Tautomeric Equilibrium in Polyfluoroalkylated 5,6,7,8-Tetrahydrofurans by IR Spectroscopy

The tautomeric equilibrium in substituted 5,6,7,8-tetrahydroquinazolines was studied by IR spectroscopy. The effect of various substitutents in the pyrimidine ring and the solvent on the state of the tautomeric equilibrium was evaluated.     

New hybrid chelating sorbents with grafted 3-aminopropionate groups based on mixed silicon,aluminum, titanium,or zirconium oxides

A series of new hybrid organo-inorganic sorbents with the 3-aminopropionate chelating group was synthesized. The synthesis includes the copolycondensation (sol—gel method) of tetraethoxysilane, 3-aminopropyltriethoxysilane, and several modifiers (MeSi(OEt)₃, EtSi(OEt)₃, Ti(OEt)₄, AlONO₃, ZrOCl₂) followed by carboxyethylation with acrylic acid. The obtained chelating sorbents were characterized by elemental analysis, FT-IR and ¹H NMR spectroscopy, and thermogravimetry. The N-carboxylated sorbents have a higher sorption capacity with respect to metal ions (0.5–0.9 mmol g⁻¹, pH 6.3, NH₄OAc, 20 °C) than the starting sorbents with the primary amino group (0.05–0.2 mmol g⁻¹) and manifest high selectivity for copper(II) ion extraction. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1783–1788, August, 2005.     

Oxidation of 2,3,6-trimethylphenol on titanium dioxide xerogel by hydrogen peroxide in the absence of an organic solvent

Fundamental aspects of the synthesis of 2,3,5-trimethylbenzoquinone by oxidation of 2,3,6-trimethylphenol adsorbed on the surface of a titanium dioxide xerogel and on TiO₂ modified with powdered cellulose with hydrogen peroxide without any organic solvent involved in the process were studied.     

Synthesis of Cu(II)-containing TiO2-SiO2 binary xerogels by hydrolysis of a mixture of tetrabutoxytitanium, tetraethoxysilane, and copper(II) chloride in a water-ammonia atmosphere

A Cu(II)-containing binary xerogel TiO₂-SiO₂ was synthesized by joint hydrolysis of tetrabutoxytitanium, teraethoxysilane and copper(II) chloride dissolved in their mixture. The synthesis was performed in a vapor of 10% aqueous ammonia under static conditions. EPR spectroscopy was used to examine the state of Cu(II) in the xerogel matrix. Data on specific features of the behavior of saccharose within xerogel pores under heating were obtained. The catalytic activity of the xerogel was tested by the kinetic method on model reactions of hydrogen peroxide decomposition and oxidative dehydrogenation of trimethylhydroquinone.     

Production of poly(chlorosulfostyrene) by synthesis in a gel

Synthesis in a gel as a method for the preparation of poly(chlorosulfostyrene) by treating polystyrene with chlorosulfonic acid was proposed, which makes it possible to obtain a polymer with a total degree of functionalization of sulfo and chlorosulfo groups up to 1.0. The possibility of regulating the degree of chlorosulfonation in the range from 50 to 100% was shown. The composition and structure of the products of polymer-analogous transformations were characterized by elemental analysis, FTIR spectroscopy, and thermogravimetry with IR identification of the decomposition products. Chlorosulfonation in the gel makes it possible to achieve a high degree of functionalization even at lower temperatures, at room temperature, and at less time than compared with known methods.     

Synthesis and structure of fluoroalkyl containing lithium 1,3-diketonates

Russian Journal of General Chemistry - Methods of synthesis and IR, mass, NMR 1H, 19F, 13C spectra as well as X-ray analysis of fluoroalkyl containing lithium 1,3-diketonates are reviewed.     

Inhomogeneous depth distribution of fluorine atoms in PVDF upon radiative carbonization

Under the action of ionizing radiation on a PVDF film, fluorine and hydrogen atoms bound to its linear carbon chain with single chemical bonds detach. Free atoms and HF molecules diffuse toward the film surface and escape from it. As a result of irradiation of the sample surface, a fluorine concentration depth profile arises. The fluorine distribution in the PVDF films subjected to long-term X-ray exposure was studied using X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. Both methods yield close values of the fluorine concentration at a depth of ～10 nm.     

Synthesis of porous zirconium and titanium dioxides by hydrolysis of tetrabutoxyzirconium (tetrabutoxytitanium) with atmospheric moisture in the absence of acid-base catalysts with the use of cellulose and activated charcoal as matrices

Synthesis of porous zirconium and titanium dioxides was accomplished by a procedure that includes impregnation of cellulose and activated charcoal matrices with tetrabutoxyzirconium (tetrabutoxytitanium) solutions, hydrolysis of the precursors with atmospheric moisture at 25°C, burning the matrix, and incineration of xerogels at 850°C. Relationship between precursor solution concentration at impregnation stage, matrix type, and physicochemical properties of prepared materials was established.     

Synthesis of TiO2-SiO2 xerogels via the hydrolysis of a tetrabutoxytitanium-tetraethoxysilane mixture in aqueous ammonia and hydrochloric acid atmospheres

TiO₂-SiO₂ xerogels have been synthesized by the hydrolysis of tetrabutoxytitanium-tetraethoxysilane mixtures in a 10% aqueous ammonia vapor and concentrated hydrochloric acid vapor atmospheres under static conditions. The dependence of the physical and chemical properties of the xerogels on the synthetic conditions has been investigated.