Oxidation of ethers with dimethyldioxirane |
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Authors: | S A Grabovskiy Q K Timerghazin N N Kabal’nova |
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Institution: | (1) Institute of Organic Chemistry, Ufa Research Center of the Russian Academy of Sciences, 71 prosp. Oktyabrya, 450054 Ufa, Russian Federation;(2) Centre for Research in Molecular Modeling (CERMM) and Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke West, Montreal, Quebec, H4B 1R6, Canada |
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Abstract: | Oxidation of a series of tert-butyl ethers ButOR (R = Me, Et, CH2CH2Cl, Pri, Bui), diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, diisobutoxymethane, 1,4-dioxane, and tetrahydrofuran with dimethyldioxirane
(DMDO) was studied. The reaction kinetics obeys the second-order equation w = kDMDO]ether]. The rate constants in a range of 5–50 °C and the activation parameters of the reaction were determined. The
solvent effect on the oxidation rate was studied. The oxidation products are the corresponding alcohols and carbonyl compounds.
The competition between the nonradical (oxygen insertion) and radical mechanisms of the reaction is discussed. The reactions
of the parent dioxirane and DMDO with a series of methyl ethers MeOr’ (r’ = Me, Et, CH2CH2F, Pri) were studied by the density functional theory (DFT). The (U)B3LYP-6-311G(d,p) method was employed to calculate the geometry
and energies of the reactants and transition states. The data obtained indicate a possible increase in the probability of
oxidation via the radical route and an increase in the activation barrier for the substrates containing electron-withdrawing substituents.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2309–2318, October, 2005. |
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Keywords: | dimethyldioxirane ethers oxidation kinetics free radicals ab initio calculations |
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