Nickel catalyst, prepared from

Tillack and co-workers developed a rhodium-catalyzed asymmetric hydrosilylation of butadiyne 258 to afford allenylsilane 260 (Scheme 4.67) [106]. Among more than 30 chiral phosphine ligands investigated, the highest enantioselectivity was observed when the catalyst was prepared from [Rh(COD)Cl]2 (1 mol%) and (S,S)-PPM 259 (2 mol%) to afford the optically active allene 260 with 27% ee. Other metals such as Ir, Pd, Pt or Ni were less effective for example, a nickel catalyst prepared from NiCl2 and (R,R)-DIOP 251 or (S,S)-PPM 259 gave the allene 260 with 7-11% ee. 

Allyl cyanides can be added across alkynes in the presence of a nickel catalyst prepared from (COD)2Ni and (4-CF3CeH4)3P in situ to give functionalized di- or tri-substituted acrylonitriles in a highly stereoselective manner, presumably via n-allylnickel intermediates. a-Siloxyallyl cyanides also react at the y -position of a cyano group with both internal and terminal alkynes to give silyl enol ethers, which can be converted into the corresponding aldehydes or ketones upon hydrolysis.70... 

The compound of formula (5) is next subjected to selective hydrogenation to convert the acetylenic bond to an ethylenic bond. This can be readily accomplished by a number of different catalysts, such as a nickel catalyst prepared from a nickel salt and NaBFi4, Lindlar catalyst, or 5% palladium on barium sulfate in the presence of qunioline. The reaction was run at one atmosphere. Analyses by nuclear magnetic resonance and vapor phase chromatography showed the correct structure in good quantity. The product obtained was 3,7,ll,15-tetramethylhexadeca-2,5-dien-l-acetate (6), a C2o dienolacetate. 

Molina, R., and G. Poncelet, a-Alumina-Supported Nickel Catalysts Prepared from Nickel Acetylacetonate A TPR Study, J. Catal. 173,257-67 (1998). 

Fonseca, A. and Assaf, E.M. Production of the hydrogen by methane steam reforming over nickel catalysts prepared from hydrotalcite precursors. Journal of Power Sources, 2005, 142 (1-2), 154. 

Modified nickel catalysts were prepared from the various nickel sources (Table 1). In the case of the modified nickel catalysts prepared from NiO, e.d. ability of the catalyst depended on the NiO manufacturers. These phenomena were also observed for the e.d. hydrogenation of methyl acetoacetate (MAA) [6]. Since the method of the NiO preparation presumably affect the percentage of crystallite part of reduced Ni, the types of NiO would reflect the e.d. ability of the catalyst. On the other hand, fine nickel powder (FNiP) gave the e.d. catalyst... 

The discovery by Sabatier (1) of the reducing power of finely divided nickel, although unsuccessful in the reduction of pyridine to piperidine, led to the investigation of other nickel catalysts (prepared from nickel salts or oxides) for the same purpose. The development of Raney nickel catalyst (2) gave to the chemist a more active form of this metal. Its activity in the hydrogenation of the pyridine ring was first studied by Adkins (3) and his co-workers at the University of Wisconsin. Since this investigation, it has enjoyed wide use in the catalytic reduction of many pyridines. 

Couplings. A nickel catalyst prepared from reduction of (dppf)NiCl2 with BuLi has been employed to synthesize aiylalkenes by coupling arylborortic acids with enolphosphates. ... 

Tai, A., Kikukawa, T., Sugimura, T., Inoue, Y., Abe, S., Osawa, T., and Harada, T. (1994) An improved asymmetrically modified nickel catalyst prepared from ultrasonicated Raney nickel, Bull Chem. Soc. Jpn. 67, 2473 -2477. 

Osawa, T., Mita, S., Iwai, A., Miyazaki, T., Takayasu, O., Harada, T., and Matsuura, I. (1997) Enantio-differentiating hydrogenation of methyl acetoacetate over asymmetrically modified supported nickel catalyst prepared from nickel acetoacetonate, Chem. Lett. 1131-1132. 

In the hydrogenation of fatty oils such as cottonseed or peanut oil, it is often desirable to saturate only one double bond of the doubly unsaturated esters present. If such hydrogenations are carried out in the presence of a nickel catalyst containing even traces of nickel sulfide, an isomerization takes place so that the product contains isooleates (elaidates). Paterson (14) observed that this so-called elaidinization does not take place in the presence of nickel catalysts free of sulfur. Bailey, Fuege, and Smith (15) found that a nickel catalyst prepared from nickel sulfate catalyzed elaidinization." Ziels and Schmidt (16) recom-... 

Alkenyl-alkenyl cross-coupling. Baba and Negishi have prepared a catalyst from this Pd(II) complex and 2 equiv. of diisobutylaluminum hydride that promotes this coupling reaction. Tetrakis(triphenylphosphine)palladium(0) is inactive, as is material prepared in situ from palladium chloride, triphenylphos-phine and HAKr-CtHg) . A nickel catalyst prepared from Ni(acac)2, PfCnHsja, and diisobutylaluminum hydride is somewhat less efficient. The coupling Involves (E)-alkenylalanes (4, 158, 159) and alkenyl halides. The products are (E,E)- and (E,Z)-dienes. 

Physicochemical properties (metallic surface area, total surface area) of Raney Nickel catalysts prepared from well defined precursor alloys were related to the metallurgical structures of these alloys. The microstructure of the catalysts was correlated with the physicochemical characteristics and their activities for hydrogenation of acetophenone in the liquid phase. 

Yields obtained from catalyst prepared from 125 gm of aluminum-nickel alloy. In xylene as solvent. 

Among the J ,J -DBFOX/Ph-transition(II) metal complex catalysts examined in nitrone cydoadditions, the anhydrous J ,J -DBFOX/Ph complex catalyst prepared from Ni(C104)2 or Fe(C104)2 provided equally excellent results. For example, in the presence of 10 mol% of the anhydrous nickel(II) complex catalyst R,R-DBFOX/Ph-Ni(C104)2, which was prepared in-situ from J ,J -DBFOX/Ph ligand, NiBr2, and 2 equimolar amounts of AgC104 in dichloromethane, the reaction of 3-crotonoyl-2-oxazolidinone with N-benzylidenemethylamine N-oxide at room temperature produced the 3,4-trans-isoxazolidine (63% yield) in near perfect endo selectivity (endo/exo=99 l) and enantioselectivity in favor for the 3S,4J ,5S enantiomer (>99% ee for the endo isomer. Scheme 7.21). The copper(II) perchlorate complex showed no catalytic activity, however, whereas the ytterbium(III) triflate complex led to the formation of racemic cycloadducts. 

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... 

Evidence has been collected over the years which strongly indicates that the active species in the oligomerization reactions are nickel-hydride and nickel-alkyl complexes. [This is not necessarily true for catalysts prepared from nickel(II) compounds and organoaluminum compounds having low Lewis acidity, e.g., (C2H5)2A10C2H5 (44).] The majority of the evidence is circumstantial and is discussed below. 

Less clear is the sequence which leads to the formation of the active species in the case of catalysts prepared from zero-valent nickel complexes and aluminum halides or alkylaluminum halides (method C2). The catalytic properties of these systems, however—in particular, the influence of phosphines (76)—leaves no doubt that the active species is also of the HNiY type discussed above. In this connection, a recent electron spin resonance report that nickel(I) species are formed in the reaction of COD2Ni with AlBr3 (83 ), and the disproportionation of Ni(I) to Ni(II) and Ni(0) in the presence of Lewis acids (69) should be mentioned. 

A nickel-chromium catalyst prepared from chromous chloride and (p-diphenylphos-phinopolystyrene)nickel dichloride mediates the ring-closure of the ene-allene 236 (R = H) to a mixture of 3.4 parts of 237 and 1 part of 238 (equation 120)121. An analogous reaction of the t-butyldimethylsilyl ether of 236 yields solely the (E)-isomer 237 (R = t-BuMeaSi). Cyclization of the ene-allene 239 affords the perhydroindane 240 in 72%... 

In the presence of a large excess of cyanide, the catalyst prepared from [Ni(COD)2] and TPPTS was also active in the hydrocyanation of allylbenzene however, at low cyanide/nickel ratios isomerization to propenylbenzene became the main reaction path (Scheme 9.9) [5]. 

The reaction of 1-phenylethyl-, 2-octyl-, and 2-butyl-magnesium chloride (36a, b, c) with vinyl bromide (37a), (E)-p-bromostyrene (37b), 2-bromopropene (37c), and bromobenzene (37d) was carried out in the presence of 0.5 mol- % of a nickel catalyst prepared in situ from nickel chloride and the chiral ligand (35). 

Pipendine. the hydrogenation product of pyridine, is used as an intermediate for drugs and for making rubber-vulcanization accelerators, e.g., piperidinium pentamechylenedithiocarbamate (also known as Accelerator 552 ). On a commercial scale, piperidine (hexahydropyridine) is prepared by the catalytic hydrogenation of pyridine, e.g., with nickel catalysts at from 68 to 136 atmospheres pressure and at l50-20C,c,C. or under milder conditions with noble-metal catalysts. Pyridine derivatives can be similarly reduced to substitute piperidines. See formulas below. 

While hydrosilylation of imines is known to be effected by rhodium catalysts3, nickel catalysts prepared in situ from Ni(0Ac)2 4H20 and thiosemicarbazones are also found to promote the reactions of iV-substituted imines with HSiEt3 in dry DMSO at 35 °C, giving the corresponding secondary amines in excellent yields after basic work-up (equation 77)185. 

It was mentioned in Section 3.3.4 that alkenes react with H2 on the surface of elemental Pd or elemental Pt to form alkanes. Similar hydrogenations occasionally also can be accomplished using Raney nickel as a catalyst. Raney nickel is prepared from a 1 1 Ni/Al alloy and aqueous KOH. 

Nickel boride prepared from Nil2 and two equivalents of LiBH4 [42] was utilized as an oxazaborolidine catalyst support (Scheme 4) [43]. Reaction of nickel boride with 0.1 equivalents of chiral amino alcohol in THF at room temperature gave the anchored catalyst 6, which produced chiral alcohols in optical yields of up to 95%, and which furthermore showed higher activity as regards the reduction of acetophenone derivatives than that of the corresponding homogene-... 

The thermal treatment is one of the factors which controls the properties of the final catalyst [56]. The total surface area (in the range between 100 and 300m2g l) decreases with increasing reduction temperature however, the nickel surface area (typically 20-50 m2g l) increases which is probably due to a higher degree of reduction. The best precursor with respect to a high surface area is the hydroxycarbonate. The surface areas of catalysts prepared from hydroxy-chlorides and nitrates are smaller by about a factor of two. Nickel particle sizes are in the order of 5nm for such catalysts. 

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