Showing papers on "Nickel boride published in 2000"
TL;DR: In this paper, a root-growth mechanism is proposed for the catalyzed process of growing multiwalled BN nanotubes from nickel boride catalyst particles by chemical vapor deposition at 1000−1100 °C using borazine, B3N3H6, as the precursor.
Abstract: Multiwalled BN nanotubes are grown from nickel boride catalyst particles by chemical vapor deposition at 1000−1100 °C using borazine, B3N3H6, as the precursor. This precursor is generated in situ from molten salt that forms from mixtures of (NH4)2SO4, NaBH4, and Co3O4 at 300−400 °C. The BN nanotubes have concentric-tube structures, are free of internal closures, have crystalline walls, and exhibit lengths of up to ∼5 μm. The nanotubes often possess bulbous, flag-like, or club-like tip closures. A root-growth mechanism is proposed for the catalyzed process.
371 citations
TL;DR: In this article, the secondary amine dimers were found to be the major products under normal conditions, and the addition of a suitable trapping agent, such as di-tert-butyl dicarbonate, allowed the isolation of the protected primary amines.
66 citations
TL;DR: In this paper, the secondary amines of aldehydes and ketones with primary amines were obtained in the presence of in situ generated nickel boride, where the primary amine was replaced by a secondary amine.
Abstract: Reactions of aromatic aldehydes and ketones with primary amines give the corresponding secondary amines in the presence of in situ generated nickel boride.
45 citations
TL;DR: In this article, the authors investigated the failure mechanism of activated-diffusion-brazed (ADB) joints in IN-738 plate with two brazing alloys: Nicrobraz 150 and DF4B.
Abstract: The investigation of mechanical properties and failure mechanism of activated-diffusion-brazed (ADB) joints in IN-738 plate were conducted. Joints of this type, which had wide clearance, were formed using the brazing alloys Nicrobraz 150 and DF4B. The microstructural characterization showed that chromium borides with a blocky morphology were present in joints associated with the two brazing alloys. A major difference in matrix phase chemistry was observed, however, for the two brazing alloys, e.g., an Ni-B eutectic phase was observed in Nicrobraz 150, but DF4B exhibited a coarsened gamma prime (γ) phase and an absence of a nickel boride matrix phase. Results of tensile test showed that ADB specimens using DF4B brazing alloy exhibited 95% nominal tensile strength of IN-738 base materials. Fracture cracks in the joint area were initiated and confined to dispersed chromium boride sites. However, tensile test of ADB specimens using Nicrobraz 150 showed poor tensile properties at all testing temperatures, and their fractures were initiated at a brittle nickel boride site and propagated along the weak-bonded interface between the Ni-B eutectic phase and base materials.
26 citations
TL;DR: In this article, a new example of heterogenization of a homogeneous catalyst by anchoring the chiral molecule to nickel boride was reported, and the enantioselectivity in the reduction of acetophenone reaches that reported under homogeneous conditions.
Abstract: A new example of heterogenization of a homogeneous catalyst by anchoring the chiral molecule to nickel boride is reported. The enantioselectivity in the reduction of acetophenone reaches that reported under homogeneous conditions.
10 citations
TL;DR: A naturally occurring drimanic sesquiterpenic lactone, isodrimenin, was synthesized from drim-8-en-7-one (1) as discussed by the authors.
Abstract: A naturally occurring drimanic sesquiterpenic lactone, isodrimenin, was synthesized from drim-8-en-7-one (1). Compound1 was converted to the known 11,12-dihydroxydrim-8-en-7-one, which was oxidized with PCC to give 7-oxoisodrimenin. The thioketal of the latter compound was reduced with nickel boride or Raney nickel to give the target isodrimenin.
3 citations
2 citations
TL;DR: In this paper, a variety of substituted acetophenones can be reduced with high enantioselectivity by using borane and the heterogeneous catalyst derived from the reaction of (1 S,2 R )-(+)-2-amino-1,2-diphenylethanol with nickel-boride nanoparticles.
Abstract: A variety of substituted acetophenones can be reduced with high enantioselectivity by using borane and the heterogeneous catalyst derived from the reaction of (1 S ,2 R )-(+)-2-amino-1,2-diphenylethanol with nickel-boride nanoparticles.
2 citations
TL;DR: In this paper, a root-growth mechanism is proposed for the catalyzed process of growing multiwalled BN nanotubes from nickel boride catalyst particles by chemical vapor deposition at 1000−1100 °C using borazine, B3N3H6, as the precursor.
Abstract: Multiwalled BN nanotubes are grown from nickel boride catalyst particles by chemical vapor deposition at 1000−1100 °C using borazine, B3N3H6, as the precursor. This precursor is generated in situ from molten salt that forms from mixtures of (NH4)2SO4, NaBH4, and Co3O4 at 300−400 °C. The BN nanotubes have concentric-tube structures, are free of internal closures, have crystalline walls, and exhibit lengths of up to ∼5 μm. The nanotubes often possess bulbous, flag-like, or club-like tip closures. A root-growth mechanism is proposed for the catalyzed process.
1 citations
TL;DR: In this article, the secondary amines of aldehydes and ketones with primary amines were obtained in the presence of in situ generated nickel boride, where the primary amine was replaced by a secondary amine.
Abstract: Reactions of aromatic aldehydes and ketones with primary amines give the corresponding secondary amines in the presence of in situ generated nickel boride.
1 citations
TL;DR: A naturally occurring drimanic sesquiterpenic lactone, isodrimenin, was synthesized from drim-8-en-7-one (1).
Abstract: A naturally occurring drimanic sesquiterpenic lactone, isodrimenin, was synthesized from drim-8-en-7-one (1). Compound1 was converted to the known 11,12-dihydroxydrim-8-en-7-one, which was oxidized with PCC to give 7-oxoisodrimenin. The thioketal of the latter compound was reduced with nickel boride or Raney nickel to give the target isodrimenin.
TL;DR: In this paper, a new example of heterogenization of a homogeneous catalyst by anchoring the chiral molecule to nickel boride was reported, and the enantioselectivity in the reduction of acetophenone reaches that reported under homogeneous conditions.
Abstract: A new example of heterogenization of a homogeneous catalyst by anchoring the chiral molecule to nickel boride is reported. The enantioselectivity in the reduction of acetophenone reaches that reported under homogeneous conditions.