RuCl 3 further catalyzes the oxidation of iodide ion by K 3 Fe(CN) 6 , already catalyzed by hydrogen ions. The rate of reaction, when catalyzed only by hydrogen ions, was separated graphically from the rate when both Ru(III) and H + ions catalyzed the reaction. Reactions studied separately in the presence as well as absence of RuCl 3 under similar conditions were found to follow second-order kinetics with respect to [I − ], while the rate showed direct proportionality with respect to [Fe(CN) 6 ] 4− ions retards the reaction velocity, while changing the ionic strength of the medium has no effect on the rate. With the help of the intercept of the catalyst graph, the extent of the reaction that takes place without adding Ru(III) was calculated and it was in accordance with the values obtained from the reaction in which only H + ions catalyzed the reaction. It is proposed that ruthenium forms a complex, which slowly disproportionates into the rate-determining step. Arrhenius parameters at four different temperatures were also calculated. C

Six aromatic aldehydes, two hydrocarbons, one cycloalcohol and one aromatic alcohol, viz. benzaldehyde, p-chlorobenzaldehyde, cinnamaldehyde, 4-methoxybenzaldehyde, o-hydroxybenzaldehyde, 4-hydroxy, 3-methoxybenzaldehyde, anthracene, phenanthrene, cyclohexanol and benzyl alcohol dissolved in acetic acid, were oxidized in quantitative to moderate yields by 50% H 2 O 2 in the presence of traces of RuCl 3 (substrate : catalyst ratio 85 400 to 387 500 : 1). Conditions for highest yields, under most economical conditions, were obtained. Higher catalyst concentrations decreased the yield. Oxidation in aromatic aldehydes is selective at aldehydic group only, and other groups remain unaffected. The extent of oxidation in phenanthrene depends on temperature or the relative amount of substrate or both. In this new, simple and economical method, which is environmentally safe and requires less time, oxocentered carboxylate species of ruthenium (III) probably catalyze the oxidation.

The aromatic compounds p-nitrobenzaldehyde, p-hydroxybenzaldehyde, naphthalene, toluene, catechol, quinol, aniline and toluidine dissolved in aqueous acetic acid or aqueous medium were oxidized in quantitative to good yields by 50% H 2 O 2 in the presence of traces of RuCl 3 (∼10 −8 mol; substrate/catalyst ratio 1488 : 1 to 341 250 : 1). Conditions for highest yields, in the most economical way, were obtained. Higher catalyst concentrations decrease the yield. Oxidation in aromatic aldehydes is selective at the aldehydic group only. In the case of hydrocarbons, oxidation results in the introduction of a hydroxyl group with >85% (in the case of toluene) selectivity for the ortho position. Formation of low-molecular-weight polyaniline was reduced to 10%, along with 90% formation of higher molecular weight polyaniline. In this new, simple and economical method, which is environmentally safe and requires less time, oxo-centered carboxylate species of ruthenium(III) in acetic acid medium and hydrated ruthenium(III) chloride in aqueous medium probably catalyze the oxidation.

IrCl 3 which is considered to be a sluggish catalyst in alkaline media, was found to surpass the catalytic efficiency of even osmium and ruthenium in acidic media in the oxidation of cyclopentanone and 2-methylcyclohexanone by cerium(IV) sulphate in aqueous sulphuric acid medium. It was observed that the order of the reaction shows direct proportionality with respect to low concentrations of the oxidant and alcohols, but tends to become independent of concentration at higher concentrations. On increasing the concentrations of externally added Cl À , H þ and Ce III ions, the rate of the reaction decreases sharply initially but the decrease in rate becomes less prominent as their concentration is increased. The rate of reaction is directly proportional with respect to IrCl 3 concentrations. Kinetic data suggest that the production of Ce III ion occurs before the rate-determining step. Parameters such as the energy of activation, free energy of activation and entropy data collected at five different temperatures suggest that cyclopentanone forms the activated complex more easily.