Cobalt , formation

Hi) Cobalt formate. There is evidence that the kinetics of decomposition of cobalt formate [1026,1027] are similar to those of the nickel salt, considered in some detail below. A significant point of difference, however, is that metal production during reaction of the former is preceded by formation of cobalt oxides [1028]. 

The olefin is then hydroformylated at low temperatures (90°-120°C) to yield 72-80% of linear aldehydes. The catalyst is recovered by mixing the product with air in an aqueous solution of cobalt formate. 

Step 4 Decobaltation of the Reaction Product. The product of the hydroformylation reactor containing the catalyst as a mixture of cobalt carbonyl hydride and dicobalt octacarbonyl is fed to the decobaiting section. Mixing the product at 120 °C and 10 atm with a dilute formic acid/ cobalt formate solution in the presence of air decomposes the catalyst (Reaction 9) (12). 

The only claim for the production of a metallocarboxylic acid from the insertion of C02 into a metal-hydrogen bond in the opposite sense is based on the reaction of C02 with [HCo(N2)(PPh3)3] (108, 136). The metallocarboxylic acid is said to be implicated since treatment of the product in benzene solution with Mel followed by methanolic BF3 yielded a considerable amount of methyl acetate as well as methyl formate derived from the cobalt formate complex. Metallocarboxylic acid species formed by attack of H20 or OH- on a coordinated carbonyl are considered in the section on CO oxidation. 

The workers at the Bureau of Mines performed a series of three experiments at 185° using reduced cobalt metal and butyraldehyde as a substrate (Wender, Orchin, and Storch, 10). The catalyst was prepared fresh in each of the three experiments by treating cobaltous formate in cyclohexane with hydrogen at 185° for 2 hours. An initial partial pressure of 2000 p.s.i. of hydrogen was used in each experiment and the partial pressure of carbon monoxide was varied. 

When carbon dioxide was bubbled througlt a solution of the cobalt-nitrogen complex CoHN>(PPhj)s, a cobalt-formate complex and the carbonyl complex Co(CO)(PPhj)3 were isolated (66], and treatment of the nickel complex [CpNi(PPh3)MgBr] with carbon dioxide in the presence of added magnesium bromide led to the nickel carbonyl complex (PPh3)jNi(CO)2. Possible intermediates are shown in F.quation (57). 

The primary quantiun eflBciencies for cobaltous formation were evaluated as 0.73 for 313 nifi, 0.69 for 365 mjuL (this is smaller than the value obtained by Adamson and Sporer for 370 m/ ), 0.17 for 405 m/i, and 0.12 for 435 m. The interesting feature was the calculation that the quantum eflBciencies at 405 and 435 mjuL were too large to be accounted for if they were due to the tail end of the electron transfer absorption band in the near-ultraviolet. It v/as thus shown that... 

Reclamation of cobalt as described is not complete as some formation of Co " by oxidation cannot be avoided, leading to deterioration of the wastewater stream. For the recovery of cobalt from this stream, the usual techniques of precipitation may be applied, leading to carbonate or hydroxide [177], The overall losses are compensated by fresh cobalt, introduced via the carbonyl generator. In order to convert cobalt formate into HCo(CO)4, the presence of palladium on a support as catalyst is recommended [174],... 

Composition of C0CI2 dissociation products in atmospheric-pressure plasma is shown in Fig. 7-80. The initial concentration of C0CI2 is 7.7 mol/kg. Cobalt formation occurs at temperatures exceeding 2500 K. The energy cost of Co production is shown in Fig. 7-81. The minimal energy cost is 13 eV/atom for absolute quenching at a specific energy input of... 

Fig. 26a-c. Motifs found in magnesium-binding proteins a the ring noted in Fig. 24 b an aquated carboxylate motif c stereoview of the motif found in cobalt formate [63]. These motifs are also used by other metal ions that have similar sizes and ligand preferences... 

Cobaltous formate. See Cobalt formate (ous) Cobaltous hydroxide. See Cobalt hydroxide (ous)... 

The individual steps in the cycloaddition are not known but several proposals have been put forward. Our studies build on these proposals. Following the complexation of NBD and the acetylene to the low-valent cobalt, formation of metallacycle IV is likely to occur (Scheme 5). Isolation of 5-10% of side product N (when R = TMS) provides further support for the formation of such a metallacycle, but insertion into the... 

Cobalt.— Formation of the cobaloximes (1) via the reactions in Scheme 6 proceeds... 

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