Manganese solvent-exchange

Manganese. The solvation structures and kinetics of solvent exchange reactions of Mn in six nitriles have been studied by NMR spectroscopy and the activation energies determined. 

Solvent exchange rates have been measured, by n.m.r. spectroscopy, for two further high-spin iron(m) porphyrins and a manganese(m) porphyrin... 

The catalytic application of clays is related closely to their swelling properties. Appropriate swelling enables the reactant to enter the interlamellar region. The ion exchange is usually performed in aquatic media because the swelling of clays in organic solvents, and thus the expansion of the interlayer space, is limited and it makes it difficult for a bulky metal complex to penetrate between the layers. Nonaqueous intercalation of montmorillonite with a water-sensitive multinuclear manganese complex was achieved, however, with the use of nitromethane as solvent.139 The complex cation is intercalated parallel to the sheets. 

L-Arabinose isomerase has been purified from Escherichia coli. The enzyme catalyzes the isomerization of L-arabinose to L-ribulose by a proton transfer mechanism in contrast to xylose isomerase which uses a hydride transfer mechanism to perform a similar isomerization [20], This enzyme has high substrate specificity for L-arabinose, and its catalytic activity is dependent on manganese(II). It has been shown, however, that the enzyme could catalyze the exchange of the proton attached to C2 of arabinose with the solvent even in the absence of metal ion [20],... 

Determination of manganese in urine can be made by flame AAS after extraction into an organic solvent (Van Ormer and Purdy 1973) and after ion-exchange separation (Pan-tucek, 1981). Solvent extraction procedures have also been described for GF-AAS (Buchet et al.. 1976 Watanabe et al., 1978). As the direct determination of manganese in... 

Chemical treatment of a sample also may be used to control interferences. A number of techniques are available, including separation by precipitation, solvent-solvent extraction, and ion exchange techniques. For example, 8-hydroxyquinoline can be used to precipitate and separate a number of elements, such as manganese, copper, cobalt, nickel, and iron, from other major matrix elements. The test solution therefore has fewer extraneous elements present and fewer possibilities of interference exist. 

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