Низкая Селективность Реакций OH-радикалов С Алканами В Водных Растворах

The kinetics of the oxidation of functionalized organic compounds of atmospheric relevance by the hydroxyl radical (OH) was measured in the aqueous phase. Competition kinetics, using the thiocyanate anion (SCN − ) as competitor, was applied using both a laser flash photolysis long path absorption (LP-LPA) setup and a Teflon AF waveguide photolysis (WP) system. Both experiments were intercompared and validated by measuring the rate coefficients for the reaction between OH and acetone where values of k 1 = (1.8 ± 0.4) × 10 8 M −1 s −1 were obtained with the WP system, which agrees very well with the rate constant of k 1 = (2.1 ± 0.6) ×

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Cage effect and inverse temperature dependence of the kinetic isotope effect in the c‐C₆H₁₂/c‐C₆D₁₂ reaction with OH radicals in fenton and HOONOH₂O systems

Rudakov

Lobachev

Volkova

2011

Int J of Chemical Kinetics

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Recently, we have discovered the unusual inverse temperature dependence of the kinetic isotope effect (KIE) for the OH + c -C 6 H 12 /c -C 6 D 12 reaction in water. Temperature increase causes a KIE increase; this is valid for both the Fenton system (I) and the HOONO H 2 O system (II) (a new source of OH radicals in alkane reactions), whereas in the gas phase KIE decreases with increasing temperature. Results of these studies are considered. The KIE temperature dependences for both reactions in solution,The anomalous temperature behavior of KIE in water is described by a cage effect model at the step of the reactant encounter, which was proposed earlier by Rudakov. The model can be represented in a concise form:H 2 O, where RH··OH * is the oriented encounter complex in the water cage. It is suggested that elementary acts of H-abstraction (step 2) are identical for both gas phase and solution. It allows calculation of the competition parameter between steps 2 and -1 (the alkane leaves the cage via diffusion), by using the experimental KIEs.Correspondence to: E. S. Rudakov; e-mail: rudakove@ukr.net; V. L. Lobachev; e-mail: lmarvl@ivc.com.ua. c 2011 Wiley Periodicals, Inc. RUDAKOV, LOBACHEV, AND VOLKOVAA temperature-dependence average for systems I and II was found as (k −1 /k 2H ) = (245 ± 35) exp[(18.5 ± 0.5)/RT]. The hypothetical dependence of (k H /k D ) w on T was calculated within the overall temperature range (by extrapolations outside the experimental area, 278-328 K), and its connection with that of (k H /k D ) g on T is considered.

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Низкая Селективность Реакций OH-радикалов С Алканами В Водных Растворах

Cited by 25 publications

References 6 publications

Iron‐ and Cobalt‐Induced Activation of Hydrogen Peroxide and Dioxygen for the Selective Oxidation—Dehydrogenation and Oxygenation of Organic Molecules

Iron‐ and Cobalt‐Induced Activation of Hydrogen Peroxide and Dioxygen for the Selective Oxidation—Dehydrogenation and Oxygenation of Organic Molecules

Rate constants for the OH reactions with oxygenated organic compounds in aqueous solution

Cage effect and inverse temperature dependence of the kinetic isotope effect in the c‐C₆H₁₂/c‐C₆D₁₂ reaction with OH radicals in fenton and HOONOH₂O systems

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Низкая Селективность Реакций OH-радикалов С Алканами В Водных Растворах

Cited by 25 publications

References 6 publications

Iron‐ and Cobalt‐Induced Activation of Hydrogen Peroxide and Dioxygen for the Selective Oxidation—Dehydrogenation and Oxygenation of Organic Molecules

Iron‐ and Cobalt‐Induced Activation of Hydrogen Peroxide and Dioxygen for the Selective Oxidation—Dehydrogenation and Oxygenation of Organic Molecules

Rate constants for the OH reactions with oxygenated organic compounds in aqueous solution

Cage effect and inverse temperature dependence of the kinetic isotope effect in the c‐C6H12/c‐C6D12 reaction with OH radicals in fenton and HOONOH2O systems

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Product

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Cage effect and inverse temperature dependence of the kinetic isotope effect in the c‐C₆H₁₂/c‐C₆D₁₂ reaction with OH radicals in fenton and HOONOH₂O systems