Cobalt carbonate, pure

Given the reaction and the very high stability constants involved, the production of cobalt carbonic anhydrase would require a solution not of ACS-grade cobalt nitrate but a 99.999999999999. .. 999% pure cobalt nitrate solution. What happened in the lab synthesis was that trace metals in the ACS-grade salt were selectively bound to the apo-carbonic anhydrase because their stability constant advantage was orders of magnitude over that of cobalt. The sample used to discover this was sub-milligram in mass. 

Fifty grams of pure cobalt carbonate are prepared by slowly adding a saturated solution of the equivalent quantity of the chloride, nitrate, or sulfate to a hot solution of 60g of anhydrous sodium carbonate in 600ml of water. Some effervescence takes place The mixture is digested at the boiling point with continual stirring for at least 16 minutes and then suction-filtered, washed freely with hot water, and pressed as dry as possible mi the filter. Alternatively, 51g of technical cobalt carbonate may be dissolved in the minimum amount of 63f hydrochloric add (about 140ml), filtered, and reprecipitated as described ... 

Cobaltous carbonate, C0CO1. is found almost pure in the mineral sphaerocobaltile in the Republic of Zaire and less extensively in Zambia. The pale-red anhydrous salt is obtained by reaction in solution of an alkaline carbonate and a cobaltous salt under a slight pressure of carbon dioxide (up 10 I atmosphere) and subsequent heating at 140 C The commercial salt is violet-red in color, partially hydrolyzed with an indeterminate composition. It is insoluble in H 0 and alcohol, bul dissolves easily in inorganic and organic acids, and is often used for the preparation of other salts. According to the thermal conditions it decomposes to the different types of oxides. 

Physical Properties.—Cobalt is a silver-white metal which, when pure, may be machined in a lathe as readily as pure nickel or pure iron. The commercial metal, containing small percentages of carbon, machines after the manner of mild steel. When under corresponding conditions cobalt is harder than nickel and iron.9 The effect of carbon between 0-06 and 0-37 per cent, is not sufficient to counteract that of slight variations in the heat treatment. The tensile strength of cobalt when pure, cast, and unannealed is 34,400 lb. per square inch, which value is increased to 59,700 lb. with a carbon content of 0 062 per cent. and to 61,900 lb. when the carbon reaches 0-25 per cent. 

Potassium Cobalti-nitrite, K3Co(N02)6. H20, is the most familiar example of this type. It is also known as cobalt yellow and Fischer s salt in honour of its discoverer.1. It is readily prepared by adding potassium nitrite to an aqueous solution of a soluble cobalt salt acidified with acetic acid. It results in a very pure condition when cobalt carbonate is suspended in an aqueous solution containing an equivalent amount of potassium carbonate or nitrite, and treated with nitrous fumes (resulting from the action of nitric acid upon arsenious oxide) until it has suffered complete decomposition.2 The amount of combined water varies from 0 to 4 molecules according to circumstances. 

Ca.rbonylProcess. Cmde nickel also can be refined to very pure nickel by the carbonyl process. The cmde nickel and carbon monoxide (qv) react at ca 100°C to form nickel carbonyl [13463-39-3] Ni(CO)4, which upon further heating to ca 200—300°C, decomposes to nickel metal and carbon monoxide. The process is highly selective because, under the operating conditions of temperature and atmospheric pressure, carbonyls of other elements that are present, eg, iron and cobalt, are not readily formed. 

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. 

Delpeux S., Szostak K., Frackowiak E., Bonnamy S., Beguin F. High yield of pure multiwalled carbon nanotubes from the catalytic decomposition of acetylene on in-situ formed cobalt nanoparticles. J. Nanosc. Nanotech. 2002 2 481-4. 

The formation of bulk cobalt carbide is quite a slow process since it requires the diffusion of carbon into the cobalt bulk. It was reported that the full conversion of unsupported and reduced Co to Co2C only occurred after 500 h of exposure to pure CO at 230°C. Increasing the reaction temperature resulted in a faster rate of carburization.81 Bulk cobalt carbides are considered to be thermodynamically metastable species, and therefore Co2C will decompose to hep cobalt and graphite, while Co3C will decompose to fee cobalt and methane. Thermal decomposition of bulk carbides under an inert atmosphere is believed to occur at 400°C.81 Hydrogenation of the bulk carbides is believed to be a fast process and occurs around 200°C.82 83... 

In the case of cobalt (R = /-Pr)61 the anion has a low stability and decomposes in a few hours, probably by demolition with carbon monoxide. With rhodium185) and iridium102) (R = OMe-), it has been possible to isolate the carbomethoxy anion in a pure form. The carboalkoxy group undergoes further reaction with sodium hydroxide to give the corresponding dianion18 s) ... 

The amidocarbonylation of aldehydes provides highly efficient access to N-acyl a-amino acid derivatives by the reaction of the ubiquitous and cheap starting materials aldehyde, amide, and carbon monoxide under transition metal-catalysis [1,2]. Wakamatsu serendipitously discovered this reaction when observing the formation of amino acid derivatives as by-products in the cobalt-catalyzed oxo reaction of acrylonitrile [3-5]. The reaction was further elaborated to an efficient cobalt- or palladium-catalyzed one-step synthesis of racemic N-acyl a-amino acids [6-8] (Scheme 1). Besides the range of direct applications, such as pharmaceuticals and detergents, racemic N-acetyl a-amino acids are important intermediates in the synthesis of enantiomeri-cally pure a-amino acids via enzymatic hydrolysis [9]. 

Intermolecular addition of radicals, generated by photo-electrochemical catalysis, to activated alkenes can also be brought about. The reaction of 66 is used as a key step in one synthesis of the insect pheromone, brevicomin [219]. The reaction of a secondary radical from 67 occurs at low cathode potentials and without photochemical assistance [219]. This illustrates the equiibrium between a secondary al-kylcobalt(m) species and the radical - cobalt(ii) pair. The carbon radical is eventually captured by reaction with the alkene. Further steps in the synthesis lead to four isomers of the pheromone, multistriatin, each of which is a pure enantiomer since... 

Cobalamin catalysed electrochemical reduction of the 2-chloroethanol ester 68 at negative potentials, without photochemical assistance, leads to a 1,2-elimination process (see p. 115) [228]. This contrasts with the lack of 1,2-elimination during reaction of 66 and 67, Thus in the purely electrochemical carbon-cobalt bond... 

Cobalt octacarbonyl is used as a catalyst in the Oxo process (see Carbon Monoxide). It also is used as a catalyst for hydrogenation, isomerization, hydrosilation and polymerization reactions. The compound is also a source of producing pure cobalt metal and its purified salts. 

The patent literature on the synthesis of bismaleimides is quite extensive. It has always been the target to optimize the synthetic conditions in order to maximize the yield of pure bismaleimide by minimizing the side reactions. Low cyclization temperatures were found to be advantageous and could be achieved with catalysts such as triethyl amine (20), cobalt acetate (21) and sodium carbonate (22) or metal salts in combination with tertiary amines (23). 

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