Catalysts nickel borides

HYDROGENATION CATALYSTS Bis-(pyridine)dimethylformamidcdichlororbo-dium borohydride. Iron pentacarbonyl. Lindlar catalyst. Nickel boride. Palladium-on-calcium carbonate. Rhodium-on-alumina. Rhodium-on-carbon. Ruthenium trichloride hydrate. Triton dodecacar-bonyL Tris(tiiplienylpho ine)chloto-... 

HYDROGENATION CATALYSTS Chloro-platinic acid-Triethyl silane. Lindlar catalyst. Nickel boride. Osmium-on-carbon. Palladium hydroxide. Tris(triphenylphos-phine)chlororhodium. 

Catalysts show remarkable product variation in hydrogenation of simple nitriles. Propionitrile, in neutral, nonreactive media, gives on hydrogenation over rhodium-on-carbon high yields of dipropylamine, whereas high yields of tripropylamine arise from palladium or platinum-catalyzed reductions (71). Parallel results were later found for butyronitrile (2S) and valeronitrile (74) but not for long-chain nitriles. Good yields of primary aliphatic amines can be obtained by use of cobalt, nickel, nickel boride, rhodium, or ruthenium in the presence of ammonia (4J 1,67,68,69). 

Methyl a-D-mannopyranoside was treated in succession with p-toluene-sulfonyl chloride, carbonyl chloride, and benzoyl chloride, and, without isolating the intermediates, there was obtained in 37% yield methyl 4-0-l enzoyl-2,3-O-carbony 1-6-0-(p-tolylsulfonyl ) -D-mannoside. The tos-yloxyl group of the latter was replaced by iodine, and hydrogenation of the 6-iodo derivative in the presence of a nickel boride catalyst gave methyl 4-0-benzoyl-2,3-0-carbonyl-6-deoxy- -D-mannoside. Treatment of the latter with hydrogen bromide in acetic acid gave crystalline 4-0-benzoyl-2,3-0-carbonyl-6-deoxy-a-D-mannosyl bromide (8) (16). The... 

Thiophenes can also be desulfurized to alkenes (RCH2CH=CHCH2R from 115) with a nickel boride catalyst prepared from nickel(II) chloride and NaBILj in methanol.It is possible to reduce just one SR group of a dithioacetal by treatment... 

Moreover, stable liquid systems made up of nanoparticles coated with a surfactant monolayer and dispersed in an apolar medium could be employed to catalyze reactions involving both apolar substrates (solubilized in the bulk solvent) and polar and amphiphilic substrates (preferentially encapsulated within the reversed micelles or located at the surfactant palisade layer) or could be used as antiwear additives for lubricants. For example, monodisperse nickel boride catalysts were prepared in water/CTAB/hexanol microemulsions and used directly as the catalysts of styrene hydrogenation [215]. 

In some cases it is necessary to hydrogenate allylic compounds to saturated molecules without hydrogenolysis. It was found that nickel boride is a good catalyst for this purpose.46... 

A catalyst that permits hydrogenation of an alkyne to an alkene is the nickel boride compound called P-2 catalyst. 

In ethanol nickel(II) acetate treated with NaBFLt produces a nearly colloidal black suspension63. Variation of the solvent in the preparation of the nickel catalyst results in an amorphous nickel boride catalyst67,68. This P-2 nickel catalyst is much more sensitive to the double-bond structure69,70. In the hydrogenation of the strained double bonds of nor-bomadienes, P-2 nickel shows high selectivity (95%) and low isomerization characteristics (equations 20 and 21). 

Another highly active non-pyrophoric nickel catalyst is prepared by reduction of nickel acetate in tetrahydrofuran by sodium hydride at 45° in the presence of tert-amyl alcohol (which acts as an activator). Such catalysts, referred to as Nic catalysts, compare with P nickel boride and are suitable for hydrogenations at room temperature and atmospheric pressure, and for partial reduction of acetylenes to civ-alkenes [49]. 

Hydrogenation using Raney nickel is carried out under mild conditions and gives cis alkenes from internal alkynes in yields ranging from 50 to 100% [356, 357, 358, 359, 360]. Half hydrogenation of alkynes was also achieved over nickel prepared by reduction of nickel acetate with sodium borohydride (P-2 nickel, nickel boride) [349,361,362] or by reduction with sodium hydride [49], or by reduction of nickel bromide with potassium-graphite [363]. Other catalysts are palladium on charcoal [364], on barium sulfate [365, 366], on... 

Monodispersed, 2- to 6-nm-dia- Particles, formed from their metal salts by meter nickel boride, cobalt boride, NaBH4 reduction, were used as catalysts, nickel-cobalt boride, and iron Micellar core size controlled particle sizes... 

Paul Buisson Joseph Ind. Eng. Chem. 1952,44, 1006 Brown Chem. Commun. 1969,952. J. Org. Chem. 1970, 35. 1900. For a review of reductions with nickel boride and related catalysts, sec Canem Osby Chem. Rev. 1986, 86. 

O-p-tolylsulfonyl-a-D-mannoside (39) in 37% yield. Treatment of (39) with sodium iodide in acetone gave the 6-iodo derivative (40), which underwent reduction with hydrogen in the presence of a nickel boride" catalyst" to give methyl 4-0-benzoyl-2,3-0 carbonyl-6-deoxy-o>-D-manno-side (41) in 95% yield. Reaction of (41) with hydrogen bromide in acetic acid effected replacement of the methoxyl group at C-l, affording crystalline... 

Unsaturated aldehydes.4 A nickel boride catalyst similar to P-2 nickel boride is obtained by reaction of NiCl2 and excess NaBH4 in C2H5OH. It effects selective hydrogenation of a,P-alkynal acetals to the (Z)-a,p-alkenal acetals. 

Palladium catalysts, 230 of alkyl silyl ethers to alkanes Nickel boride, 197 of alkyl sulfonates to alkanes Lithium triethylborohydride, 153 of alkynes to cis-alkenes... 

Arene(tricarbonyl)chromium complexes, 19 Nickel boride, 197 to trans-alkenes Chromium(II) sulfate, 84 of anhydrides to lactones Tetrachlorotris[bis(l,4-diphenyl-phosphine)butane]diruthenium, 288 of aromatic rings Palladium catalysts, 230 Raney nickel, 265 Sodium borohydride-1,3-Dicyano-benzene, 279 of aryl halides to arenes Palladium on carbon, 230 of benzyl ethers to alcohols Palladium catalysts, 230 of carboxylic acids to aldehydes Vilsmeier reagent, 341 of epoxides to alcohols Samarium(II) iodide, 270 Sodium hydride-Sodium /-amyloxide-Nickel(II) chloride, 281 Sodium hydride-Sodium /-amyloxide-Zinc chloride, 281 of esters to alcohols Sodium borohydride, 278 of imines and related compounds Arene(tricarbonyl)chromium complexes, 19... 

Benzaldehyde has been hydrogenated on Pd/C(l), Raney nickel and nickel boride (2) catalysts. Baltzly (Ref. 1) measured the rate of hydrogen pressure decrease as a function of time in a batch reactor. He found that the rate of reaction was zero order for both reactants at hydrogen pressures above 3 atm. and benzaldehyde concentrations above 1.0 gmol/1. The rate data was obtained at 22°C in various solvents. No measurements of the products and the benzaldehyde were reported. For the 3% Pd/C catalyst, the rate of reaction was 1.6 x 10 2 gmol/g.min, independent of the type of solvent. 

When one component of a bimetallic alloy is leached out, a finely divided metal powder of high surface area results. One of the oldest of these so-called skeletal metal catalysts is Raney nickel10,11. Nickel boride is a more recently developed hydrogenation catalyst prepared by the reduction of nickel salts with sodium borohydride12-14. Bimetallic catalysts are often used to achieve selective saturation of a double bond in bifunctional unsaturated systems, e.g. in dienes. Amorphous metal alloys, a newly developed class of metal catalysts15,16, have also been applied in the hydrogenation of alkenes and dienes. 

Nickel, either as a Raney catalyst or in the form of nickel boride, is also effective in the reduction of the C=0 bond. An increase in the catalytic activity can be brought about by metal promoters (chromium and molybdenum). Copper chromite may also be used. 

Ni-Gr I.1 This nickel catalyst reduces disubstituted alkynes to cis-alkenes the stereoselectivity is comparable to that observed with Lindlar catalyst or nickel boride (3, 208 -210 5,471-472). 

There have been a considerable number of papers reporting the properties of sulphur-resistant methanation catalysts, i.e., catalysts which can operate successfully in significant partial pressures of H2S. Most of these report work using catalysts containing vanadium, molybdenum, and such metals. However, attempts have been made to find nickel-based catalysts containing suitable additives to allow them to operate in such atmospheres. For example, Bartholomew and Uken115 have compared the deactivation behaviour of a range of nickel catalysts in 10 p.p.m. H2S. They found that nickel boride catalysts and Raney nickel materials deactivated more slowly than did unsupported nickel and alumina-supported nickel. They attributed this improvement to two factors ... 

---