Theoretical investigation on the kinetics and thermochemisty of H-atom abstraction reactions of 2-chloroethyl methyl ether (CH<Subscript>3</Subscript>OCH<Subscript>2</Subscript>CH<Subscript>2</Subscript>Cl) with OH radical at 298 K

Kinetics and thermochemistry of the H-atom abstraction reaction of CH₃OCH₂CH₂Cl with OH radical have been carried out using dual level of methods. Initially, geometry optimization and frequency calculations are performed at M06-2X/6-31+G(d, p) level of theory, and energetic calculations are further refined using CCSD(T)/6-311++G(d, p) level of theory in order to characterized all stationary points on potential energy surface (PES). The result shows that H-atom abstraction from –OCH₂ site of CH₃OCH₂CH₂Cl is dominant path. The rate constants are calculated using canonical transition state theory at 298 K, which are found to be in good agreement with the experimental data. We have presented the standard enthalpies of formation for CH₃OCH₂CH₂Cl and the radicals generated during the H-atom abstraction using group-balanced isodesmic reactions scheme. The atmospheric lifetime of title molecule is also calculated.     

Porous xerogels with a bifunctional surface layer of the composition ≡Si(CH<Subscript>2</Subscript>)<Subscript>3</Subscript>SH/≡Si(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>H<Subscript>3</Subscript>

The sol-gel method with ethanol as a solvent and fluoride ion as a catalyst was used to prepare polysiloxane xerogels containing both 3-mercaptopropyl and n-propyl groups in the surface layer. An increase in the relative amount of n-propyltriethoxysilane in the initial reaction solution was found to result in the formation of xerogels with developed porous structures, which was accompanied by an increase in the specific surface area from 370 to 550 m²/g; simultaneously, other porous structure parameters such as sorption volume and pore size exhibited a tendency to increase. Atomic-force microscopy was used to show that the xerogels synthesized comprised aggregates of mean size 30 nm. An analysis of the IR and ¹³C cross-polarization magic angle spinning NMR data led us to conclude that the surface layer of bifunctional xerogels contained not only 3-mercaptopropyl and n-propyl groups but also silanol groups, part of nonhydrolyzed alkoxy groups, and H-bonded water molecules. The ²⁹Si cross-polarization magic angle spinning NMR spectra revealed the presence of structural units of the compositions T¹ [(≡SiO)Si(OR’)₂(CH₂CH₂CH₃) and/or (≡SiO)Si(OR’)₂(CH₂)₃SH, R’ = H, OCH₃, or OC₂H₅], T² [(≡SiO)₂Si(OR’)(CH₂CH₂CH₃) and (≡SiO)₂Si(OR’)(CH₂)₃SH], and T³ [(≡SiO)₃SiCH₂CH₂CH₃ and (≡SiO)₃Si(CH₂)₃SH] in the xerogels synthesized.     

Formation of the center of ignition in a CH<Subscript>3</Subscript>Cl–Cl<Subscript>2</Subscript> mixture under the action of UV light

The dependence of temperature on time is investigated using a microthermocouple at different distances from a UV light source in a mixture of chlorine and chloromethane. These relationships give an idea of the size and location of a center of photoignition. It is found that if the size of the reaction vessel in the direction of the luminous flux is much greater than the dimensions of the ignition center, the thermal expansion of a reacting gas mixture has a huge impact on such photoignition parameters as the critical concentration limits and the critical intensity of UV radiation. It is found that by increasing the length of the vessel, some chlorinated combustible mixtures lose the ability to ignite when exposed to UV light.     

Study of the stable tetrahedron LiVO<Subscript>3</Subscript>–Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>–KBr–LiKMoO<Subscript>4</Subscript> of the quaternary reciprocal system Li,KǁBr,VO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>

Phase equilibria in the stable tetrahedron LiVO₃–Li₂MoO₄–KBr–LiKMoO₄ of the quaternary reciprocal system Li,K∥Br,VO₃,MoO₄ were studied by differential thermal analysis. The composition (mol %) and melting point of the alloy corresponding to a quaternary eutectic were determined: (24.2% LiVO₃, 10.4% Li₂MoO₄, 13.5% KBr, 51.9% LiKMoO₄, 407°С).     

Reaction of the [B<Subscript>10</Subscript>H<Subscript>9</Subscript>O<Subscript>2</Subscript>C<Subscript>4</Subscript>H<Subscript>8</Subscript>]<Superscript>–</Superscript> anion with C-nucleophiles

The reactions of 1,4-dioxane-substituted closo-decaborate anion ([B₁₀H₉O₂C₄H₈]^–) with metal acetylenides, diethyl malonate, ethyl acetoacetate, triethyl orthoformate, acetylacetone, and malonodinitrile were studied. The reactions were shown to be accompanied with substituent ring opening and attachment of the corresponding pendant functional group. The obtained compounds were characterized by various physicochemical methods (IR and polynuclear NMR spectroscopy, ESI mass spectrometry).     

Oxidation of Iodo- and Bromo-Substituted Polymethylbenzenes in the System PbO<Subscript>2</Subscript>–CF<Subscript>3</Subscript>COOH–CH<Subscript>2</Subscript>Cl<Subscript>2</Subscript>

The oxidation of mono- and diiodo- and -bromo-substituted polymethylbenzenes (mesitylene and durene) in the system PbO₂–CF₃COOH–CH₂Cl₂ at room temperature (2–70 h) leads mainly to the formation of iodo- and bromobenzyl alcohols as result of oxidation of methyl group. The reaction involves intermediate formation of haloarene radical cations. ESR study of these radical cations made it possible to determine the structure of their singly occupied molecular orbitals a₂ or b₁ and interpret their reactivity.     

Iridium–Ruthenium Cluster Complexes with SnPh<Subscript>3</Subscript> Ligands from the Reaction of IrRu<Subscript>3</Subscript>(CO)<Subscript>13</Subscript>(μ-H) with HSnPh<Subscript>3</Subscript>

The reaction of IrRu₃(CO)₁₃(μ-H), 1 with HSnPh₃ in hexane solvent at reflux has provided the new mixed metal cluster compounds Ir₂Ru₂(CO)₁₁(SnPh₃)(μ-H)₃, 2 and IrRu₃(CO)₁₁(SnPh₃)₃(μ-H)₄, 3 containing SnPh₃ ligands. Compound 2 which was obtained in low yield (3%) contains one SnPh₃, two iridium atoms and two ruthenium atoms. The increase in the number of iridium atoms must have resulted from a metal–metal exchange process. The major product 3 (19% yield) contains an open cluster of one iridium and three ruthenium atoms with three SnPh₃ ligands and four hydride ligands. Both compounds were characterized structurally by single crystal X-ray diffraction analysis.     

Platinum–Ruthenium Cluster Complexes from the Reaction of Ru<Subscript>3</Subscript>(CO)<Subscript>12</Subscript> with Pt(PBu<Superscript>t</Superscript><Subscript>3</Subscript>)<Subscript>2</Subscript>

Three new platinum–ruthenium complexes: Pt₃Ru₃(PBu^t ₃)₃(CO)₁₂, 8, Pt₅Ru₃(PBu^t ₃)₃(CO)₁₂, 9 and PtRu₃(PBu^t ₃)₂(CO)₈(μ₃-PBu^t)(μ-H)₂, 10 were obtained from the reaction of Ru₃(CO)₁₂ with Pt(PBu^t ₃)₂. Compound 8 was obtained from this reaction when conducted at 25 °C. Compounds 9 and 10 were obtained when the reaction was conducted at 68 °C. The structure of 8 consists of a central triangular cluster of three ruthenium atoms with one Pt(PBu^t ₃) group bridging each of the three Ru–Ru bonds. The structure of 9 consists of a capped pentagonal bipyramidal cluster of eight metal atoms that is formed formally by the addition of two platinum atoms to 8. The structure of 10 contains a triangular cluster of three ruthenium atoms with a Pt(PBu^t ₃) group bridging one of the Ru–Ru bonds. A t-butyl phosphido ligand formed by degradation of a molecule of PBu^t ₃ bridges the three ruthenium atoms. This report is dedicated to the memory of Professor F. A. Cotton for his many pioneering contributions to inorganic and metal cluster chemistry.     

Glass Formation in the Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>–(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>SO–H<Subscript>2</Subscript>O System

The glass formation in the Al₂(SO₄)₃–(CH₃)₂SO–H₂O system was found for the first time. The competitive ability of ligands, dimethyl sulfoxide and water (which are strong donors), for entering the first coordination sphere of aluminum is considered. The possibility of mixed coordination of (CH₃)₂SO (via sulfur and oxygen atoms) in the first coordination sphere of aluminum with retention of the glass-forming ability of the sample was suggested on the basis of IR spectral study.     

Physicochemical properties of (CH<Subscript>3</Subscript>)<Subscript>2</Subscript>NH<Subscript>2</Subscript>Cl–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composites

Composite solid electrolytes were synthesized from the organic salt dimethylammonium chloride (1–x)C₂H₈NCl–xAl₂O₃. Their physicochemical properties were studied. In the starting C₂H₈NCl salt, there is a phase transition at 39°C accompanied by an increase in conductivity by two orders of magnitude. The conductivity of the high-temperature phase is 9.3 × 10^–6 S/cm at 160°C. A differential scanning calorimetry study showed that the salt in the composites spreads over the oxide surface and at x > 0.6 the salt melting enthalpy decreases to zero. The conductivity of the resulting composites was studied by impedance spectroscopy. It was shown that heterogeneous doping leads to a sharp increase in ion conductivity to 7.0 × 10^–3 S/cm at 160°C and a decrease in the activation energy to 0.55 eV.     

Thermodynamic Study of the 2PbTe–AgSbTe<Subscript>2</Subscript> System Using EMF Technique with the Ag<Subscript>4</Subscript>RbI<Subscript>5</Subscript> Solid Electrolyte

The work presents the results of studies of the 2PbTe–AgSbTe₂ system using the EMF technique with the Ag₄RbI₅ solid electrolyte in the temperature range of 300–430 K. Formation of a wide (0–80 mol % AgSbTe₂) region of PbTe-based solid solutions in the system is shown. Partial thermodynamic functions \(\left( {\overline {\Delta G} ,\overline {\Delta H} ,\overline {\Delta S} } \right)\) of alloyed silver are calculated on the basis of the equations of the temperature dependences of EMF. Potential-forming reactions are determined on the basis of the data on solid-phase equilibriums in the Ag₂Te–PbTe–Sb₂Te₃–Te system that are used to calculate standard thermodynamic functions of formation and standard entropies of (2PbTe) _x (AgSbTe₂)_1–x (x = 0.2; 0.4; 0.6; 08; 0.9) solid solutions.     

Tree of phases of the quinary reciprocal system Li,K || F,Br, MoO<Subscript>4</Subscript>, WO<Subscript>4</Subscript> and study of the stable tetrahedron LiF–KBr–Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>–Li<Subscript>2</Subscript>WO<Subscript>4</Subscript>

The quinary reciprocal system Li, K || F, Br, MoO₄, WO₄ was partitioned into simplexes using graph theory by writing an adjacency matrix and solving a logical expression. A tree of phases of the system was constructed. The tree of phases has a linear structure and consists of four stable partitioning tetrahedra, two stable pentatopes, and three stable hexatopes. In the quinary reciprocal system Li, K || F, Br, MoO₄, WO₄, crystallizing phases were predicted. The stable tetrahedron LiF–KBr–Li₂MoO₄–Li₂WO₄ of the quinary reciprocal system Li, K || F, Br, MoO₄, WO₄ was studied by differential thermal analysis and X-ray powder diffraction. There are no invariant equilibrium points in the tetrahedron. Continuous series of solid solutions Li₂Mo_xW_1–xO₄ do not decompose.     

Cutting Tetrahedron LiVO<Subscript>3</Subscript>–KBr–KVO<Subscript>3</Subscript>–LiKMoO<Subscript>4</Subscript> of the Quinary Reciprocal System Li,K||F,Br, VO<Subscript>3</Subscript>, MoO<Subscript>4</Subscript>

The cutting tetrahedron LiVO₃–KBr–KVO₃–LiKMoO₄ of the quinary reciprocal system Li, K||F, Br, VO₃, MoO₄ was studied by differential thermal analysis. The composition and melting point of the alloy corresponding to a quaternary eutectic were determined (11.3 mol % LiVO₃, 18.0 mol % KBr, 57.0 mol % KVO₃, 13.7 mol % Li₂MoO₄ + K₂MoO₄, 318°С).     

Cutting Element LiF–LiVO<Subscript>3</Subscript>–LiKMoO<Subscript>4</Subscript>–KBr of the Quinary Reciprocal System Li,K||F,Br, VO<Subscript>3</Subscript>, MoO<Subscript>4</Subscript>

The cutting element LiF–LiVO₃–LiKMoO₄–KBr of the quinary reciprocal system Li, K||F, Br, VO₃, MoO₄ was studied by differential thermal analysis. The composition and melting point of the alloy corresponding to a quaternary eutectic were determined (7.0 mol % LiF, 32.0 mol % LiVO3, 47.7 mol % Li2MoO4 + K2MoO4, 12.3 mol % KBr, 410°С).     

Secant Tetrahedron LiF–KBr–KVO<Subscript>3</Subscript>–LiKMoO<Subscript>4</Subscript> of the Five-Component Reciprocal System Li,K‖F,Br,VO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>

The secant tetrahedron LiF–KBr–KVO₃–LiKMoO₄ of the five-component reciprocal system Li,K‖F,Br,VO₃,MoO₄ was studied by differential thermal analysis (DTA). The composition corresponding to the quaternary eutectic (mol %) was determined to be the following: LiF, 6.0; KBr, 11.4; KVO₃, 57.0; Li₂MoO₄ + K₂MoO₄, 25.6; the melting temperature: 358°С.     

Effect of Calcination Temperature on the Catalytic Oxidation of Formaldehyde Over Co<Subscript>3</Subscript>O<Subscript>4</Subscript>–CeO<Subscript>2</Subscript> Catalysts

The effect of calcination temperature (350–650?°C) on the structure and catalytic activity of Co₃O₄–CeO₂ mixed oxides prepared by sol–gel method was investigated by XRD, H₂-TPR, O₂-TPD and formaldehyde (HCHO) oxidation. The Co₃O₄–CeO₂ calcined at 450?°C (Co₃O₄–CeO₂-450) exhibited the best performance, showing that the complete oxidation of HCHO was achieved at temperature as low as 80?°C. The results of characterizations revealed that the Co₃O₄–CeO₂-450 had excellent catalytic activity due to the larger specific surface area, the best reducibility and more abundant surface active oxygen species.     

Regularities of formation of complex oxides with the fluorite structure in the ZrO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The crystal and local structures of the complex oxides (1–x)ZrO₂ ? xY₂O₃ (YSZ) (x = 0.08–0.40) prepared by precipitation from solutions of metal salts followed by heat treatment in air were comprehensively studied by X-ray diffraction and Raman spectroscopy. Despite the same crystal structure type of the YSZ powders (cubic system, space group \(Fm\overline 3 m\) (225)), there are differences in the local structure of the samples. Comparison of the Raman spectra recorded at different laser excitation wavelengths provided the conclusion that the peaks observed in the Raman spectra of the YSZ samples with high yttrium content (x = 0.18–0.40) are likely to be due to luminescence of the powders.     

Kinetics and mechanism of the low-temperature oxidation of carbon monoxide with oxygen on a PdCl<Subscript>2</Subscript>–CuCl<Subscript>2</Subscript>/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst

A systematic study of the kinetics of the low-temperature oxidation of carbon monoxide with oxygen on a PdCl₂–CuCl₂/γ-Al₂O₃ supported catalyst was carried out over a wide range of the partial pressures of oxygen, water, and CO in order to test hypotheses on the reaction mechanism. It was shown that, as the temperature was increased from 20 to 38°C, rate of formation of CO₂ decreased and the apparent activation energy was about–40 kJ/mol. The hypotheses of different degrees of complexity concerning the reaction mechanism were formulated based on physicochemical data and a Langmuir–Hinshelwood model. Mechanisms in which carbon dioxide is formed on the interaction of the surface Pd(I) and Pd(II) complexes that include carbon monoxide and water with the surface complex of Cu(I) that coordinates oxygen were recognized as the most probable.