Ruthenium catalysed oxidation of cyclohexanol

1982 ◽  
Vol 35 (6) ◽  
pp. 1245 ◽  
Author(s):  
P Becker ◽  
JK Beattie
Keyword(s):  
Aqueous Solution ◽  
Isotope Effect ◽  
Phosphate Buffer ◽  
Hydride Transfer ◽  
Deuterium Isotope Effect ◽  
Rate Law ◽  
Alkaline Aqueous Solution ◽  
Catalysed Oxidation

The oxidation of cyclohexanol by ferricyanide in alkaline aqueous solution is catalysed by micromolar concentrations of K3RuCl6. The rate law at 25.0�C in pH 11.9 phosphate buffer containing 0.50 M NaCl is -d[FeIII]/dt = [Ru](2klk2[alcohol][FeIII])/(2kl[alcohol] + k2[FeIII]) with kl 12 � 2 mol-1 1. s-1 and k2 (2.5 � 0.2) × 102 mol-1 1. s-1. A deuterium isotope effect of about 4 is observed when (D12)cyclohexanol is used. A mechanism consistent with these observations involves reduction of the RuIII catalyst by hydride transfer from the alcohol followed by reoxidation by ferricyanide to the original RulIII state.

Kinetic deuterium isotope effect in the reaction of methyl iodide with thiosulfate ion in aqueous solution

1970 ◽  
Vol 48 (9) ◽  
pp. 1452-1455
Author(s):  
Alfred V. Willi ◽  
Chong Min Won
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Isotope Effect ◽  
Methyl Iodide ◽  
Isotope Effects ◽  
Force Constants ◽  
Deuterium Isotope Effect ◽  
Model Calculations ◽  
Bending Force ◽  
Reaction Vessels

The kinetic deuterium isotope effect in the reaction of methyl iodide with thiosulfate ion in aqueous solution has been determined as follows: kH/kD (per 3D) = 0.966 (+0.02°), 0.968 (+10.00°), 0.970 (+19.98°). Kinetic experiments have been carried out in reaction vessels with no gas phase. The experimental data are compared with results of model calculations of isotope effects from force constants. Excellent agreement between experimental and calculated isotope effects may be obtained with the following values of the transition state bending force constants: fHCI = 0.295 mdyn Å, fHCS = 0.300 to 0.320 mdyn Å. These values are equal to 50–65% of the corresponding bending force constants in stable molecules.

Copper-Catalyzed Oxidation of Cyanide by Peroxide in Alkaline Aqueous Solution

1995 ◽  
Vol 48 (4) ◽  
pp. 861 ◽  
Author(s):  
JK Beattie ◽  
GA Polyblank
Keyword(s):  
Aqueous Solution ◽  
Copper Complexes ◽  
Final Concentration ◽  
First Order ◽  
Alkaline Aqueous Solution ◽  
Catalysed Oxidation ◽  
Complex Forms ◽  
Kinetics Of ◽  
Catalyzed Oxidation ◽  
Destructive Oxidation

The oxidation of cyanide by peroxide in alkaline aqueous solution is catalysed by copper complexes. In the presence of excess cyanide, copper(II) is reduced to form the tricyanocuprate (I) complex. The cyanogen oxidation product is hydrolysed with disproportionation to cyanate and cyanide:2CuII+2CN-→ 2CuI+(CN)2(CN)2+2OH- → OCN-+CN-+H2OCuI+3CN- ↔ Cu(CN)32-The stoichiometry and kinetics of the catalysed oxidation have been investigated. Hydrogen peroxide oxidizes coordinated cyanide with a rate that is first order in peroxide and first order in copper but independent of cyanide concentration in the presence of excess cyanide. Cu(CN)32-+H2O2→ Cu(CN)2-+OCN-+H2O Cu(CN)2-+CN-↔ Cu(CN)32- When the excess cyanide is consumed and Cu(CN)2- becomes the dominant species, the reaction becomes more complex and less efficient. Under certain conditions the stoichiometry revealed a peroxide-to-Cu(CN)2- ratio of about 6 : 1, instead of the minimum of 2.5:1 required for the oxidation of the coordinated cyanide to cyanate and the CuI to Cu(OH)2. This suggests that peroxide is consumed by a copper- catalysed disproportionation, in competition with oxidation of the coordinated cyanide. An intermediate yellow complex forms while peroxide is present, before Cu(OH)2 finally precipitates. The consequence of this mechanism is that the most efficient process for the destructive oxidation of cyanide has a high cyanide-to-copper ratio, to minimize the final concentration of Cu(CN)2- which consumes peroxide inefficiently. The rate of the reaction depends on the concentration of copper, however, which must be large enough for a satisfactory turnover.

Partial kinetic ‘resolution’ resulting from a deuterium isotope effect

1991 ◽  
Vol 0 (12) ◽  
pp. 801-802 ◽  
Author(s):  
Panayiotis Anastasis ◽  
Raymond Duffin ◽  
Christopher Gilmore ◽  
Karl Overton
Keyword(s):  
Isotope Effect ◽  
Kinetic Resolution ◽  
Deuterium Isotope Effect

Ferricyanide Oxidation of Butanol Homogeneously Catalysed by Chlororuthenium Complexes

1979 ◽  
Vol 32 (9) ◽  
pp. 1905 ◽  
Author(s):  
AF Godfrey ◽  
JK Beattie
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Linear Dependence ◽  
Rate Constants ◽  
Homogeneous Catalyst ◽  
Basic Solution ◽  
Rate Law ◽  
Kinetics Of ◽  
Solution Estimates ◽  
Butanol Concentration

The oxidation of butan-1-ol by ferricyanide ion in alkaline aqueous solution is catalysed by solutions of ruthenium trichloride hydrate. The kinetics of the reaction has been reinvestigated and the data are consistent with the rate law -d[FeIII]/dt = [Ru](2k1k2 [BuOH] [FeIII])/(2k1 [BuOH]+k2 [FeIII]) This rate law is interpreted by a mechanism involving oxidation of butanol by the catalyst (k1) followed by reoxidation of the catalyst by ferricyanide (k2). The non-linear dependence of the rate on the butanol concentration is ascribed to the rate-determining, butanol-independent reoxidation of the catalyst, rather than to the saturation of complex formation between butanol and the catalyst as previously claimed. Absolute values of the rate constants could not be determined, because some of the ruthenium precipitates from basic solution. With K3RuCl6 as the source of a homogeneous catalyst solution, estimates were obtained at 30�0�C of k1 = 191. mol-1 s-1 and k2 = 1�4 × 103 l. mol-1 s-1.

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