A role of non-hydrogen framework vibrational modes in formation of ferroelectric properties of H-bonded K3H(SO4)2-like materials

An effect of molecular vibrational modes within the dimers [O₃AO–(H/D)OAO₃]³⁻ on behavior of H-bond protons or deuterons is studied theoretically for H-bonded antiferroelectrics and quantum paraelectrics of the M₃(H/D)(AO₄)₂ family (M=alkali metal, A=S, Se). The ‘heavy’ reorganization modes in D-species of this family and both reorganization and promoting modes in corresponding H-analogues are examined. It is shown that the analysis with due regard for the reorganization modes results in insignificant decreasing of the effective tunneling frequency of light nuclei. Hence the reasonable estimations of the critical temperature of the low-temperature phase transition in M₃D(AO₄)₂ materials are available only with additional corrections related to potential profiles of a deuteron. It is noted that in the limits of the proposed model the promoting mode in the case of H-species can favor, in principle, the increasing as well as the decreasing of effective proton level splitting.     

Use of the wittig reaction for synthesizing 2-deoxy-L-glucose

Conclusions The Wittig reaction was carried out between 2,3:4,5-diisopropylidene-al-L-arabinose and tolyloxy-methylenetriphenylphosphorane, and 2-deoxy-L-glucose was synthesized in a high yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 892–895, April, 1970.     

Microcalorimetric Study of Water Adsorption on Initial and Polyfluoroalkylated Silicas

Water adsorption on initial and modified Silochrom samples was studied by the adsorption calorimetry. Integral heats of immersional wetting by water were measured simultaneously. It was shown that hydroxyl groups both free and sterically screened by a modifier remain on the modified Silochrom surface. Concentrations of these groups and OH groups chemically interacted with the modifier were estimated. The heat of reaction of water molecules with a free surface OH groups of modified sorbents was determined (≈60 kJ/mol). It was found that the modifying layers of the sorbents are getting loose under the effect of adsorbed water, and water molecules gain access to the sterically screened OH groups; the heat of water interaction with these groups is 54–55 kJ/mol. The energy is consumed for getting the modifying layers loose and the rupture of point contacts between Aerosil particles of the secondary structure of both initial and modified Silochrom that significantly affects the heat of immersion, the differential heat of adsorption, the form of the heat release curve, and the dependence of the differential heat on the adsorption value.     

Ion-exchange equilibria and exchange heats on clinoptilolite involving singly-charged cations

Isotherms and integral heats of exchange of alkali metal, ammonium, and silver cations on sodium clinoptilolite were measured. Exchange involving K₊, NH₄ ⁺, Cs⁺, and Ag⁺ displacing cations was found to be exothermic for all occupancies of the clinoptilolite exchange sites. Exchange was exothermic for Li₊ cations up to = 0.15. The dependence of the differential ion-exchange heats on was determined. Clinoptilolite was found to have two types of exchange sites with different heats of ion exchange. The experimental data were used to calculate the selectivity coefficients, thermodynamic constants, and ion-exchange entropy. These findings are discussed relative to the differences in the cation properties and structural features of clinoptilolite.A. V. Dumanskii Institute of Colloid Chemistry and the Chemistry of Water, National Academy of Sciences of Ukraine, 42 Prospekt Akademika Vernadskogo, 252680 Kiev-142, Ukraine. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 5, pp. 315–319, September–October, 1996. Original article submitted February 12, 1996.     

Synthesis and spectral-luminescence properties of hetarylethylene derivatives of 2,5-diphenyloxazole and 2,5-diphenyl-1,3,4-oxadiazole

A number of new organic luminophores was synthesized by PO olefination from 2- (4-bromomethylphenyl)-5-phenyloxazole and -1,3,4-oxadiazole and various heterocyclic aldehydes that contain a furan ring. The absorption and fluorescence spectra of the products in toluene, as well as their scintillation characteristics, were measured. The effect of the electronic nature of the substituents on the spectral-luminescence properties of the luminophores is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 617–621, May, 1982.     

Weakly coordinating anions HA2-generated from oxoanions A- and their conjugate acids. Coordination equilibria,ionic conductivities,and the structures of [Cu2(H(CH3SO3)2)4]n and [Cu(CO)(H(CF3CO2)2)]2

The coordination or ion pairing of the hydrogen-bonded anions H(CF3CO2)2- and H(CH3SO3)2- to NEt4+, Li+, Cu+, and/or Cu2+ was investigated. The structure of [Cu2(H(CH3SO3)2)4]n consists of centrosymmetric dimeric moieties that contain two homoconjugated (CH3SO2O-H...OSO2CH3)- anions per Cu2+ ion, forming typical Jahn-Teller tetragonally elongated CuO6 coordination spheres. The oxygen atoms involved in the nearly linear O-H...O hydrogen bonds (O...O approximately 2.62 A) are not coordinated to the Cu2+ ions. The structure of Cu2(CO)2(H(CF3-CO2)2)2 consists of pseudo-C2-symmetric dimers that contain one homoconjugated (CF3COO-H...OCOCF3)- anion per Cu+ ion, forming highly distorted tetrahedral Cu(CO)O3 coordination spheres. Three of the four oxygen atoms in each hydrogen-bonded H(CF3CO2)2- anion are coordinated to the Cu+ ions, including one of the oxygen atoms in each O-H...O hydrogen bond (O...O approximately 2.62 A). Infrared spectra (v(CO) values) of Cu(CO)(CF3CO2) or Cu(CO)(CH3SO3) dissolved in acetonitrile or benzene, with and without added CF3COOH or CH3SO3H, respectively, demonstrate that HA2- anions involving carboxylates or sulfonates are more weakly coordinating than the parent anions RCO2- and RSO3-. Direct current conductivities of THF solutions of Li(CF3CO2) containing varying concentrations of added CF3COOH further demonstrate that Li+ and NEt4+ ion pair much more weakly with H(CF3CO2)2- than with CF3CO2-.     

Polarographic examination of 5-aryl-2-(2-thienyl)-oxazoles and -1,3,4-oxadiazoles

The polarographic behavior of 5-aryl-2-(2-thienyl)oxazoles and -1,3,4-oxadiazoles has been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1550–1552, November, 1986.     

Thermodynamic investigation of the state of water adsorbed by carbonaceous adsorbents

The state of water adsorbed on active carbons and canal soot was studied using the “chemical potential—entropy—temperature” diagram. In the range of the relative pressures from 0.174 to 1, the state of adsorbed water is similar to the state of a stretched liquid. The molar volume, heat of evaporation, and surface tension of stretched water were calculated at different relative pressures. Near the spinodal, the molar volume of stretched water is 25% higher, and the surface tension is considerably lower compared to water. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 464–468, March, 1997.