Showing papers on "Halide published in 1992"

Platinum complexes and use thereof

Abstract: Method for preparing a platinum-organosiloxane complex which comprises reacting a platinous halide with an organo-siloxane having from 2 to 4 silicon-bonded organic groups containing terminal olefinic unsaturation, the reaction being carried out in the presence of a polar organic liquid, for example dimethylformamide or butan-2-one, which is at least a partial solvent for the platinous halide. The acomplexes are useful as catalysts for hydrosilylation reactions.

Preparation of monolithic gels from silicon halides by a non-hydrolytic sol-gel process

Abstract: Reactions of organic oxygen compounds, such as ter-butanol, benzylalcohol, dibenzylether and benzaldehyde, with silicon halides provide a novel non-hydrolytic sol-gel route to silica.

Carbon dioxide as a C1 building block. Mechanism of palladium-catalyzed carboxylation of aromatic halides

Abstract: The reduction of aryl halides in the presence of stoichiometric amounts of carbon dioxide and catalytic amounts of Pd II Cl 2 (PPh 3 ) 2 has been previously reported to result in the formation of the corresponding carboxylic acids. It is shown here that the mechanism proceeds via a catalytic cycle initiated by the one-step, two-electron reduction of the divalent palladium complex followed by oxidative addition of the aryl halide to the resulting poorly ligated zerovalent palladium center «Pd 0 (PPh 3 ) 2 », to afford the corresponding σ-arylpalladium(II) intermediate

Experimental determination of the thermal diffusivity of molten alkali halides by the forced Rayleigh scattering method. I : Molten LiCl, NaCl, KCl, RbCl, and CsCl

Abstract: As a series of experimental determinations of the thermal diffusivity of molten alkali halides, this paper describes measurements on five molten alkali metal chlorides (LiCl, NaCl, KCl, RbCl, and CsCl) in the temperature range up to 1440 K by the forced Rayleigh scattering method. K2Cr2O7 is employed as a dye substance to color the transparent molten salts. The accuracy is estimated to be ± 4 to ±11 % depending on the measured salts. In comparison with the present results converted into thermal conductivity, most of the previous experimental data obtained by steady-state methods show larger values, up to about five times, which may be due to the systematic error caused by the presence of convection and radiation. It is found that the thermal conductivity of these series of molten alkali metal chlorides decreases with increasing molecular weight, and their temperature coefficients are weakly negative.

Preparation of addition polymerization catalysts

Abstract: Metal complexes useful as components of addition polymerization catalysts are prepared by oxidizing Group 4 or Lanthanide metal containing complexes using an organic halide oxidizing agent in a unique one electron oxidation.

Materials chemistry communications. Preparation of monolithic metal oxide gels by a non-hydrolytic sol–gel process

Abstract: Non-hydrolytic condensation between halide and alkoxide metal precursors leads to oxide gels; thus, Al2O3 and TiO2 were successfully synthesized as monolithic gels.

Surface charge of alkali halide particles as determined by laser-Doppler electrophoresis

Abstract: Nonequilibrium electrophoretic-mobility measurements by laser-Doppler electrophoresis are reported for alkali halide particles. These measurements have been made for the first time and allow for the sign of the surface charge to be predicted for alkali halides in their saturated brines. In general, the results can be explained from the simplified lattice ion hydration theory; however, potassium chloride is, at least, one noteworthy exception. On the basis of this analysis, particle dispersion/aggregation behavior in saturated brines can be explained. Further, the nature of collector (surfactant) adsorption and the flotation behavior of the alkali halide salts from their saturated brines can now be described more accurately. 20 refs., 7 figs., 3 tabs.

Intramolecular Oxypalladation and Cross-Coupling of Acetylenic Alkoxides

Abstract: Stereodefined 2-alkylidenetetrahydrofurans and pyrans were synthesized by treatment of alkyl or aryl acetylenic alcohols with n-BuLi in THF at 0 o C followed by addition of a solution of 10 mol % of Pd(OAc) 2 or PdCl 2 and PPh 3 in THF and 1 equiv of an organic halide

Interfacially synthesized reverse osmosis membranes and processes for preparing the same

Abstract: Water permeable reverse osmosis membranes are prepared by interfacially polymerizing on a microporous support an essentially monomeric polyamine reactant having at least two amine functional groups per reactant molecule, and an essentially monomeric amine-reactive polyfunctional single ring cycloaliphatic acyl halide having fewer than six carbon atoms per ring and having on the average at least about 2.2 acyl halide groups per reactant molecule. The polymerization is preferably carried out in the presence of a monomeric amine salt, which increases the flux rate of the resulting membrane. In addition, an aromatic polyfunctional acyl halide may be used in conjunction with the cycloaliphatic acyl halide in order to increase salt rejection rates. Preferred cycloaliphatic acyl halides are 1-cis, 2-trans, 3-cis, 4-trans-cyclopentane tetracarboxylic acid chloride, 1-cis, 2-trans, 3-cis, 4-trans-cyclobutane tetracarboxylic acid chloride and 1-cis, 2-trans, 4-cis-cyclopentane tricarboxylic acid chloride. The preparation of novel alternating cis/trans isomers of cycloaliphatic polycarboxylic acid halides is carried out using metal salts of the all-cis polycarboxylic acids.

Structural studies on phenyl bismuth halides and halogenoanions

Abstract: Structural studies by X-ray crystallography have been carried out for a range of phenyl bismuth halides and halogenoanions. The complexes [BiPhBr2(thf)]1 and [BiPhI2(thf)]2(thf = tetrahydrofuran) form one-dimensional polymeric chains with a single asymmetrically-bridging halide between each pair of adjacent bismuth atoms. The co-ordination geometry around the bismuth centre is that of a square-based pyramid with the phenyl group in the apical position and two cis halides, a bridging halide from an adjacent monomer unit and a thf ligand in the basal plane. Addition of [NEt4]I to 2 affords the ionic species [NEt4]2[Bi2Ph2I6]·Et2O 3 which contains the discrete dimeric [Bi2Ph2I6]2– anion. This anion comprises two edge-shared square-based pyramids with an angle of 105.2° between the basal planes. As with 1 and 2, the phenyl group occupies the apical site with the basal sites around each bismuth occupied by two terminal and two bridging iodides. The complex [BiPh2Br(thf)]5 is monomeric and has an equatorially vacant trigonal-bipyramidal co-ordination geometry around the bismuth centre in which the phenyl groups occupy the equatorial sites and the bromine and thf ligand the axial sites. The structure of [PPh4][BiPh2Br2]6 contains monomeric [BiPh2Br2]– anions with a geometry similar to that found in 5. Comparisons are made, where appropriate, with related tellurium(IV) compounds, and the nature of the bonding in the complexes is discussed particularly with regard to the details of the secondary, intermolecular bonds observed in the structures of 1–3.

Electrical properties of the gold—aqueous solution interface

Abstract: The electrokinetic properties of gold particles dispersed in aqueous inorganic electrolyte solutions have been studied using the technique of microelectrophoresis. Results obtained for dispersions formed from vacuum-evaporated metal indicate that electrical charge development at the “pristine” surface of gold in contact with aqueous solutions arises from the presence of a surface oxide layer. The influence of halide ions on the electrokinetic properties of these particles is consistent with metal—halide interactions involving both ligand exchange and specific anion adsorption. Evidence has been obtained which indicates that in the case of dispersions formed by citrate reduction of chloroauric acid, strongly adsorbed citrate ions modify the metal surface and inhibit interactions with halide species.

Tandem SN2-Michael reactions for the preparation of simple five- and six-membered-ring nitrogen and sulfur heterocycles

Abstract: A one-pot tandem S N 2-Michael addition sequence has been developed for the preparation of five-membered- and six-membered-ring nitrogen and sulfur heterocycles from 6- or 7-halo-2-alkenoate esters. Nitrogen-containing rings are prepared by reaction of the ω-halo-2-alkenoate ester with a primary amine in the presence of triethylamine. The sulfur analogues are generated by thiourea displacement of the halide followed by base hydrolysis of the isotthiouronium salt. Yields are routinely in the 60-80% range. Experiments are described which elucidate the chronology of the reaction sequences

Method for producing a stereospecific polyolefin

Abstract: A method for producing a stereospecific polyolefin in the presence of a catalyst comprising a transition metal compound and an organometallic compound, wherein a catalyst system is used which comprises (A) a solid catalyst component prepared by reacting a homogeneous solution containing (i) at least one member selected from the group consisting of metal magnesium and a hydroxylated organic compound, and oxygen-containing organic compounds of magnesium, (ii) an oxygen-containing organic compound of aluminum and (iii) an oxygen-containing organic compound of titanium, with (iv) at least one aluminum halide compound to obtain a solid product, and further reacting to this solid product, (v) an electron-donative compound and (vi) a titanium halide compound, (B) at least one member selected from the group consisting of organometallic compounds of Groups IA, IIA, IIB, IIIB and IVB of the Periodic Table, and (C) an oxygen-containing organic compound of silicon which has no aromatic substituent and which has at least one hydrocarbon group containing a secondary or tertiary carbon directly bonded to a silicon atom.

F430 model chemistry. Mechanistic investigation of the reduction, coupling, and dehydrohalogenation of alkyl halides by the nickel(I) octaethylisobacteriochlorin anion

Abstract: The reactions of Ni I (OEiBC) - with alkyl halides and p-toluene sulfonates and with hydrogen atom and proton donors were investigated in a wide range of solvents. The ease of reduction of Ni II (OEiBC) by sodium amalgam and the stability of the Ni I (OEiBC) - generated was greater in more polar solvents.

Method and apparatus for dry etching

Abstract: PURPOSE:To accurately etch the fine pattern of a metal film with a silver layer at a high speed by impressing high frequency voltage to a gaseous halogen or a gaseous halogenated compound and the gas of a material to be a neutral ligand to make the mixed gas plasma CONSTITUTION:In a vacuum vessel 1 placed and arranged with a semiconducting wafer 9 provided with the metal film incorporating the silver layer and/or sliver alloy layer on a holder 7, the mixed gas of the gaseous halogen gas and/or the gaseous halogenting and the gas of material to be the neutral ligand or vaporized gas of an aluminum halide produced in a constant temp bath, is introduced As the above-mentioned halogen, F2, Cl2, etc, are exemplified and as the halogenated, compound HF, HCl, etc, are exemplified and as the material to be the neutral ligand, NH3, H2O, etc, are exemplified Successively, the inside of the vacuum vessel 1 is made to the prescribed vacuum condition with a vacuum pump 6 and the above-mentioned mixed gas is made to the plasma in the high frequency voltage impression through a power source 8 By this plasma, the metal complex of silver halide having high vaporizing pressure and the neutral ligand or sliver-aluminum halide is produced and dry- etching is efficiently applied to the metal film to form the fine pattern

Reduced temperature suppression of volatilization of photoexcited halogen reaction products from surface of silicon wafer

Abstract: Wafer surface degradation in a photoexcitation dry cleaning process, due to volatilization of surface halides that allows the exposed silicon surface to be further etched, is obviated by controlling the conditions of the process, specifically silicon wafer surface temperature, such that silicon reaction products that are formed on the surface of the wafer in the presence of the photoexcited disassociated halogen radicals do not volatilize The silicon wafer is placed upon a low temperature chuck When the halogen gas within the reaction chamber is irradiated with ultraviolet light, it produces disassociated halogen atoms that react with the surface of said silicon Irradiation of the halogen gas and the surface of the silicon wafer is controlled by an optical shutter, in order to limit the amount of ultraviolet radiation that strikes and is absorbed by the wafer The reduced temperature of the wafer prevents volatilization of a surface film containing halogen-contaminant compounds and halogen-silicon reaction products As a consequence, further reaction of the halogen reactant radicals with silicon underlying the surface film is effectively suppressed Thereafter, the surface film is removed from the surface of the wafer, for example by increasing its temperature in halogen free chamber at a reduced pressure, or by dissolving the film in a rinse solution, such as water