T. Yu. Filippova

New catalytic systems for selective oxidation of aromatic compounds by hydrogen peroxide

Abstract Some new water-soluble catalytic systems based on iron complexes of polyethylene oxide and block copolymers of ethylene oxide and propylene oxide functionalized by catechol or β-cyclodextrin have been developed. These complexes were examined as catalysts for biomimetic hydroxylation of benzene and phenol by hydrogen peroxide. It is shown that the introduction of β-cyclodextrin into the polyethylene oxide molecule is favourable for rate and selectivity of hydroxylation of aromatic compounds in a two-phase system.

Palladium nanoparticles on dendrimer-containing supports as catalysts for hydrogenation of unsaturated hydrocarbons

A new method has been proposed for encapsulation of palladium nanoparticles with a size of up to 2.5 nm in the matrix of special supports, the polymer networks based on poly(propylene imine) dendrimers, synthesized for this purpose. It has been shown that the particle size distribution of the materials obtained and their catalytic activity in the hydrogenation reactions of unsaturated compounds substantially depend on the specific features of the support structure. A high activity (TOF up to 15000 h−1) has been observed in the hydrogenation of styrene. The catalysts can be repeatedly used without loss of activity.

Mesoporous organic Pd-containing catalysts for the selective hydrogenation of conjugated hydrocarbons

Palladium catalysts supported on ordered organic mesoporous polymers were synthesized. The catalysts are characterized by the narrow size distribution of palladium nanoparticles with an average particle size of 2.2–5.2 nm. They demonstrate high catalytic activity and selectivity in phenylacetylene hydrogenation (896–2590 min−1, selectivity 89–98%). High activity and selectivity for alkenes are observed in the hydrogenation of conjugated dienes (for isoprene, TOF = 1850–5000 min−1, selectivity 99%; for 2,5-dimethyl-2,4-hexadiene, TOF = = 1294–2400 min−1, selectivity 100%; for 1,4-diphenyl-1,3-butadiene, TOF = 14–22 min−1, selectivity 7–16%). A dependence of the selectivity on the nature of the support and substrate was found for the hydrogenation of 1,4-diphenyl-1,3-butadiene.

Oxidation of unsaturated compounds in ionic liquids with the use of cyclodextrin-containing catalytic systems

The Wacker oxidation of alkenes-1 in ionic liquids catalyzed by a system containing palladium, and copper complexes and β-cyclodextrins was studied. It was shown that the use of β-cyclodextrins substantially increases the oxidation rate in biphasic systems olefin/ionic liquid. It was found that the proposed catalytic systems possess substrate selectivity, which is determined by the structure of a receptor molecule.

Hybrid catalysts based on platinum and palladium nanoparticles for the hydrogenation of terpenes under slurry conditions

Catalysts based on platinum and palladium nanoparticles immobilized in mesoporous phenolformaldehyde polymers modified with sulfo groups have been used for the hydrogenation of a number of terpenes, such as (S)-(–)-limonene, α-terpinene, γ-terpinene, and terpinolene. It has been found that Pd-containing catalysts exhibit higher activity in the exhaustive hydrogenation of terpenes, whereas Pt-containing catalysts have high selectivity for p-menthene.

Nickel–molybdenum sulfide catalysts supported on an ordered mesoporous polymer for hydrogenating–hydrocracking of model biaromatic petroleum compounds

Nickel–molybdenum sulfide catalysts have been synthesized in situ in a hydrocarbon medium by the decomposition of the [(n-Bu)4N]2Ni(MoS4)2 precursor complex supported on an ordered mesoporous phenol–formaldehyde polymer in the presence of a sulfiding agent (dimethyl disulfide). The catalytic properties of the samples have been studied in a batch reactor at 380°C and a hydrogen pressure of 5.0 MPa using the example of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene. The tests have shown that the conversion of biaromatic substrates is close to quantitative and the use of dimethyl disulfide as a sulfiding agent leads to an increase in the amount of complete hydrogenation products, as evidenced by the high content of the active phase in this case.

Use of ionic liquids in cyclohexene epoxidation with hydrogen peroxide

A comparative study of the reaction of catalytic epoxidation of cyclohexene with hydrogen peroxide in water and ionic liquids containing dihydrogen phosphate anions, such as trimethylammonium dihydrogen phosphate, diethylammonium dihydrogen phosphate, and N-methylpyrrolidonium dihydrogen phosphate has been performed. It has been shown that as high a cyclohexane epoxide yield as 80% with a selectivity close to quantitative can be obtained under optimum conditions by controlling the ratio of the ionic liquid components.

Guaiacol Hydrogenation in an Aqueous Medium in the Presence of a Palladium Catalyst Supported on a Mesoporous Dendrimer-Containing Polymer

Guaiacol hydrogenation in an aqueous medium in the presence of a palladium catalyst supported on a mesoporous dendrimer-containing polymer and the effect of addition of sulfuric acid to the catalyst system have been studied. It has been found that the main hydrogenation product is 2-methoxycyclohexanol. After the addition of sulfuric acid to the catalyst system, the reaction mechanism significantly changes and cyclohexanol becomes the main hydrogenation product.

H-D exchange of heterocyclic compounds on catalysts of various types

The H-D exchange of a number of oxygen-containing heterocyclic compounds with various deuterating agents, viz., D20, C6D6, and C2D5OD, was investigated. Group VIII metals and their salts and oxides, as well as carbon, aluminum oxide, aluminum silicate, and a metal zeolite, were used as catalysts. The mechanism of H-D exchange and the effect of the nature of the catalyst on its activity in the reaction are discussed.