Catalysis with nickel

Various amines were studied using 4-chlorobenzenethiol as the thiol reactant, as summarized in Table 6.7. The reaction is very selective for secondary aliphatic amines. The primary aliphatic amines and anilines failed to undergo this reaction (entries 6-12). 

This system can be rendered catalytic by the addition of an appropriate oxidant to regenerate the Ni(II) from Ni(0). It would be beneficial to use oxygen as the oxidant, so that HX can be recycled to produce H2O which would deter side-product formahon (Equation (6.11)). To test this possibility, experiments were run using catalyhc amounts of (PPh3)2NiBr2 and air as the oxidant (Table 6.8). The catalyhc formahon of the thiocarbamate is accompanied by compehtive 

10-diphenylphenanthrene can take place and a second alkyne insertion regenerates the Ni(0) complex 1. 

Ni-C bond of the coordinated biphenyl then occur. The regeneration of (dippe) Ni(CO)2 is accomplished by the displacement of fluorenone by CO. 

A recent publication has reported the coupling reaction between azohum salts and ethylene, catalyzed by zerovalent nickel complexes [48]. A combination of experiment and density functional theory (DFT) was used to show that the reaction proceeds via a redox mechanism. This redox mechanism involves the generation of Ni-carbene intermediates. 

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Insertion of carbon dioxide into olefin oxides gives olefin carbonates, and is an example of basic catalysis with nickel(O) complexes (example 14, Table XI). 

Arl — ArCOOHCarbonylation of Arl to form ArCOOH can be effected by catalysis with nickel cyanide and a phase-transfer catalyst, cetyltrimethylam-... 

When electron deficient alkenes are added to cyclopropene derivatives (74 equation 33) and (77 equation 34) in the presence of [Ni(COD)2], vinylcyclopropanes are formed in good yields. For example, dialkyl fumarate or maleate reacts with 3,3-dimethylcyclopropene in the presence of [Ni(COD)2] to give 2,3-bis(alkoxycarbonyl)-l-(2-methyl-l-propenyl)cyclopropanes (75), (76), (78) and (79), in which alkene stereochemistry is chiefly retained, in 50-73% yields. Reaction of methyl acrylate with 3,3-dimethylcyclopropene results in the formation of several products, while reaction of methyl acrylate with 3,3-diphenylcyclopropene gives vinylcyclopropane derivatives (80 equation 35) in 85% yield. Under similar conditions, methyl crotonate reacts with (74a) to give (82) in low yield (equation 36). Catalysis with nickel(0)/PR3, 2 [Ni(CO)4], 3 [Pd(DBA)2] or [Pd(DBA)2]/PlV33 gives mainly... 

As an unexpected result of our investigations on the arylation of amines, a new catalysis with nickel complexes was pointed out for the aminolysis of nitriles indeed, in the reaction of the p-bromobenzonitrile with the 4-phenylpyridine in the presence of catalytic amounts of NiBr2, in addition to the expected arylamine, the amide resulting from the aminolysis of the cyano group (and subsequent hydrolysis during the work-up) was isolated (eqn. 8). 

THE ROLE OE SUPRAMOLECULAR NANOSTRUCTURES EORMATION IN THE MECHANISMS OF HOMOGENOUS AND ENZYMATIC CATALYSIS WITH NICKEL OR IRON COMPLEXES... 

De Pasquale, R.J. Unusual Catalysis with Nickel (0) Complexes. J. Chem. Soc. Chem. Commun. 1973, 157-158. 

Nickel catalysts can be used instead of copper catalysts to promote the conjugate addition reaction, providing, in some cases, better results than the corresponding copper catalysts. In 2000, Yang et al. discovered a series of (li ,25, 3i )-3-mercaptocamphan-2-ol derivatives, which proved to be efficient ligands in the conjugate addition of ZnEt2 to chalcone upon catalysis with Ni(acac)2 (Scheme 2.29). 

Sulfonium ylides R2S=CR 2 [672,673] and metallated sulfones [674-676] can cyclopropanate simple alkenes upon catalysis with copper and nickel complexes (Table 3.6). Because of the increased nucleophilicity and basicity of these ylides, compared with diazoalkanes, these reagents are prone to numerous side-reactions,... 

Bicyclopropylidene (1) also reacts with activated alkenes under transition-metal catalysis. With electron-deficient alkenes under nickel(O) catalysis, the [2-1-2] cycloadduct 263 was the main component in the reaction mixture [2b, 150]. Under palladium(O) catalysis, formal [3-1-2] cycloaddition of electron-deficient (Scheme 60) as well as strained alkenes can be achieved exclusively... 

To sum up, the available data relative to oxygen adsorption or catalysis on nickel oxide show the existence of two types of chemisorbed oxygen, one of them being related to the ability of this oxide to accommodate excess oxygen. The evidence concerning this latter property will now be reviewed with emphasis on the defect structure of bulk nickel oxide. 

The application of perfluorous polyethers in biphasic catalysis was first described by Vogt (133), who also synthesized ligands based on hexafluor-opropene oxide oligomers to create metal complexes that are soluble in the perfluorous polyethers. The solvophobic properties of the fluorous solvent were successfully incorporated in the metal complexes catalytic oligomerization and polymerization reactions with nickel and cobalt complexes were demonstrated. 

These heterogeneous catalysis contain nickel, cobalt, molybdenum, tungsten, platinum, or palladium on acidic aluminum silicate or zeolite supports. As with reforming catalysts, the catalysts here are also believed to be... 

During interaction of the diazonium chloride, and the o-ethyl dithiocarbonate ( xan-thate ) solutions, care must be taken to ensure that the intermediate diazonium dithiocarbonate decomposes to 2-thiocresol as fast as it is formed [1]. This can be assured by presence of a trace of nickel in the solution to effect immediate catalytic decomposition. When the 2 solutions were mixed cold and then heated to effect decomposition, a violent explosion occurred [2]. Caution The experiments claimed to show catalysis by nickel appear to have been performed on diazotised anthranilic acid which is the only benzenediazonium system never known to give explosive intermediates with sulfur nucleophiles [3]. 

Recent work from Lipshutz [10] et al. even shows at least in CC-bond formations the replacement of the rather expensive palladium with nickel. Chloroarenes are coupled with organo zink compounds under nickel]0) catalysis. 

Palladium-catalyzed allylation reactions proceed with net retention of configuration that is the result of two inversions.118-120 132-135 Grignard reactions with nickel or copper catalysis proceed with net inversion.128 136-138... 

Zhang and Rusling [66] employed a stable, conductive, bicontinuous microemulsion of surfactant/oil/water as a medium for catalytic dechlorination of PCBs at about 1 mA cm-2 on Pb cathodes. The major products were biphenyl and its reduced alkylbenzene derivatives, which are much less toxic than PCBs. Zinc phthalocyanine provided better catalysis than nickel phthalocyanine tetrasulfonate. The current efficiency was about 20% for 4,4 -DCB and about 40% for the most heavily chlorinated PCB mixture. A nearly complete dechlorination of 100 mg of Aroclor 1260 with 60% Cl was achieved in 18 hr. Electrochemical dehalogenation was thus shown to be feasible in water-based surfactant media, providing a lower-cost, safer alternative to toxic organic solvents. 

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