Cobalt chemical properties

Physical and Chemical Properties. The (F)- and (Z)-isomers of cinnamaldehyde are both known. (F)-Cinnamaldehyde [14371-10-9] is generally produced commercially and its properties are given in Table 2. Cinnamaldehyde undergoes reactions that are typical of an a,P-unsaturated aromatic aldehyde. Slow oxidation to cinnamic acid is observed upon exposure to air. This process can be accelerated in the presence of transition-metal catalysts such as cobalt acetate (28). Under more vigorous conditions with either nitric or chromic acid, cleavage at the double bond occurs to afford benzoic acid. Epoxidation of cinnamaldehyde via a conjugate addition mechanism is observed upon treatment with a salt of /-butyl hydroperoxide (29). 

Nickel is a malleable, ductile, tenacious, slightly magnetic, silvery white metal, which conducts heat and electricity fairly well. It is ferromagnetic at ordinary temperatures but becomes paramagnetic at elevated temperatures. Nickel is closely related in chemical properties to iron and cobalt. While sulphidic sources of nickel account for the world s major nickel supplies, it may be pointed out that lateritic nickel deposits (which essentially constitute an oxidic source of the metal) are more extensive than the sulphidic sources. 

A documentation of the physical and chemical properties of alkylcorrinoids and alkyl-cobalt Bi2 model compounds is presented in a recent review by Hill (41). In this report we shall deal with only those properties of alkylcorrinoids which have proved to be useful when applied to a study of B 12-enzyme mechanisms. 

Lapidus, A., Krylova, A., Kazanskii, V., Borovkov, V., and Zaitsev, A. 1991. Hydrocarbon synthesis from carbon monoxide and hydrogen on impregnated cobalt catalysts. Part I. Physico-chemical properties of 10% cobalt/alumina and 10% cobalt/ silica. Appl. Catal. 73 65-81. 

FT is most compatible with existing distribution for conventional diesel and only minimal adjustments are required to obtain optimal performance from existing diesel engines. Physical properties of FT are very similar to No. 2 diesel fuel, and its chemical properties are superior in that the FT process yields middle distillates that, if correctly processed (as through a cobalt-based catalyst), contain no aromatics or sulfur compounds. 

Jhe distribution of beryllium, boron, titanium, vanadium, chromium, cobalt, nickel, copper, zinc, gallium, germanium, tin, molybdenum, yttrium, and lanthanum in the principal coal-producing beds of the Interior Province has been studied by the U. S. Geological Survey. Data, methods of sampling, and analyses are discussed by Zubovic and others (II, 12). This chapter discusses the occurrence of 13 of these elements with respect to geological and geochemical environments of coal deposition and chemical properties of the elements. Zinc and tin are not included in this study because they were detected in only a few samples. 

Cobalt Compounds. In general the chemical properties arc intermediate between those of iron and nickel. The predominant oxidation stales of cobalt compounds, except for a large class of organumetallie compounds, are 2+ and 3+. Common usage assigns the terms cobaltous and cobaltic. respectively, to these. 

Ionization isomers differ by the exchange of a ligand with an anion or neutral molecule outside the coordination sphere. For instance, [CoBr(NH3)5]S04 and [CoS04(NH3)5]Br are ionization isomers because the Br ion is a ligand of the cobalt in the former but an accompanying anion in the latter. The two compounds have different physical properties the bromo complex is violet and the sulfato complex is red. The chemical properties of the two ionization isomers are also different the red isomer forms an off-white precipitate of AgBr when Agf ions are added, but no precipitate forms after the addition of Ba2-1- ... 

Certain alloys of iron, nickel, and cobalt (Kovar, Fernico, etc.) have thermal expansion curves which nearly match those of borosilicate glasses, and a good bond may be formed between the two. Kovar is similar to carbon steel in its chemical properties. For example, it oxidizes when heated in air and is not wet by mercury. It may be machined, welded, copper brazed, and soft soldered. Silver solders should not be used with Kovar since they may cause embrittlement. At low temperatures Kovar undergoes a phase transformation, and the change in expansion coefficient below this temperature may be sufficient to cause failure of a glass-to-Kovar seal. The transformation temperature usually is below... 

Crystal field theory is one of several chemical bonding models and one that is applicable solely to the transition metal and lanthanide elements. The theory, which utilizes thermodynamic data obtained from absorption bands in the visible and near-infrared regions of the electromagnetic spectrum, has met with widespread applications and successful interpretations of diverse physical and chemical properties of elements of the first transition series. These elements comprise scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper. The position of the first transition series in the periodic table is shown in fig. 1.1. Transition elements constitute almost forty weight per cent, or eighteen atom per cent, of the Earth (Appendix 1) and occur in most minerals in the Crust, Mantle and Core. As a result, there are many aspects of transition metal geochemistry that are amenable to interpretation by crystal field theory. 

Preparation of Cobalt.—The metallurgy of cobalt is complicated by the fact that cobalt ores invariably contain a certain amount of nickel. Since these two metals closely resemble one another in their chemical properties it will be evident that their complete separation on a commercial scale is a matter of considerable difficulty. It is not usually required, however. The details of the actual methods employed in the commercial production of cobalt are kept fairly secret, more particularly as regards the initial stages of the preparation of the crude oxide. We shall, therefore, content ourselves by giving in outline accounts of a few different methods that may be employed. It is convenient to discuss the subject in three sections, namely ... 

Cobalt Di antimonide, CoSb2,3 has also been prepared. It melts with decomposition at 879-5° C. density 7-76 at 0° C. In its chemical properties it resembles the mono-antimonide. 

Compare the chemical properties of radioactive cobalt-60 to those of ordinary cobalt. 

Comparison of cobalt(III) and platinum(II) complexes, therefore, provides further evidence for the duality of mechanism (a and v) for the trans effect in the latter and shows that there is no single order of ligands which can be transferred from one metal cation to another. A comparison of the ligand orders observed for different metal cations should lead to a much better understanding of the importance of different types of bonds between the metal and ligand, and hence of the chemical properties of complexes. It is hoped that this review will stimulate interest in obtaining more experimental data on cis and trans effects in complexes of other metal cations. 

Iron, cobalt, and nickel, with atomic numbers 26, 27, and 28, lie in the center of the first long period, and are described, with their congeners, the platinum metals, as group VIII of the periodic table. They show a. trend in their chemical properties, forming a transition from the metals chromium and manganese, which may assume several oxidation states, and whose higher oxides are acidic, to the more basic and less chemically versatile metals copper and zinc. 

Saito M. A. and Moffett J. W. (2001b) Cobalt speciation in the equatorial Pacific and Peru upwelling region sources and chemical properties of natural cobalt ligands. Am. Soc. Limnol. Oceanogr. Meet. 

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