L. M. Glukhov

Electrodeposition of rare earth metals Y, Gd, Yb in ionic liquids

The possibility of yttrium, gadolinium, and ytterbium electrodeposition from solutions of their triflates in different ionic liquids at 100°C was investigated. It was shown that these metals could be deposited on the cathode from electrolytes based on ionic liquids with quaternary ammonium cations, and these metals do not deposit from 1-butyl-2,3-dimethylimidazolium triflate. It was established that, in the case of butyltrimethylamonium triflate usage, metal deposition occurs on a copper electrode, and it does not occur on a platinum electrode, and in 1-butyl-1-methylpirrolidinium triflate, the reduction process is possible on both electrodes. Yb3+ reduction occurs step by step via Yb2+ formation. It was shown that the limiting stage of the cathode process is adsorption of a metal cation on the electrode.

Ionic liquids as heat transfer fluids: comparison with known systems, possible applications, advantages and disadvantages

The practical aspects and prospects of application of ionic liquids as heat transfer fluids are discussed. The physicochemical properties of ionic liquids (heat capacity, thermal conductivity, thermal and radiation stability, viscosity, density, saturated vapour pressure and corrosion activity) are compared with the properties of some commercial heat transfer fluids. The issues of toxicity of ionic liquids are considered. Much attention is paid to known organosilicon heat transfer fluids, which are considered to have much in common with ionic liquids in the set of properties and are used in the review as reference materials. The bibliography includes 132 references.

Mass spectrometric studies of 1-ethyl-3-methylimidazolium and 1-propyl-2,3-dimethylimidazolium bis(trifluoromethyl)-sulfonylimides

RATIONALE Ionic liquids ([Cat(+)][An(-)]) were believed to decompose before reaching vaporization temperatures, but recently some of them have been shown to vaporize congruently. Low-temperature vaporization of ionic substances is an intriguing phenomenon, so the vapor-phase composition and reactions of ionic liquids deserve more extensive study. METHODS Evaporation of two ionic liquids, [C2MIM(+)][Tf2 N(-)] and [C3MMIM(+)][Tf2N(-)], was studied by means of Knudsen effusion mass spectrometry. These liquids were also characterized using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, UV/Vis, IR, NMR spectroscopy, and elemental analysis. RESULTS The vaporization enthalpies of (118 ± 3) and (124 ± 2) kJ·mol(-1) were determined for [C2MIM(+)][Tf2N(-)] and [C3MMIM(+)][Tf2N(-)], respectively. The corresponding equations for their saturated vapor pressures are: ln(p{[C2MIM(+)][Tf2N(-)]}/Pa) = -(14213 ± 325)/(T/K) + (26.57 ± 1.04), ln(p{[C2MMIM(+)][Tf2N(-)]}/Pa) = -(14868 ± 221)/(T/K) + (27.19 ± 0.60). The MALDI studies (positive and negative ion modes) enabled detection of monomeric [Cat(+)] and [An(-)] ions, the cluster ions {[Cat(+)]2 [An(-)]}(+) and {[Cat(+)][An(-)]2}(-), and some complex anions {2[An(-)] + Na(+)}(-), {2[An(-)] + K(+)}(-), {2[An(-)] + Cu(+)}(-) and {3[An(-)] + Ca(2+)}(-). CONCLUSIONS Knudsen effusion mass spectrometry proved to be a valuable method to study the thermodynamics of ionic liquids. The saturated vapor pressure and vaporization enthalpy of [C3MMIM(+)][Tf2N(-)] were accurately determined for the first time. MALDI is also capable of providing indirect information on hydrogen bonding.

Synthesis and properties of dicationic ionic liquids containing a siloxane structural moiety

Five new ionic liquids formed by doubly charged cations containing a siloxane moiety and bis(trifluoromethylsulfonyl) imide anion are synthesized and characterized. Their thermal stability is studied by means of TGA; melting points (glass transition temperatures) and densities are measured. The temperature dependences of kinematic viscosity of the obtained ionic liquids are presented along with their approximations by the Vogel–Tammann–Fulcher equation.

Synthesis and properties of ionic liquids with siloxane-functionalized cations

Four novel ionic liquids with siloxane-functionalized cations were synthesized and characterized. Their thermal stability was studied by the TG method; glass transition points, viscosities, and densities were also measured.

Meso- and macroporous materials modified with amines for CO2 storage

Adsorbents of a new type for CO2 absorption on amine-modified meso- and macroporous carriers are more efficient than amine water solutions. Their adsorption capacity with respect to CO2 reaches 13–15 wt %, they are recyclable, and the rates of CO2 absorption and evolution are higher than those for the liquid systems of CO2 storage.

Spectral studies of catalysts of oxidative dehydrogenation of dimethyl ether to dimethoxyethane

Spectral methods (diffuse reflectance infrared Fourier transform spectroscopy, EPR) are used to study the adsorption of dimethyl ether and oxygen on a catalyst of oxidative dehydrogenation of dimethyl ether to dimethoxyethane. The formation of O2− superoxide paramagnetic species is revealed. A mechanism of the formation of dimethoxyethane is proposed.

Dicationic polysiloxane ionic liquids

Dicationic ionic liquids with bis(trifluoromethylsulfonyl)imide anions and dimethylimidazolic moieties linked by the polymeric siloxane chain in the cation structure have been synthesized. Thermal stability of the compounds synthesised was studied by TGA; glass transition temperatures, viscosities and volatility in vacuo were measured. Applicability of these ionic liquids as heat carriers under high dynamic vacuum conditions is shown.

Acetone condensation over CaO—SnO 2 catalyst

Aldol condensation of acetone was studied over solid base CaO—SnO2 catalyst in the 300—450 °C temperature range and at 15—75 atm pressure in a fixed-bed reactor. The main products are mesityl oxide and isophorone. The high stability of CaO—SnO2 catalyst performance was observed at pressure of 75 atm giving the acetone conversion of 36—41%. Increase in the temperature and pressure led to a simultaneous raise in acetone conversion. The maximum conversion of 41% was achieved at 400 °C, 75 atm and a flow rate of acetone of 8.1 g h–1 (g catalyst)–1.

Catalytic oxidative coupling of dimethyl ether under supercritical conditions

Catalytic oxidative coupling of dimethyl ether (DME) is studied for the first time under supercritical conditions. The oxidation of DME with molecular oxygen of air in the presence of the CaO-SnO2 catalyst is carried out in a substrate (DME) medium and in its mixtures with CO2 under the supercritical conditions (100 atm, 250–300°C). At 255°C, the maximum conversion of DME (≈40% at the ratio of the yields of monoglim and diglim about 2: 1) is achieved at a 20-fold (by volume) dilution of DME with supercritical CO2.