Kinetics of OH Reactions

Wine, P.H., Kreutter, N.M., Gump, C.A., Ravishankara, A.R. (1981) Kinetics of OH reactions with the atmospheric sulfur compounds H2S, CH3SH, CH3SCH3, and CH3SSCH3. J. Phys. Chem. 85, 2660-2665. 

Wine, P.H., Thompson, R.J. (1984) Kinetics of OH reactions with furan, thiophene, and tetrahydrothiophene. Int. J. Chem. Kinet. 16, 867-878. 

The kinetics of hydrolysis reactions maybe first-order or second-order, depending on the reaction mechanism. However, second-order reactions may appear to be first-order, ie, pseudo-first-order, if one of the reactants is not consumed in the reaction, eg, OH , or if the concentration of active catalyst, eg, reduced transition metal, is a small fraction of the total catalyst concentration. 

In every chemical reaction, there is a direct relationship between the rate at which the reaction occurs and the concentrations of the reactants. When we measure this relationship, we measure the kinetics of the reaction. For example, let s look at the kinetics of a simple nucleophilic substitution—the reaction of CH3Br with OH- to yield CH3OH plus Br-—to see what can be learned. 

Atkinson, R., Aschmann, S.M. (1988) Kinetics of the reactions of acenaphthene and acenaphthylene and structurally-related aromatic compounds with OH and NOs radicals, N2Os and 03 at 296 2 K. Int. J. Chem. Kinet. 20, 513-539. 

Kinetic and mechanistic studies of the reactivity Zn-Oh ( = 1 or 2) species in small molecule analogs of zinc-containing metalloenzymes, 41, 81 Kinetics and spectroscopy of substituted phenylnitrenes, 36, 255 Kinetics, of organic reactions in water and aqueous mixtures, 14, 203 Kinetics, reaction, polarography and, 5, 1... 

Atkinson R, Aschman SM, Carter WPL. 1982. Kinetics of the reactions of OH radicals with -alkanes at 299K. Int J Chem Kinetics 14 781-788. 

For the kinetics of a reaction, it is critical to know the rough time to reach equilibrium. Often the term "mean reaction time," or "reaction timescale," or "relaxation timescale" is used. These terms all mean the same, the time it takes for the reactant concentration to change from the initial value to 1/e toward the final (equilibrium) value. For unidirectional reactions, half-life is often used to characterize the time to reach the final state, and it means the time for the reactant concentration to decrease to half of the initial value. For some reactions or processes, these times are short, meaning that the equilibrium state is easy to reach. Examples of rapid reactions include H2O + OH (timescale < 67 /is at... 

Le Calve, S., G. Le Bras, and A. Mellouki, Kinetic Studies of OH Reactions with /.ro-Propyl, /.ro-Butyl,. See-Butyl, and Tert-Butyl Acetate, hit. J. Chem. Kinet., 29, 683-688 (1997b). 

Picquet, B., S. Heroux, A. Chebbi, J.-F. Doussin, R. Durand-Jolibois, A. Monod, H. Loirat, and P. Carlier, Kinetics of the Reactions of OH Radicals with Some Oxygenated Volatile Organic Compounds under Simulated Atmospheric Conditions, Int. J. Chem. Kinel., 30, 839-847 (1998). 

Mpgelberg, T. E O. J. Nielsen, J. Sehested, T. J. Wallington, and M. D. Hurley, Atmospheric Chemistry of CF3COOH. Kinetics of the Reaction with OH Radicals, Chem. Phys. Lett., 226, 171-177 (1994a). 

The cathodic pinacolisation of 2- and 4-acetylpyridine, which had been investigated by one of the present authors (231-233), offered the chance for a complete kinetic analysis as the respective current voltage curves are of reversible character. They allow for evaluation of the kinetics of consecutive reactions, and one can show that at low pH reaction, Eq. (45c) is only possible if strong surfactants are absent. Such surfactants, by occupying the electrode surface, displace ketyl radicals, RiR2(OH)C , from the electrode surface because the latter are relatively weakly adsorbed and cannot compete with strong surfactants in adsorption. Ketyl radicals dissolved in aqueous or organic solvents of low pH are protonated in a fast almost diffusion-controlled reaction. After protonation they are further immediately reduced to form the monomeric carbinol instead of the hydrodimer—the pinacol ... 

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