28795-95-1Relevant articles and documents
Oxidations catalyzed by osmium compounds. Part 1: Efficient alkane oxidation with peroxides catalyzed by an olefin carbonyl osmium(0) complex
Shul'pin, Georgiy B.,Kudinov, Aleksandr R.,Shul'pina, Lidia S.,Petrovskaya, Elena A.
, p. 837 - 845 (2007/10/03)
A carbonyl osmium(0) complex with π-coordinated olefin, (2,3-η-1,4-diphenylbut-2-en-1,4-dione)undecacarbonyl triangulotriosmium (1), efficiently catalyzes oxygenation of alkanes (cyclohexane, cyclooctane, n-heptane, isooctane, etc.) with hydrogen peroxide, as well as with tert-butyl hydroperoxide and meta-chloroperoxybenzoic acid in acetonitrile solution. Alkanes are oxidized to corresponding alcohols, ketones (aldehydes) and alkyl hydroperoxides. Thus, heating cyclooctane with the 1-H2O2 combination at 70 °C gave products with turnover number as high as 2400 after 6 h. The maximum obtained yield of all products was equal to 20% based on cyclohexane and 30% based on H2O2. The oxidation of linear and branched alkanes exhibits very low regio- and bond-selectivity parameters and this testifies that the reaction proceeds via attack of hydroxyl radicals on C-H bonds of the alkane. The oxygenation products were not formed when the reaction was carried out under argon atmosphere and it can be thus concluded that the oxygenation occurs via the reaction between alkyl radicals and atmospheric oxygen. In summary, the Os(0) complex is much more powerful generator of hydroxyl radicals than any soluble derivative of iron (which is an analogue of osmium in the Periodic System).
Hydrogen peroxide oxygenation of alkanes including methane and ethane catalyzed by iron complexes in acetonitrile
Shul'pin, Georgiy B.,Nizova, Galina V.,Kozlov, Yuriy N.,Cuervo, Laura Gonzalez,Su?ss-Fink, Georg
, p. 317 - 332 (2007/10/03)
This paper describes an investigation of the alkane oxidation with hydrogen peroxide in acetonitrile catalyzed by iron(III) perchlorate (1), iron(III) chloride (2), iron(III) acetate (3) and a binuclear iron(III) complex with 1,4,7-triazacyclononane (4). The corresponding alkyl hydroperoxides are the main products. Nevertheless in the kinetic study of cyclohexane oxidation, the concentrations of oxygenates (cyclohexanone and cyclohexanol) were measured after reduction of the reaction solution with triphenylphosphine (which converts the cyclohexyl hydroperoxide to the cyclohexanol). Methane and ethane can be also oxidized with TONs up to 30 and 70, respectively. Chloride anions added to the oxidation solution with 1 activate the perchlorate iron derivative in acetonitrile, whereas the water as additive inactivates 2 in the H 2O2 decomposition process. Pyrazine-2-carboxylic acid (PCA) added to the reaction mixture decreases the oxidation rate if 1 or 2 are used as catalysts, whereas compounds 3 and 4 are active as catalysts only in the presence of small amount of PCA. The investigation of kinetics and selectivities of the oxidations demonstrated that the mechanisms of the reactions are different. Thus, in the oxidations catalyzed by the 1, 3+PCA and 4+ PCA systems the main oxidizing species is hydroxyl radical, and the oxidation in the presence of 2 as a catalyst has been assumed to proceed (partially) with the formation of ferryl ion, (FeIV=O)2+. In the oxidation catalyzed by the 4+PCA system (TONs attain 240) hydroxyl radicals were generated in the rate-determining step of monomolecular decomposition of the iron diperoxo adduct containing one PCA molecule. A kinetic model of the process which satisfactorily describes the whole set of experimental data was suggested. The constants of supposed equilibriums and the rate constant for the decomposition of the iron diperoxo adduct with PCA were estimated.
Oxidations by Methyl(trifluoromethyl)dioxirane. 2. Oxyfunctionalization of Saturated Hydrocarbons
Mello, Rossella,Fiorentino, Michele,Fusco, Caterina,Curci, Ruggero
, p. 6749 - 6757 (2007/10/02)
The reaction of methyl(trifluoromethyl)dioxirane (1b), a novel dioxirane species, with two open-chain, four cyclic, and five polycyclic saturated hydrocarbons and two aralkyl hydrocarbons in CH2Cl2/1,1,1-trifluoropropanone has been studied; under mild conditions (-22 to 0 deg C), it gives alcohols and/or ketones (deriving from further oxidation of secondary alcohols) in high yields and within very short reaction times.Primary C-H bonds are not appreciably oxidized and high regioselectivities were determined for attack at tertiary over secondary C-H bonds, with theexception of norbornane, which showed opposite regioselectivity.The reaction is also highly stereoselective, since hydroxylations of cis- and trans-decalin and of cis- and trans-1,2-dimethylcyclohexane were found to be in each case stereospecific with retention.From kinetic data, Ea = 14.3 kcal mol-1 and log A = 9.9 were estimated for cyclohexane oxidation.Relative rates change in the order cyclohexane (0.78) octane (9.2) adamantane (146); cis-1,2-dimethylcyclohexane was observed to be 7-fold more reactive than its trans isomer, demonstrating remarkable discrimination for equatorial vs axial C-H attack (also noticed in the case of cis- and trans-decalin).The relative rate of oxidation of cumene vs ethylbenzene was found to be ca. 3.1 (after statistical correction), i.e., in sharp excess over values usually recorded in classical radical H-atom abstraction from benzylic position.Rate constants determined for the reactions of cumene and of ethylbenzene show the title dioxirane (1b) is more reactive than dimethyldioxirane (1a) by factors of ca. 600 and over 700, respectively.The whole of theobservations is better accommodated by an "oxenoid" mechanism, involving concerted O-atom insertion by dioxirane into C-H bonds of hydrocarbons.
