Showing papers on "Nickel boride published in 1995"
TL;DR: The generalized susceptibility for rare-earth nickel boride carbides has been calculated using the normal-state electronic structure and Peaks in the susceptibility occur near wave vectors corresponding to those observed for the incommensurate spin density waves.
Abstract: The generalized susceptibility for rare-earth nickel boride carbides has been calculated using the normal-state electronic structure. Peaks in the susceptibility occur near wave vectors corresponding to those observed for the incommensurate spin density waves in ${\mathrm{HoNi}}_{2}$${\mathrm{B}}_{2}$C between approximately 4.7 and 6.0 K [A. I. Goldman et al., Phys. Rev. B 50, 9668 (1994)].
67 citations
TL;DR: In this paper, the selectivity of conjugated enones to the corresponding carbonyl compounds has been investigated in aqueous methanol under constant current at nickel boride, fractal nickel, and Raney nickel electrodes made of pressed powders.
Abstract: The selectivity of the electrocatalytic hydrogenation (ECH) of conjugated enones to the corresponding carbonyl compounds has been investigated in aqueous methanol under constant current at nickel boride, fractal nickel, and Raney nickel electrodes made of pressed powders. The influence of various parameters (water percentage, pH, concentration of substrate, and current density) on the selectivity of the carbon–carbon double bond hydrogenation was studied with cyclohex-2-en-1-one at nickel boride electrodes. Under given electrolysis conditions, fractal nickel electrodes were found to give the highest selectivity. The selectivity of the ECH of a variety of conjugated enones at fractal nickel electrodes was determined under electrolysis conditions that gave the best selectivity with cyclohexenone at nickel boride electrodes. Keywords: electrocatalytic hydrogenation, α,β-unsaturated ketones, selective hydrogenation, nickel based cathodes.
40 citations
TL;DR: In this article, a practical synthesis of epibatidine (1) was developed, which involved selective reduction of the 5,6 double bond of 7-(tert-butyloxy-carbonyl)-2-(2-chloro-5-pyridyl)-3-(phenylsulfonyl)7-azabicyclo[2.2.1]-heptane-2,5-diene using nickel boride.
30 citations
01 Dec 1995-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, solid state reaction induced by ball milling the elemental components has been investigated on Ni60B40 and Ni80B20 mixtures by means of transmission electron microscopy, X-ray diffraction and differential scanning calorimetry.
Abstract: Solid state reaction induced by ball milling the elemental components has been investigated on Ni60B40 and Ni80B20 mixtures by means of transmission electron microscopy, X-ray diffraction and differential scanning calorimetry. The time evolution of the reaction is similar in the two samples, although slower in Ni80B20. Reaction begins with the formation of o-Ni3B and of a disordered phase. The final products are nanocrystalline o-Ni3B and unreacted nickel in Ni80B20 and nanocrystalline t-Ni2B in Ni60B40. Different milling conditions, tested on the Ni60B40 sample, do not modify the path but affect the rate of the solid state reaction.
25 citations
14 citations
TL;DR: A nickel boride reagent, prepared in situ by the reaction of nickel chloride with sodium borohydride, has been used to dechlorinate chloro-olefinic compounds but chloroalkanes do not react as discussed by the authors.
Abstract: A nickel boride reagent, prepared in situ by the reaction of nickel chloride with sodium borohydride, has been used to hydrodechlorinate and hydrogenate chloroaromatic compounds. The same reagent can also dechlorinate chloro-olefinic compounds but chloroalkanes do not react. The reactions can be sustained by addition of hydrogen gas and the ratio of the aromatic to aliphatic hydrocarbons produced can be varied by addition of sodium hydroxide to the reaction mixture and by the duration of the reaction. The reactivity of polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), chlorobenzene and tetrachloroethylene have been studied. Capillary gas chromatography was used to follow the course of reactions and gas chromatography-mass spectroscopy (GC–MS) was used for product identification.
10 citations
5 citations
Patent•
25 Apr 1995
TL;DR: In this paper, the particles of titanium boride are intervened by the matrix layer of a mixed solid solution of nickel and/or chromium borides and titanium carbide.
Abstract: PURPOSE:To obtain sintered titanium boride ceramic having high density and high strength, maintaining the electric conductivity, corrosion resistance and thermal shock resistance of the ceramic. CONSTITUTION:The particles of titanium boride are intervened by the matrix layer of a mixed solid solution of nickel and/or chromium borides and titanium carbide. The titanium boride particles have the sizes in the range of 0.5 to 12mum, less than 25mum at the maximum, and do not directly contact with the adjacent particles and have more than 95% of relative density and more than 300MPa traverse strength. Since the content of titanium boride is more than 75wt.%, near the titanium boride particles, the particulate phase consisting of a mixed solid solution of titanium boride, nickel boride and chromium boride is formed and the spaces between the titanium boride particles are filled with the matrix layer fo a mixed solid solution of nickel and/or chromium boride and titanium boride.
3 citations
TL;DR: In this article, students measure the rate of hydrogenation of 4-vinylcyclohexene in the presence of an inexpensive, non-pyrophoric nickel boride (PI) catalyst prepared from nickel(II) acetate and sodium borohydride.
Abstract: Students measure the rate of hydrogenation of 4-vinylcyclohexene in the presence of an inexpensive, non-pyrophoric nickel boride (PI) catalyst prepared from nickel(II) acetate and sodium borohydride The vinyl group hydrogenates rapidly followed by the distinctly slower hydrogenation of the cyclohexene An atmospheric hydrogenation apparatus for the experiment is easily constructed from a 50-mL buret, a rubber thermometer adapter, a small pear-shaped flask, two short Pasteur pipets, two small syringe caps, a leveling bulb or separatory funnel, a small rubber stopper, and some Tygon tubing
3 citations
01 Jan 1995
TL;DR: In this article, a selective stepwise chemical degradation technique is applied to investigate alkanoic structural subunits in sulphur-rich macromolecular fractions (resins, asphaltenes, kerogens).
Abstract: A selective stepwise chemical degradation technique is applied to investigate alkanoic structural subunits in sulphur-rich macromolecular fractions (resins, asphaltenes, kerogens). Emphasis is given to the sulphur speciation in terms of intermolecular (thioether, thiodiether) and intramolecular (thiolane, thiophene) linking of structural subunits. The degradation sequence comprises two steps: (I) a desulphurization and (II) an oxidation of aromatic moieties liberating alkyl substituents as mono-and dicarboxylic acids. In this study, nickel boride is used for the desulphurization. The efficiency of the reagent is compared to other desulphurization reagents (Raney nickel, nickelocene/LiAlH4). The use of deuteriated nickel boride allows to label the site of former sulphur functionalities with deuterium. The reagent is tested on a set of reference compounds to elucidate the deuteriation pattern of various sites and types of sulphur bonds (e. g. thioether, thiolane, thiophene). Ruthenium tetroxide is used to release alkanoic substituents of aromatic subunits.
1 citations
TL;DR: An extremely active and colloidal nickel boride was prepared by using rare earth oxide as a support in the presence of polyethylene glycol (PEG) at room temperature which could act as a catalyst in the hydrogenation of olefinic compounds.
Abstract: An extremely active and colloidal nickel boride was prepared by using rare earth oxide as a support in the presence of polyethylene glycol (PEG) at room temperature which could act as a catalyst in the hydrogenation of olefinic compounds, such as 4-(4'-hydroxyphenyl)-3-buten-2-one
TL;DR: In this article, a practical synthesis of epibatidine (1) was developed, which involved selective reduction of the 5,6 double bond of 7-(tert-butyloxy-carbonyl)-2-(2-chloro-5-pyridyl)-3-(phenylsulfonyl)7-azabicyclo[2.2.1]-heptane-2,5-diene using nickel boride.
Abstract: A practical synthesis of epibatidine (1) was developed. The key step involved selective reduction of the 5,6-double bond of 7-(tert-butyloxy-carbonyl)-2-(2-chloro-5-pyridyl)-3-(phenylsulfonyl)-7-azabicyclo[2.2.1]-heptane-2,5-diene (4) using nickel boride.