Propane oxidation rate-determining step

The reactions of butane-2,3-diol by HCF in alkaline medium using Ru(III) and Ru(VI) compounds as catalysts leads to similar experimental rate equations for both the reactions. The mechanism involves the formation of a catalyst-substrate complex that yields a carbocation for Ru( VI) or a radical for Ru(III) oxidation. The role of HCF is in catalyst regeneration. The rate constants of complex decomposition and catalyst regeneration have been determined.89 A probable mechanism invoving formation of an intermediate complex has been proposed for the iridium(III)-catalysed oxidation of propane- 1,2-diol and of pentane-1,5-diol, butane-2,3-diol, and 2-methylpentane-2,4-diol with HCF.90-92 The Ru(VIII)-catalyzed oxidation some a-hydroxy acids with HCF proceeds with the formation of an intermediate complex between the hydroxy acid and Ru(VIII), which then decomposes in the rate-determining step. HCF regenerates the spent catalyst.93... 

Chromium(VI) oxide in various solvent systems provides an excellent oxidizing agent for alcohols, since it rapidly forms chromate esters which are intermediates in the oxidation of alcohols to aldehydes and ketones. The oxidation of [2- H]propan-2-ol showed a significant isotope effect when compared to propan-2-ol. Hence the abstraction of a proton by a base in the fragmentation of these esters is the rate-determining step in the reaction (Scheme 2.19). 

A Mechanism (a) involves a slow, rale-determining step producing the intermediate ester C, followed by a fast oxidation step. Since the C-H bond is not broken until after the rate-determining step, there should be no rate change if the propan-2-ol is replaced by Me2CDOH. Thus mechanism (a) can be ruled out. 

Possible Rate-Determining Steps (with Preceding Quasi-Equilibrium Steps Where Present) for the Oxidation of Propane and Platinum in Phosphoric Acid, 80°C-150°C and 0.30-5.0 V (Reversible Hydrogen Scale) (Work by G. Stoner)... 

Propan-2-ol is oxidized to acetone by two equivalents of Ag. The reaction is rapid and shows a first-order dependence on [Ag j, suggesting that direct participation of Ag in the reaction is unlikely. Disproportionation of Ag to form Ag and Agi i with direct oxidation by Ag would result in a second-order dependence on Ag. Stabilization of the tervalent form by a strong complex with alcohol can also be discounted since this would result in a zero-order dependence on alcohol, and not the first-order dependence observed. It is concluded that the reaction involves direct attack of Ag on propan-2-ol. Rate retardation by the addition of Ag was shown to be inconsistent with the formation of oxidatively inert Ag -ROH complexes and was explained by the existence of a back reaction in the rate-determining steps... 

Reaction network analyses for propane ammoxidation over a Ml-containing catalyst revealed that i) Mo and V in a framework structure are responsible for the oxidative activation of propane to propene, which is the rate-determining step ii) Te or Sb clearly promotes the conversion of the formed propene to acrylonitrile iii) the absence of Te or Sb clearly promotes the destructive conversion of propene to COx, and iv) the presence of Nb suppresses the further reaction of acrylonitrile, improving selectivity. 1,64, is 1,251,253,265-269... 

In the oxidation of propan-2-ol by chlorine water, two possible rate-determining steps can be considered ... 

The framework substitution of Mn(II) is responsible for a variety of phenomena (1) the high selectivity of the MnAPSO-34 toward formation of ethane in the reaction of methanol conversion (231), (2) the catalytic activity of MnAPO-5 in oligomerization of propane (232) and the catalytic activity of MnAPSO-44 in methanol dehydration (233), (3) the high yields in the production of isobutene and isobutene over MnAPSO-11 (234), (4) a sensor ability of MnAPO-5 to detect small molecules as CO, CO2, N,2 and H2O at room temperature (235), (5) MnAPO-5 registered to give 11% yield of p-IPEB and 5.8% yield of m-IPEB at 350°C in isopropylation of ethylbenzene with 2-propanol (236), and (6) cyclohexane (RH) reactions with O2 on MnAPO-5, where the oxidation rates are determined to be proportional to the number of redox-active Mn centers (237) The measurements by H2-O2 reduction-oxidation cycles indicate that these species act as active sites for kinetically relevant elementary steps in alkane oxidation catalytic cycles. 

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