Synthesis of Boron–Nitrogen–Phosphorus Compounds from N-Silylphosphoranimines

Two modes of reactivity of N-silylphosphoranimines have been utilized to prepare the title compounds containing either B–N=P or Si–N=P–N–B linkages. First, silicon-nitrogen bond cleavage reactions of the N-silylphosphoranimines, Me₃SiN=PMe(R)OCH₂CF₃ (1: R=Me, 2: R=Ph), with various chloroboranes gave the new N-borylphosphoranimines, Ph(Me₂N)B–N=PMe₂OCH₂CF₃ (2) and [(Me₃Si)₂N](Cl)B–N=PMe₂OCH₂CF₃ (10). In other cases, however, the expected B–N=P products were unstable and cyclic phosphazenes [Me(R)P=N]_3,4 were obtained. Second, deprotonation-substitution reactions of the aminophosphoranimines, Me₃SiN=P(R)Me–N(R)H, were used to prepare a series of novel (borylamino)-phosphoranimines, Me₃SiN=P(R)(Me)–N(R)–B(NMe₂)₂ (18: R=Me, R=t-Bu; 19: R=R=Me; 20: R=Ph, R=t-Bu; 21: R=Ph, R=Me) and Me₃SiN=PMe₂–N(t-Bu)–B(Ph)X (22: X=NMe₂, 23: X=OCH₂CF₃). All of the new boron–nitrogen–phosphorus products were fully characterized by multinuclear NMR (¹H, ¹³C, and ³¹P) spectroscopy and elemental analysis.     

Electrosynthesis and biological properties of persulfate–chloride solutions

A method for electrochemical synthesis of medical solutions for oxidation of toxic substances in the human organism has been developed. The method is based on electrooxidation of sodium sulfate in the presence of chloride and NaOH microadditions (in amounts that provide рН 13) in a filter-press membrane electrolyzer. A diagram is presented for choosing the optimum ratio between the current density and the flow rate of electrolyte during the electrosynthesis of a medical solution. The use of an electrolyte of the suggested composition under the optimum electrosynthesis conditions leads to solutions with physiological рН values (7.2–7.4) and high oxidative ability with respect to Micrococcus sp. and Staphylococcus coag (–), but there was no injuring effect on blood cells.     

Synthesis and Characterization of Organoboryl Germanium (Ⅱ) Oxides Containing Ge-O-B and Ge-O-B-O-Ge Cores

Organoboryl germanium(Ⅱ) oxides were synthesized from the 1,4-addition reaction of L'Ge(L'=HC[C(CH_2)N(Ar)]C(Me)N(Ar),Ar=2,6-iPr_2C_6H_3) with selected monosubstituted arylboronic acids RB(OH)_2(R=2,6-Me_2C_6H_3,2,4,6-Me_3C_6H_2,1-Naph) at the molar ratios of 1:1 and 2:1.The mononuclear products RB(OH)OGeL(L=CH[C(Me)N(Ar)]_2,Ar=2,6-iPr_2C_6H_3;R=2,6-Me_2C_6H_3(1),2,4,6-Me_3C_6H_2(2),1-Naph(3)) containing the Ge-O-B core were obtained smoothly through the 1:1 reaction.However,the reaction of L'Ge with 2,6-Me_2C_6H_3B(OH)_2 in a 2:1 ratio gave only the mononuclear product(1) instead of the expected binuclear one.What's more,a new borate compound [(2,6-Me_2C_6H_3)_4B_5O_6]~-[H:C]~+(4)(:C=C[N(iPr)C(Me)]_2) was concomitantly formed when the in situ prepared L'Ge was used as the precursor.In contrast,the use of 2,4,6-Me_3C_6H_2B(OH)_2 or1-NaphB(OH)_2 as the organoboryl source in the similar reaction led to the formation and isolation of the binuclear products RB(OGeL)2(R=2,4,6-Me_3C_6H_2(5),1-Naph(6)) containing the Ge-O-B-O-Ge core in a straight way.Compounds 1~6 were determined by single-crystal X-ray diffraction analysis.     

Joint Conversion of Methane with Pentane on Alumina–Platinum Catalysts Modified with Zirconium Oxide under Nonoxidizing Conditions

Kinetics and Catalysis - The physicochemical properties of alumina–platinum catalysts with supports prepared by mixing aluminum and zirconium hydroxides have been studied. The chemisorption...     

Zirconium Doped Hydrotalcite-based NiAl Mixed Oxides——Enhanced Performance for Adsorption of SO2 and NO

In the present study, the adsorptive behavior of zirconium doped hydrotalcite-based NiAl mixed oxides for reducing NO and SO2 was compared. According to tlie experimental results, the Zr^4+ cations were partially dissolved in crystalline NiO phase. With the addition of Zr, new centers for oxygen release and storage were formed, Lewis acid strength increased, and weakly and strongly alkaline sites were expanded. Moreover, in situ FTIR(Fourier transfonn infrared spectroscopy) investigation demonstrated that the amounts of surface bisulfite, sulfite, nitrite and nitrate spe? cies ofZrNiAlO were much more than those ofNiAlO. On the whole, this study concluded that the addition of Zr^4+ to NiAlO works to improve this compound as major absorbent for SO2 and NO.     

Alumina ultrafiltration membranes derived from carboxylate–alumoxane nanoparticles

The fabrication of asymmetric alumina ultrafiltration membranes using acetic acid surface stabilized alumina nanoparticles (A-alumoxanes) has been investigated. Contacting α-alumina supports with an aqueous solution of A-alumoxane (after firing to 1000°C) yields a defect free alumina membrane with a thickness of ca. 2 μm. The alumoxane-derived membranes have a molecular weight cut-off in the range of 35,000–44,000 g mol⁻¹, high porosity, and a permeability that is comparable to or greater than that of commercially available alumina membranes. SEM and AFM show that the surface of the alumoxane-derived membranes is quite smooth and contact angles show that the membrane is hydrophillic. A comparison with commercial alumina and polymer membranes, as well as those derived from sol–gel methods is presented.     

Surface and Catalytic Properties of TiO2–ZrO2 Mixed Oxides

This paper reviews acid–base bifunctional catalysis and surface properties (morphology, composition, specific area, acidity/basicity, site density) on TiO₂–ZrO₂ (abbreviated as TZ) mixed oxides. The phase change from crystalline single oxides (TiO₂ and ZrO₂) to amorphous TZ mixed oxide results in decreasing grain size and site density, increasing surface area, acid/base amount and strength, and better activity/selectivity. Different acid–base bifunctional mechanisms (concerted, go-together, stepwise) were proposed to interpret the reaction behavior of various reactions (esterification, dehydration, dehydrogenation, isomerization, dehydrocyclization) over the acid–base bifunctional TZ catalysts.     

Texture–Strength Properties of the Alumina–Montmorillonite Composite

The texture characteristics and strength properties of the molded alumina–montmorillonite composite are studied. The mixture is obtained by mixing suspensions of activated clay and pseudoboehmite followed by drying (at 293 and 393 K) and calcination (at 873 K). It is a promising support for cracking and hydrotreating catalysts. The changes in the specific surface area; the volumes of micro-, meso-, macropore, and medium-size pores; and the strength of samples are studied by varying the montmorillonite concentration in the composite. The addition of 20–35 wt % clay largely results in a sharp in reduction of the macropore region and, correspondingly, provides the alumina oxide average strength of the extrudates of 10–12 MN/m², which is sufficient for industrial supports. This excludes the stage of standard acidic peptization from the technological scheme of alumina production. The complex study of the porous structure of the composite by adsorption and mercury porosimetry combined with elements of percolation theory makes it possible to predict the texture–strength properties of derivative materials.     

Carbon Dioxide Fixation Method for Electrosynthesis of Benzoic Acid from Chlorobenzene

Carbon dioxide fixation technique was developed as an alternative dechlorination method of chlorobenzenes.Electrolysis of chlorobenzene was carried out in a one-compartment cell fitted with an alu- minium anode and a platinum cathode.Electrolysis in N,N-dimethylformamide(DMF)solution contain- ing 0.1 M of tetrapropylammonium bromide(TPAB)at 0℃,100 ml/min of CO_2 flow rate and 120 mA/cm~2 of current density was found to be the optimum conditions of this electrocarboxylation,which gave 72% yield of benzoic acid from chlorobenzene.These conditions were then applied to 1,2-dichlorobenzene and 1,3-dichlorobenzene in order to convert them to their corresponding benzoic acids.     

Preparation and Characterization of Ion Exchange Resin-Supported Nickel Boride Catalysts

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Boron–Ligand Cooperation: The Concept and Applications

The term boron–ligand cooperation was introduced to describe a specific mode of action by which certain metal-free systems activate chemical bonds. The main characteristic of this mode of action is that one covalently bound substituent at the boron is actively involved in the bond activation process and changes to a datively bound ligand in the course of the bond activation. Within this review, how the term boron–ligand cooperation evolved is reflected on and examples of bond activation by boron–ligand cooperation are discussed. It is furthermore shown that systems that operate via boron–ligand cooperation can complement the reactivity of classic intramolecular frustrated Lewis pairs and applications of this new concept for metal-free catalysis are summarized.     

Solvent-Free Preparation of 5-(α-D-Glucosyloxymethyl)furfural from Isomaltulose–Choline Chloride Melts

5-(α-D-Glucosyloxymethyl)furfural, a versatile building block from renewable resources, was prepared from isomaltulose–choline chloride melts by acid catalysis. In this solvent-free process, moderate yields were achieved under mild reaction conditions.     

Influence of Method of Introduction of Cu- and Zn-Based Modifiers on the Properties of Chromia–Alumina Catalysts

Three methods of introduction of modifiers based on Cu and Zn compounds into the CrO_x/Al₂O₃ catalysts for dehydrogenation of light paraffin hydrocarbons are considered: Introduction from sol, introduction using successive impregnation technique and introduction of modifiers by impregnation along with precursor of chromium oxide. The obtained samples are studied by a complex of physical-chemical methods (XRD, UV-Vis spectroscopy, temperature-programmed reduction with hydrogen (TPR-H₂), X-ray fluorescent (XRF) spectrometry, low-temperature N₂ sorption). The catalytic properties of the samples are studied in kinetic mode in isobutane dehydrogenation. Cu- and Zn-modifiers are shown to influence on the peculiarities of reduction of Cr⁶⁺ and, hence, specify the state of active surface of CrO_x/Al₂O₃ catalysts formed in the reductive reaction medium. Not only do the states of modifiers influence on the initial activity of the catalyst, but also on its activity after oxidative regeneration. Introduction of modifiers by successive impregnation method results in formation of copper and zinc aluminates or defective spinels on the Al₂O₃ surface. When the active component is introduced, the modified surface of the support promotes formation and stabilization of Cr⁶⁺ sites that can undergo reversible reduction–oxidation and provide high activity and selectivity towards formation of isobutylene (>98%).     

Synthesis and Structure of New Cobalt–Carbonyl Complexes Containing Tellurium Atoms

Co₂(CO)₈ and Te₂O react to form the well known Co₄(CO)₁₀Te₂, Co₄(CO)₁₁Te₂ complexes and the two new cluster complexes CCo₆(CO)₁₂Te₂(1), and CCo₆(CO)₁₀Te₂(Te₃) (2). The structures of 1 and 2 were determined by X-ray analysis, together with the triphenylphosphine derivative of 1, CCo₆(CO)₁₁(PPh₃)Te₂(3), which was analyzed to clarify the disordered structure of the parent compound. Complex 1 is formed by a prismatic cluster of cobalt atoms with a carbon embedded in the cage; two tellurium atoms cap the triangular faces of the prism and each cobalt atom links two terminal carbonyl groups. The complex 2 has a similar prismatic cage CCo₆; two ₄-Te atoms cap two rectangular faces of the prism, while other two Te atoms bridge two edges of the triangular faces and are linked each other through a third Te atom. Electron counting gives for complex 2 92 electrons: the presence of two long Co–Co distances suggests that the two excess electrons are located on Co–Co antibonding orbitals. Crystal data for 1, space group C2/c, a = 12.845(2) Å, b = 13.449(2) Å, c = 13.246(2) Å, = 91.95(2)°, Z = 4, R = 0.097 for 2555 reflections; for 2, space group Pnna, a = 17.219(5) Å, b= 14.969(6) Å, c = 9.178(4) Å, Z = 4,R = 0.037 for 3103 reflections; for 3, space group P2₁/c, a = 9.288(2) Å, b = 14.920(6) Å, c = 26.300(9) Å, = 99.99(2)°, Z = 4, R = 0.037 for 4300 reflections. The vibrational analysis of the complex 1 was performed and most of the (CO), (₆C–Co), (Co–Co) and (Co–Co) modes were assigned. The (Co–Te) modes were interpreted on the basis of the intermolecular coupling, due to the close contact between neighboring clusters in one distinct direction in the crystal.     

Synthesis and Characterization of Nitrogen Heterocyclic Derivatives Containing Sulfur–Ether and Schiff Base

Abstract

A series of new nitrogen heterocyclic compounds containing sulfur–ether (8a–8f) and Schiff-base (9a–9q) functionalities were synthesized by the reaction of the pharmaceutical lead compound containing both benzimidazole and 1,2,4-triazole rings. The compounds were characterized by ¹H NMR, ¹³C NMR, FT-IR, HR-MS, and ESI-MS.     

Langmuir–Blodgett Monolayers and Films of Alkylated Tetraazacrowns Containing Metal Ions and Nanoparticles

The behavior of individual 1,7-dicetyltetraaza-12-crown-4 and its mixture with 1,4,7,10-tetracetyltetraaza-12-crown-4 in the Langmuir monolayers at the subphases containing Cu(II) ions or colloidal gold particles is studied. Based on the compression isotherms, the complexing ability of these amphiphilic cyclenes in a monolayer at the surface of aqueous dilute solutions of copper salt is established. It was shown that the fraction of complexes in a monolayer is proportional to the copper ion concentration in the subphase. Using surface balance, atomic force microscopy, and electron microscopy methods, it was revealed that the monolayer of dicetylcyclene at the surface of gold hydrosol binds nanoparticles from the subphase; the number of particles bound by the monolayer is proportional to their content in the hydrosol. The Langmuir–Blodgett films (LBF) of dicetylcyclene are prepared; their ability to bind copper ions from solution was disclosed by quartz crystal microbalance. The LBFs of dicetylcyclene containing gold nanoparticles in each layer are assembled.     

Synthesis and Characterization of Titanium-doped Ordered Mesoporous Alumina

Titanium-doped ordered mesoporous alumina with specific structural properties has been prepared by the evaporation induced self-assembly sol-gel method. The results show that the doped titanium helps to stabilize the ordered mesoporous alumina material without influencing the ordered mesoporosity. The textural properties of the obtained sample are related to the amount of doped titanium. When the molar ratio of aluminum to titanium(n(Al)/n(Ti)) is controlled as 10.2, the titanium-doped ordered mesoporous alumina exhibits high surface area(up to 218 m2 g-1), large pore volume(0.42 cm3 g-1) and narrow pore diameter(6.1 nm) after treating at 900 ℃, showing high thermal stability. Moreover, the obtained sample calcined at 900 ℃ still maintains ordered mesoporous structure and exhibits high thermal stability.     

Influence of Pore-expansion Agent on the Structure and Performance of Activated Alumina Synthesized from Waste Aluminum Sludge

1 INTRODUCTION The reactivity of activated alumina adsorbent is closely related to its specific surface area: the larger the specific surface area, the better its activity and adsorbent capability are. However, in reality, the prac- tically available specific surface area or effective spe- cific area has relationship with its pore structure[1]. Since many reactant molecules are difficult to enter the pores to react with whose radius is shorter than certain critical value, the increase of p…     

Corrosion–Electrochemical Behavior of Chromium Deposits Obtained from Sulfuric Acid Solutions Containing Oxalates

The corrosion–electrochemical behavior of chromium electrodeposits, which are formed in sulfuric acid solutions of Cr(III) containing oxalates, is studied by taking steady-state polarization measurements in a 0.5 M H₂SO₄ solution. No region of the metal's active dissolution is observed for such coatings, and the open-circuit potential is localized in the passivity region, i.e. it is substantially displaced in the positive direction as compared with that for metallurgic chromium or the coatings deposited from standard chromium-plating electrolytes. According to XPS data, the surface layer of the passive metal a few nanometers thick includes oxide compounds of chromium and also carbides formed during the coating electrodeposition. Specific features of the corrosion–electrochemical behavior of the deposits are attributed to the presence of carbide compounds of chromium in them, with the compounds playing the role of a cathodic alloying agent.     

Phase Equilibria and Crystal Structure of Complex Oxides in the La–Sr–Co–Ni– System

Phase equilibria in the La–Sr–Co–Ni–O system were studied in air at 1100°. The samples for the study were synthesized by the standard ceramic and citrate processes. The limiting solubility and structure of La_1-xSr_xCo_1-yNi_yO_3- and (La_1-xSr_x)₂Co_1-yNi_yO₄ solid solutions were determined by Xray powder diffraction analysis. La_1-xSr_xCo_1-yNi_yO₃- solid solutions with 0 x 0.5 have a distorted rhombohedral perovskitelike structure (R c space group). An increase in the strontium concentration reduces the rhombohedral distortions, and the compounds with x < 0.5 have an ideal cubic structure (Pm3m space group). (La_1-xSr_x)₂Co_1-yNi_yO₄ crystals have a tetragonal K₂NiF₄ type unit cell (I4/mmm space group). The relationships between unit cell parameters and compositions were obtained for singlephase La_1-xSr_xCo_1-yNi_yO_3- and (La_1-xSr_x)₂Co_1-yNi_yO₄ samples. The existence regions of La_1-xSr_xCo_1-yNi_yO₃- and La_1-xSr_x)₂Co_1-yNi_yO₄ solid solutions were distinguished on P–T phase diagrams.