Metalloorganic addition

Enzymes, like other proteins, have molecular weights ranging from about 12,000 to more than 1 million. Some enzymes require no chemical groups for activity other than their amino acid residues. Others require an additional chemical component called a cofactor—either one or more inorganic ions, such as Fe2+, Mg2+, Mn2+, or Zn2+ (Table 6-1), or a complex organic or metalloorganic molecule called a coenzyme (Table 6-2). Some enzymes require both a coenzyme... 

Kochetkov continued as lecture assistant until 1951, combining this work with research on metalloorganic chemistry in Nesmeyanov s laboratory. He studied organo-mercury compounds, in particular their synthesis by the addition of mercuric chloride to acetylenes. In 1948 Nikolay wrote a thesis and received the Ph.D. degree in chemistry. 

Salts formed with the metalloorganic cations tetraphenylphosphonium and tetra-phenylarsonium can be prepared as relatively large crystals by electrochemical methods and are not air sensitive, contrary to the other monoanionic fullerides mentioned above as a consequence, they have been extensively studied by several methods [40 4]. The composition of the crystals is always two counterions to one fulleride monoanion, and charge neutrality is preserved by one halide ion (Cl , Br or I ) per fulleride ion. The type of the halide ion depends on preparation conditions and can be homogeneous or a mixture of two kinds of halides. This fact introduces an additional disorder into the structure, but as we will see, its impact is relatively weak. 

Most of the catalysts employed in the chemical technologies are heterogeneous. The chemical reaction takes place on surfaces, and the reactants are introduced as gases or liquids. Homogeneous catalysts, which are frequently metalloorganic molecules or clusters of molecules, also find wide and important applications in the chemical technologies [24]. Some of the important homogeneously catalyzed processes are listed in Table 7.44. Carbonylation, which involves the addition of CO and H2 to a C olefin to produce a + 1 acid, aldehyde, or alcohol, uses rhodium and cobalt complexes. Cobalt, copper, and palladium ions are used for the oxidation of ethylene to acetaldehyde and to acetic acid. Cobalt(II) acetate is used mostly for alkane oxidation to acids, especially butane. The air oxidation of cyclohexane to cyclohexanone and cyclohexanol is also carried out mostly with cobalt salts. Further oxidation to adipic acid uses copper(II) and vanadium(V) salts as catalysts. The... 

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