substituted anisoles by iodine monochloride in aqueous acetic acid

The order with respect to ICl and Ru(III) is unity and fractional with respect to [substrate]. The effect of varying [acid] is negligible at lower [HClO4] but at higher [acid] (>0.01 M) there is first order dependence on [H+]. The Hammett plot gives a ρ value of −1.6. A plausible mechanism has been postulated.

Kinetics and mechanism of Ru(III) catalyzed oxidation of Se(IV) by Ce(IV)

Kinetics and mechanism of Ru(III) catalyzed oxidation of Se(IV) by Ce(IV)