Nickel acetylene compounds

Raney nickel deactivated with piperidine and zinc acetate has been used for semihydrogenation of acetylenic compounds. 

Nickel catalysts have been employed successfully for the semihydrogenation of various acetylenic compounds.1 Dupont was the first to study the hydrogenation of acetylenes using Raney Ni. Little or no change in the rate of hydrogenation on the uptake of 1 equiv of hydrogen was observed with the monosubstituted acetylenes, 1-heptyne... 

Nitta et al. compared the selectivity of copper, cobalt, and nickel borides (Cu-B, Co-B, and Ni-B) as well as Raney Ni and Ni-B modified with copper(II) chloride, in the partial hydrogenation of acetylenic compounds.82 The selectivity at 30% conversion... 

Several aliphatic diols and hydroxy ethers have been made by catalytic hydrogenation of the triple bond in the corresponding acetylenic compounds. Both platinum and nickel catalysts are used. 

Organic inhibitors in the nickel bath also influence the texture of nickel deposits. The inhibition effects are related to their molecular structure [6.69]. In the presence of brightners with unsaturated ethylenic or acetylenic compounds, the [110] texture is preferentially formed. With aryl-sulfonic compounds used as leveling agents, the [100] or [211] textures are favored. The modification of the crystal growth has been interpreted by an adsorption-hydrogenation-desorption model. The nature and the strength of a bond between a metallic surface and an adsorbed species depend on the... 

Finally, it merits to be highlighted that, despite the relatively large number of phosphonioacetylide complexes reported to date, the reactivity of these species remains almost unexplored, the scarce data presently available preventing any conclusion on the chemical behavior of the coordinated R3P C C framework. Thus, while the Ph iP C—f unit remained unaltered after treatment of the manganese complex 76 with bromine, an unusual behavior for acetylenic compounds that confirms the heterocumulenic [MnBr(CO)4(=C=CPPh3)] character of this complex [75], the in situ formed nickel derivative [NiCl2(C=CP( -Bu)3 P(n-Bu)3 ] readily reacted with an excess of dichloroethyne to afford 87 (Fig. 16) through a classical [2-I-2-I-2] alkyne-cyclotrimerization process [86]. 

Dicarbonyl compounds are also formed by the reaction of acetylenic compounds with nickel carbonylates 94>. 

The substitution of CO in metal carbonyls by olefinic and acetylenic compounds is one of the chief methods for preparing tt complexes of transition metals. Unfortunately this procedure fails almost completely when applied to nickel carbonyl, and this may be one of the reasons why until recently no tt complexes of nickel with olefinic or acetylenic ligands were known. The reasons for this behavior of nickel carbonyl will become clearer, if both its electronic structure and the mechanism of the ligand exchange reactions are considered. 

A bisallylnickel compound, which is a dimer of butadiene, is isolated by the reaction with nickel phosphine compounds as shown in eq. (19.48). It is also considered to be the intermediate of the compound shown in eq. (19.47). Further, it reacts with acetylene compounds at low temperatures, and subsequently reacts with carbon monoxide to give the ten-membered ring compound by elimination of nickel and simultaneous cyclization [91]. 

Reyiews.—Recent reviews on areas of acetylenic chemistry include synthetic routes to average-ring-size cycloalkynes, a study of the bonding in metal-acetylene complexes, transition-metal complexes of acetylene, intramolecular cyclization reactions with acetylenic bond participation, oligomerization of acetylenes induced by metals of the nickel triad, an article on the handling of acetylenic compounds, and a book on preparative acetylenic chemistry. ... 

The reaction of carbon dioxide with multiple bonded carbon derivatives proceeds in the presence of nickel (o) catalysts to give five-membered ring metallacycles, which on hydrolysis produce carboxylic acid derivatives. This derivatization of olefins and acetylene compounds is of considerable interest in synthetic organic chemistry. 

Catalysts suitable for selective hydrogenation of acetylenic compounds in cracked gas streams contain elements of group VI and VIII of the periodic table. An early catalyst was molybdenum sulfide supported on activated alumina (Key and Eastwood, 1946). This was followed by the development of cobalt molybdate and nickel based catalysts (Giaro, 1956 Barry, 1950). Modem catalysts for impure (sulfur-bearing) cracked gas streams typically contain nickel, cobalt, and chromium on a silica-alumina base (United Catalysts, 1993). 

Cuprous salts catalyze the oligomerization of acetylene to vinylacetylene and divinylacetylene (38). The former compound is the raw material for the production of chloroprene monomer and polymers derived from it. Nickel catalysts with the appropriate ligands smoothly convert acetylene to benzene (39) or 1,3,5,7-cyclooctatetraene (40—42). Polymer formation accompanies these transition-metal catalyzed syntheses. 

The direct combination of selenium and acetylene provides the most convenient source of selenophene (76JHC1319). Lesser amounts of many other compounds are formed concurrently and include 2- and 3-alkylselenophenes, benzo[6]selenophene and isomeric selenoloselenophenes (76CS(10)159). The commercial availability of thiophene makes comparable reactions of little interest for the obtention of the parent heterocycle in the laboratory. However, the reaction of substituted acetylenes with morpholinyl disulfide is of some synthetic value. The process, which appears to entail the initial formation of thionitroxyl radicals, converts phenylacetylene into a 3 1 mixture of 2,4- and 2,5-diphenylthiophene, methyl propiolate into dimethyl thiophene-2,5-dicarboxylate, and ethyl phenylpropiolate into diethyl 3,4-diphenylthiophene-2,5-dicarboxylate (Scheme 83a) (77TL3413). Dimethyl thiophene-2,4-dicarboxylate is obtained from methyl propiolate by treatment with dimethyl sulfoxide and thionyl chloride (Scheme 83b) (66CB1558). The rhodium carbonyl catalyzed carbonylation of alkynes in alcohols provides 5-alkoxy-2(5//)-furanones (Scheme 83c) (81CL993). The inclusion of ethylene provides 5-ethyl-2(5//)-furanones instead (82NKK242). The nickel acetate catalyzed addition of r-butyl isocyanide to alkynes provides access to 2-aminopyrroles (Scheme 83d) (70S593). 

When acetylene is heated with nickel cyanide, other Ni(II) or Ni(0) compounds, or... 

The regiochemistry of Al-H addition to unsymmetrically substituted alkynes can be significantly altered by the presence of a catalyst. This was first shown by Eisch and Foxton in the nickel-catalyzed hydroalumination of several disubstituted acetylenes [26, 32]. For example, the product of the uncatalyzed reaction of 1-phenyl-propyne (75) with BujAlH was exclusively ds-[3-methylstyrene (76). Quenching the intermediate organoaluminum compounds with DjO revealed a regioselectivity of 82 18. In the nickel-catalyzed reaction, cis-P-methylstyrene was also the major product (66%), but it was accompanied by 22% of n-propylbenzene (78) and 6% of (E,E)-2,3-dimethyl-l,4-diphenyl-l,3-butadiene (77). The selectivity of Al-H addition was again studied by deuterolytic workup a ratio of 76a 76b = 56 44 was found in this case. Hydroalumination of other unsymmetrical alkynes also showed a decrease in the regioselectivity in the presence of a nickel catalyst (Scheme 2-22). 

This hydride then may add an acetylene molecule to form the vinyl derivative. A carbon monoxide insertion will produce the acrylyl nickel compound which can yield acrylate esters by either of two routes. Direct alcoholysis of the acyl nickel group may take place, as occurs with acylcobalt compounds (42) or, an acyl halide (or other acyl derivative, e.g., acyl alkanoate) may be eliminated. Alcoholysis of the acyl halide would then complete the catalytic cycle (35). 

Again several alkyls add—molybdenum, chromium, iron, cobalt, nickel, the alkali metal alkyls and aluminum alkyls react. A tin alkoxide has recently been studied by Russian workers and found to add to acetylenes. Mercury chloride, of course, adds and two cobalt—cobalt bonded compounds add to acetylene. The second is questionable because it dissociates in solution and the reaction may be a radical reaction, one cobalt adding to each end of the triple bond. 

Addition of carbenes. Aryl acetylenes condense with the chlorinated oxocarbene 202 (35 hours at 100°) and give, through 1,3-cycloaddition, 3-substituted 4,5,6,7-tetrachloro-2-phenylbenzofurans (203).459 Compound 203 is readily dechlorinated (hydrogenation on Raney nickel in... 

Camphor- 10-sulfonic acid, 62 Unsaturated acetals or ketals Nickel boride, 197 (2R,4R)-Pentanediol, 237 Acetylenic carbonyl compounds a,p-Unsaturated acetylenic carbonyl compounds... 

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. 

Nickel catalysts for the syntheses of cyclic compounds were first successfully utilized by Reppe, who was able to prepare cyclooctatetraene from acetylene (65). This eight-membered ring synthesis, and also the preparation of cyclic products from strained olefins (e.g., bicycloheptene and norbornadiene) and acrylonitrile, have been adequately reviewed elsewhere (7) and will therefore not be considered further. A short account of the cyclization reactions of butadiene using nickel-containing catalysts has appeared previously in this series (/). The discovery of new synthetic possibilities and a deeper understanding of the mechanism of these reactions justify a more extensive treatment. 

Cocyclization of acetylene with isocyanides gives interesting new cyclic compounds 103, 116). The reaction patterns are generally similar to the cocyclization wdth carbon monoxide which is already known 103, 117). Low-valent nickel, palladium, or cobalt complexes are active in the following reactions 102, 103) for which intervention of acetylene complexes has been suggested ... 

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