Carbon monoxide nickel carbonyl formation

Ma.nufa.cture. Nickel carbonyl can be prepared by the direct combination of carbon monoxide and metallic nickel (77). The presence of sulfur, the surface area, and the surface activity of the nickel affect the formation of nickel carbonyl (78). The thermodynamics of formation and reaction are documented (79). Two commercial processes are used for large-scale production (80). An atmospheric method, whereby carbon monoxide is passed over nickel sulfide and freshly reduced nickel metal, is used in the United Kingdom to produce pure nickel carbonyl (81). The second method, used in Canada, involves high pressure CO in the formation of iron and nickel carbonyls the two are separated by distillation (81). Very high pressure CO is required for the formation of cobalt carbonyl and a method has been described where the mixed carbonyls are scmbbed with ammonia or an amine and the cobalt is extracted as the ammine carbonyl (82). A discontinued commercial process in the United States involved the reaction of carbon monoxide with nickel sulfate solution. 

According to the free energy change associated with the pertinent reaction, nickel will form nickel tetracarbonyl at low temperatures, and this carbonyl will become unstable and revert back to nickel and carbon monoxide at moderate temperatures. The Mond process for refining nickel is based on these features. In this process, impure nickel is exposed to carbon monoxide gas at 50 °C, whereby volatile nickel tetracarbonyl (Ni(CO)4) forms. No impurity present in the crude nickel reacts with carbon monoxide. Since formation of the... 

Catalytic processes based on the use of electrogenerated nickel(O) bipyridine complexes have been a prominent theme in the laboratories of Nedelec, Perichon, and Troupel some of the more recent work has involved the following (1) cross-coupling of aryl halides with ethyl chloroacetate [143], with activated olefins [144], and with activated alkyl halides [145], (2) coupling of organic halides with carbon monoxide to form ketones [146], (3) coupling of a-chloroketones with aryl halides to give O -arylated ketones [147], and (4) formation of ketones via reduction of a mixture of a benzyl or alkyl halide with a metal carbonyl [148]. 

In the case of phosphine, especially tri-n-butyl and triphenyl phosphines, an active phosphine complex is formed in the reaction medium via reaction with nickel carbonyl. This complex is a very active species provided that the optimum concentration of phosphine is used. Low phosphine concentration results in a loss of the effective nickel concentration through the formation of nickel tetra-carbonyl, nickel metal or nickel iodide. The absolute concentration of phosphine is less important than the P/Ni ratio. In addition to form the stable Ni-P catalyst, the phosphine has to compete with other ligands in the reaction mixture for nickel. With high carbon monoxide partial pressure, there is more CO in solution to compete with phosphine favoring the formation of the carbonyl, which is inactive under the reaction conditions. Hence with high carbon mon-... 

In addition to the successful reductive carbonylation systems utilizing the rhodium or palladium catalysts described above, a nonnoble metal system has been developed (27). When methyl acetate or dimethyl ether was treated with carbon monoxide and hydrogen in the presence of an iodide compound, a trivalent phosphorous or nitrogen promoter, and a nickel-molybdenum or nickel-tungsten catalyst, EDA was formed. The catalytst is generated in the reaction mixture by addition of appropriate metallic complexes, such as 5 1 combination of bis(triphenylphosphine)-nickel dicarbonyl to molybdenum carbonyl. These same catalyst systems have proven effective as a rhodium replacement in methyl acetate carbonylations (28). Though the rates of EDA formation are slower than with the noble metals, the major advantage is the relative inexpense of catalytic materials. Chemistry virtually identical to noble-metal catalysis probably occurs since reaction profiles are very similar by products include acetic anhydride, acetaldehyde, and methane, with ethanol in trace quantities. 

Knowing all these facts, especially the difficult access to fluorophosphines and the poor donating abilities of phosphorus trifluoride (5, 6), we decided to use another approach, which readily led to a number of coordination compounds with fluorophosphine ligands—namely, the fluorination of chlorophosphines already coordinated to the transition metal, where the 3s electrons of phosphorus are blocked by the complex formation. There was no reaction between elemental nickel and phosphorus trifluoride, even under extreme conditions, whereas the exchange of carbon monoxide in nickel carbonyl upon interaction with phosphorus trifluoride proceeded very slowly and even after 100 hours interaction did not lead to a well defined product (5,6). 

Although nickel carbonyl is intensely poisonous, it is used in the Mond process for the refinement of nickel (see Section 16.3). Complex formation is also responsible for carbon monoxide s toxicity it attaches more strongly than oxygen to the iron in hemoglobin and prevents it from accepting oxygen from the air in the lungs. As a result, the victim suffocates. 

A second example of metal transport by single-component gas involves the formation of metal carbonyls that are unstable in carbon monoxide. Shen et al. (72) discovered that supported nickel particles are not stable in carbon monoxide. Under certain conditions, CO combines with the metal in the particles to form volatile metal carbonyls, such as nickel carbonyl. These volatile species carry the metal out of the reactor, resulting in a rapid net loss of metal. In some cases, metal is not carried out of the reactor, but new metal particles form at pore mouths, blocking them and effectively deactivating the catalyst. 

Nickel carbonyl is the more widely known catalyst for the carboxylation reaction dicobalt octacarbonyl has the disadvantage of giving side reactions (15). Dicobalt octacarbonyl has been used in the presence of tributyl phosphine for the reaction of ethylene, carbon monoxide, water, and ethanol. Besides ethyl acetate, acetaldehyde and diethyl ketone were found (136). Hydrogen has been found to increase the rate of reaction (78), presumably by the formation of cobalt hydrocarbonyl. However, this can lead to the formation of aldehydes, as in the reaction of acetyl bromide when an 89.4% yield of aldehyde was obtained in spite of the presence of water (95). 

Eventually we formed carbonyls in the liquid phase by redox disproportionation of nickel and cobalt derivatives of organic thioacids. In the reaction between nickel(II) dithiobenzoate and carbon monoxide in the presence of HS ion we assumed the formation of a sulfur-bridged nickel(IV) complex (VII, 32). More recent investigations (84), however, have shown that half the nickel appears as a monomeric nickel(II) complex of the same empirical formulation, formed by insertion of a sulfur atom in the dithio ligand, the other half of the nickel being reduced to nickel(O) by the sulfide. 

In regard to the second question raised about the possible mobility of nickel induced by the formation of nickel carbonyl during the CO chemisorption measurements, it is considered well established that the initial contact with CO after hydrogen reduction provides a reliable measure of the initial state of dispersion of the reduced nickel metal. The procedure used was evaluated in considerable detail (Ref. 10). It was pointed out in discussion of this evaluation that nickel displacement by carbonyl formation might occur upon heating and desorption of the chemisorbed carbon monoxide upon completion of the initial CO chemisorption measurement. 

The formation of nickel and iron carbonyls can take place in the presence of gaseous carbon monoxide in contact with metallic nickel or iron or their sulphides. The thermodynamics favor this reaction at low temperatures so the formation takes place during gas cooling. The consequences of any metal carbonyl slip into the gas treatment units depend very much on the treatment scheme, since any subsequent reheating (e.g., for a CO Shift) will tend to decompose the carbonyls back to the metals or their sulfides. 

Hydrocarboxylation is the formal addition of hydrogen and a carboxylic group to double or triple bonds to form carboxylic acids or their derivatives. It is achieved by transition metal catalyzed conversion of unsaturated substrates with carbon monoxide in the presence of water, alcohols, or other acidic reagents. Ester formation is also called hydroesterification or hydrocarb(o)alkoxylation . The transition metal catalyst precursors are nickel, iron or cobalt carbonyls or salts of nickel, iron, cobalt, rhodium, palladium, platinum, or other metals4 5. 

Metal Catalysts describes a number of asymmetric catalytic reactions, while nucleophilic activation of carbon monoxide and the application of metal carbonyl catalyzed water-gas shift (WGS) and related reactions to homogeneous catalysis have also been reviewed. A review on transition metal catalyzed carbonylations covers the year 1986. Reductions using ammonium formate as the reducing agent in the presence of homogeneous and heterogeneous nickel and palladium catalysts have been the subject of a recent survey. 

Preliminary results of the reaction between vanadium(iii)-tetrasulpho-phthalocyanine complex with oxygen have been reported these data were compared with those obtained for the corresponding reaction of the hexa-aquo complex ion. The oxidation of methyl ethyl ketone by oxygen in the presence of Mn"-phenanthroline complexes has been studied Mn " complexes were detected as intermediates in the reaction and the enolic form of the ketone hydroperoxide decomposed in a free-radical mechanism. In the oxidation of 1,3,5-trimethylcyclohexane, transition-metal [Cu", Co", Ni", and Fe"] laurates act as catalysts and whereas in the absence of these complexes there is pronounced hydroperoxide formation, this falls to a low stationary concentration in the presence of these species, the assumption being made that a metal-hydroperoxide complex is the initiator in the radical reaction. In the case of nickel, the presence of such hydroperoxides is considered to stabilise the Ni"02 complex. Ruthenium(i) chloride complexes in dimethylacetamide are active hydrogenation catalysts for olefinic substrates but in the presence of oxygen, the metal ion is oxidised to ruthenium(m), the reaction proceeding stoicheiometrically. Rhodium(i) carbonyl halides have also been shown to catalyse the oxidation of carbon monoxide to carbon dioxide under acidic conditions ... 

There has been a review of palladium-catalysed carbonylative coupling reactions of aryl halides with carbon nucleophiles in the presence of carbon monoxide. It has been shown that rhodium is an efficient catalyst for the homocoupling reaction of arylzinc compounds in the presence of 1 atm of carbon monoxide to give diaryl ketones. Under similar conditions, palladium and nickel catalysts yield biaryls. The beneficial catalysis by rhodium is likely to derive from the ease of migration of the aryl ligand to carbon monoxide in the rhodium(III) intermediate. A rhodium catalyst has also been used in the formation of indole-3-carboxylates by reaction of indoles with alcohols in the presence of carbon monoxide. The catalytic cycle. Scheme 5, is likely to involve metallation of the indole at the 3-position, followed... 

In addition, reductive elimination of palladium and nickel complexes to form esters (Equations 8.67 and 8.68), amides, and tiiioesters has been reported. -" The reductive eliminations of esters and amides were observed during mechanistic studies on the palladium-catalyzed formation of esters and amides from aryl halides, carbon monoxide, and alcohols or amines. This catalytic process is presented in Qiapter 17 (carbonylation processes). The reductive elimination of thioesters from nickel complexes were studied, in part, to understand the C-S bond-forming process of acetyl coenzyme A synthase. Prior to this work, an iron-mediated synthesis of p-lactams had been reported that appears to occur by reductive elimination to form the amide C-N bond of the lactam. ... 

Metallic nickel prepared by reduction of its compounds readily reacts with carbon monoxide to give Ni(CO)4 (Table 2.27). Many other metals (Fe, Co, Rh, and Re) may also react with CO however, the rate of formation of the carbonyl is slow, and the process must be carried out under forcing conditions. 

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