Oxidation with the 'O-2-H2O2-vanadium complex pyrazine-2-carboxylic acid' reagent - 9. Oxidation of cyclohexene and decalin

The oxidation of cyclohexene with hydrogen peroxide catalyzed by a vanadium complex and pyrazine-2-carboxylic acid (PCA) in air results in the formation of cyclohex-2-enyl hydroperoxide as the main product and cyclohex-2-enol, cyclohex-2-enone, cyclohex-3-enyl hydroperoxide, cyclohex-3-enol, cyclohexanol, cyclohexane, and 1,2-epoxycyclohexane in lesser amounts. The composition of the products of oxidation of decalin isomers with the system in question is similar to those obtained in the photochemical oxidation with hydrogen peroxide in air and in the oxidation with air in the presence of anthraquinone. A proposed mechanism for the oxidation includes the initiation by hydroxyl radicals generated from hydrogen peroxide under the action of the V-PCA system.47224725

Hydrogen-peroxide epoxidation of natural olefins catalyzed by a dinuclear manganese complex

The complex of Mn(IV) with the macrocyclic N-containing ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (L) [L2Mn2O3](PF6)(2) catalyzes epoxidation of (+)-limonene in CH3CN solution at room temperature. Adding CH3COOH accelerates the reaction. The products are isomers of limonene epoxide with predominance of that with an epoxified ring double bond. Epoxidation of alpha- and beta-pinene by this system is less effective, apparently due to extensive steric shielding of the double bonds in the pinenes

Hydrogen peroxide oxidation of alkanes catalyzed by the vanadate ion-pyrazine-2-carboxylic acid system

Pyridine admixtures have a slight effect on the activity and selectivity parameters in the oxidation of alkanes with the O-2-H2O2-vanadate anion-pyrazine-2-carboxylic acid reagent in acetonitrile. This feature distinguishes this reagent, which oxygenates alkanes via the mechanism involving free hydroxyl radicals, from similar systems based on iron complexes that show unusual selectivity in alkane oxidation in the presence of pyridine (Gif systems). The data obtained may indirectly indicate that free hydroxyl radicals do not directly participate in alkane functionalization with the Gif system, at least in the principal reaction route.45641341

Oxidation of alkanes with m-chloroperbenzoic acid catalyzed by iron(III) chloride and a polydentate amine

Tetradentate amine N,N'-bis(2-pyridylmethylene)-1,4-diaminodiphenyl ether (compound 1) dramatically accelerates the oxidation of alkanes with MCPBA in acetonitrile catalyzed by FeCl(3), whereas N,N'-bis(2-pyrrolidinmethylene)-1,4-diaminodiphenyl ether (2) does not affect the reaction. The selectivity of the reaction in the presence of I is noticeably higher than that in its absence. On the basis of the kinetic study and selectivity parameters a mechanism has been proposed which includes the formation of a complex between a molecule of MCPBA and coordinated to ligand I iron ion. This complex decomposes to produce a Fe(II) derivative which is further oxidized by MCPBA to generate a (1(.)Fe=O)(4+) species reacting with both alkane and acetonitrile. Finally, alkyl hydroperoxide is formed which partially decomposes to produce more stable corresponding alcohol and ketone (aldehyde). (C) 2004 Elsevier B.V. All rights reserved.219225526