Cobalt compounds also

The copper compounds are blue. The carbon is black. Cobalt compounds also are shades of blue. 

CoAsS, are also used as sources. The ore is roasted and Co is precipitated as the hydroxide and then reduced to Co with carbon (hep below 417 - C, cep to m.p.). The metal is silvery white and readily polished. It dissolves in dilute acids and is slowly oxidized in air. Adsorbs hydrogen strongly. The main use of cobalt is in alloys. Cobalt compounds are used in paints and varnishes, catalysts. Cobalt is an essential element in the diet. World production 1976 32 000 tonnes metal. 

MetaUic cobalt dissolves readily in dilute H2SO4, HCl, or HNO to form cobaltous salts (see also Cobalt compounds). Like iron, cobalt is passivated by strong oxidizing agents, such as dichromates and HNO, and cobalt is slowly attacked by NH OH and NaOH. 

Cobalt(II) hydroxide [1307-86-4], Co(OH)2, is a pink, rhombic crystalline material containing about 61% cobalt. It is insoluble in water, but dissolves in acids and ammonium salt solutions. The material is prepared by mixing a cobalt salt solution and a sodium hydroxide solution. Because of the tendency of the cobalt(II) to oxidize, antioxidants (qv) are generally added. Dehydration occurs above 150°C. The hydroxide is a common starting material for the preparation of cobalt compounds. It is also used in paints and Hthographic printing inks and as a catalyst (see Paint). 

Cobalt compounds can be classified as relatively nontoxic (33). There have been few health problems associated with workplace exposure to cobalt. The primary workplace problems from cobalt exposure are fibrosis, also known as hard metal disease (34,35), asthma, and dermatitis (36). Finely powdered cobalt can cause siUcosis. There is Htfle evidence to suggest that cobalt is a carcinogen in animals and no epidemiological evidence of carcinogenesis in humans. The LD q (rat) for cobalt powder is 1500 mg/kg. The oral LD q (rat) for cobalt(II) acetate, chloride, nitrate, oxide, and sulfate are 194, 133, 198, 1700, 5000, and 279 mg/kg, respectively the intraperitoneal LD q (rat) for cobalt(III) oxide is 5000 mg/kg (37). 

For cobalt phthalocyanines (PcCo, PcCoX), besides the most common method starting with phthalonitrile and cobalt(II) chloride in ethylene glycol, 130-277 279 some other methods have been employed. Other cobalt compounds used are cobalt(II) acetate127 or acetylacetonate.279 Besides using solvents like 2-ethoxyethanol279 and 2-(dimethylamino)ethanol,121 the reaction has also been performed without solvent.137,262 The central metal may exhibit the oxidation states +11 (PcCo) and + III (PcCoX).279... 

Reaction of K3Co(CN) with PMMA. A 1.0 g sample of PMMA and 1.0g of the cobalt compound were combined in a standard vessel and pyrolyzed for 2 hrs at 375°C. The tube was removed from the oven and the contents of the tube were observed to be solid (PMMA is liquid at this temperature). The tube was reattached to the vacuum line via the break-seal and opened. Gases were determined by pressure-volume-temperature measurements on the vacuum line and identified by infrared spectroscopy. Recovered were 0.22g of methyl methacrylate and 0.11 g of CO and C02. The tube was then removed from the vacuum line and acetone was added. Filtration gave two fractions, 1.27g of acetone insoluble material and 0.30g of acetone soluble (some soluble material is always lost in the recovery process). The acetone insoluble fraction was then slurried with water, 0.11 g of material was insoluble in water. Infrared analysis of this insoluble material show both C-H and C-0 vibrations and are classified as char based upon infrared spectroscopy. Reactions were also performed at lower temperature, even at 260°C some char is evident in the insoluble fraction. 

Cyanide s binding to metallic ions is also employed in a reaction with cobalt-containing compounds that yields cyanocobalamin (see Section 2.6). Cobalt compounds generally are not used because of their toxicity however, Co2EDTA (Klimmek et al. 1983) and hydroxocobalamin (Benabid et al. 1987 Mengel et al. 1989 Mushett et al. 1952) have been used as antidotes both in clinical and laboratory trials. Cardiac toxicity from Co2EDTA use under clinical conditions has raised caution in its clinical use, as the cardiac... 

The spectrum of sodium cobaltinitrite shown in Fig. 13 is also of type I with the maximum at 27 ev. The spectrum differs from the ammonia and ethylene diamine coordinated cobaltic compounds in yielding a pattern... 

The solution on concentration and cooling forms crystals of hexahydrate which on heating with SOCI2 dehydrates to anhydrous cobalt(II) chloride. Alternatively, the hexahydrate may be converted to anhydrous C0CI2 by dehydration in a stream of hydrogen chloride and dried in vacuum at 100-150°C. The anhydrous compound also may be obtained by passing chlorine over cobalt powder. 

Cobalt hydrocarbonyl is a very reactive compound. It reacts extremely rapidly with triphenylphosphine, probably by a first-order dissociation mechanism, producing cobalt hydrotricarbonyl triphenylphosphine (44). This demonstrates the very ready replacement of one ligand by another. Cobalt hydrocarbonyl also catalyzes the isomerization of olefins. Under conditions of the hydroformylation reaction, olefin isomerization is observed. But there is controversy as to whether or not rearranged aldehydes (aldehydes which cannot be produced by simple addition to the starting olefin) are produced mainly by rearrangement of an intermediate in the reaction (28, 75, 55) or by reaction of isomerized olefins (55). 

Cobalt hydrocarbonyl reacts rapidly with conjugated dienes, initially forming 2-butenylcobalt tetracarbonyl derivatives. These compounds lose carbon monoxide at 0°C. or above, forming derivatives of the relatively stable l-methyl-ir-allyl-cobalt tricarbonyl. As with normal alkylcobalt tetracarbonyls, the 2-butenyl derivatives will absorb carbon monoxide, forming the acyl compounds but these acyl compounds also slowly lose carbon monoxide at 0°C. or above, forming 7r-allyl complexes. The acyl compounds can be isolated as the monotriphenylphosphine derivatives (47). 

Cobalt[III] acetate (see Cobalt and eobalt compounds) Cobalt-aluminium-chromium spinel (see Cobalt and cobalt compounds) Cobalt and cobalt compounds (see also Implants, surgical)... 

Agriculture therefore depends on there being a sufficient supply of inorganic nutrients to plants. Cereals, vegetables, fruit-bearing trees or plants, and animal fodder require bioavailable nutrients, that is, nutrients in forms that they can use. Since intensive agriculture depletes many natural nutrients, synthetic nutrients (fertilizers) must be supplied.1-7 In particular, we need to fix the inert N2 of the atmosphere as soluble, reactive compounds such as nitrates, ammonia, and ammonium salts. Other major fertilizer components are sulfate, potassium, and phosphate ions. It may also be necessary to provide trace nutrients, such as cobalt compounds, or to remove excess soil acidity by treatment with lime (CaO). World fertilizer demand in the year 2001 is expected to be about 1.5 x 10s metric tons N, 7.6 x 107 metric tons P2O5, and 6.7 x 107 metric tons K2O these projections represent an... 

Several mixed-metal clusters containing platinum and cobalt are known and some of them have been employed as methanol homologation catalysts.1 Among them, the title compound2 was first prepared unambiguously from the reaction of dichloro[l,2-ethanediylbis(diphenylphosphine)]platinum with sodium tetracarbonylcobaltate, Na[CO(CO)4]. The compound also may be prepared by the reaction of [l,2-ethanediylbis(diphenyl-phosphine)]bis(phenylethynyl)pIatinum with Co COJg.1... 

Reduced synthesis. The synthesis of enzymes may be decreased, resulting in a decrease in the in vivo activity. With cytochrome P-450 there are a number of ways in which this occurs. Thus, administration of the metal cobalt to animals will decrease levels of cytochromes P-450 by inhibiting both the synthesis and increasing the degradation of the enzyme. Thus, cobalt inhibits S-aminolaevulinic acid synthetase, the enzyme involved in heme synthesis. Cobalt will also increase the activity of heme oxygenase, which breaks down the heme portion to biliverdin. The compound 3-amino, 1, 2, 3-triazole decreases cytochromes P-450 levels by inhibiting porphyrin synthesis. 

Cobalt compounds, - particularly salts of organic acids, such as cobalt(II) octanoate369-371 with aluminum alkyls, are also suitable catalysts in hydrocarbon solvents. An A1 Co ratio higher than 1 and water370-372 are essential to obtain high catalytic activity and high cis selectivity.184,363 Polybutadiene with a high cis content can also be synthesized by nickel-based catalysts. Of the... 

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