Cobalt xanthates

A variety of cobalt xanthate structures are available in the literature, including four binary xanthates and a large range of phosphine adducts. By contrast, only one rhodium structure is known and no structure is yet available containing iridium. 

The phosphine adducts of the cobalt xanthates will be described in order of increasing denticity of the phosphine ligand. A five-coordinate trigonal-bipyramidal... 

Tris (O-ethyl dithiocarbonato) cobalt(III) was apparently first prepared by Hlasiwetz15 although some doubt about the composition of his complex exists.6 This and other reported syntheses2,6 involve the reaction of cobalt(II) chloride with the xanthate... 

In recent years, a new class of collectors, consisting of xanthated fatty acids (TY collector), and monoester-modified xanthate (PM230) have found industrial applications with improved metallurgical results. From plant practice, treating oxide copper and copper cobalt ores, two basic flotation methods are practiced (a) sulphidization flotation method, and (b) anionic flotation method. 

In the 1980s, a new collector (i.e. fatty acid-modified xanthate) was introduced into the Kolwezi concentrator with significant improvement in copper recovery. In 1995, collectors from the PM series were tested in the Nchanga concentrate improving results. The plant results obtained in the Kolwezi concentrate using xanthate and TY3 are compared in Table 19.10. Collector TY3 also had a positive effect on cobalt recovery. 

Preparation of an ultrasonic slurry of the sample is occasionally used, as for example in the determination of cobalt, nickel and copper [200], selenium [39] and arsenic and antimony [40]. Extraction of leaves with a chloroform solution of xanthate completely extracted cadmium [41,103]. X-ray fluorescence spectroscopy is a nondestructive method of analysing plant materials if they can be converted into a suitable form for presentation to the instrument. 

Reactions of cobalt carbonyl with nonaromatic thiones differ significantly from the aforementioned conversions. 5-Alkyl xanthates, for example, react by the rupture of C—R and C=S bonds to afford alkoxy alkylidyne tricobalt nonacarbonyl clusters, [RO—CCosfCO),] (41) (vide infra). On the other hand, dithioesters, R C(S)SR, react with [CojfCO) ] to give alkylidyne tricobalt nonacarbonyl clusters in yields between 49 and 74%. The R groups include methyl, isopropyl, and phenyl (42). 

Earlier structural studies of carbohydrates by CD involved introduction of suitable chromophores into the sugar molecule thereby affording derivatives which exibit Cotton effects. These include, among others, xanthates (4-8) or azides (9). Later it was found that some metal ions (10), i.e. copper (11,13), vanadate (14), chromium (15), molybdate (16-22), nickel (23) or cobalt (24,25) ions form complexes with carbohydrates, which show appreciable Cotton effects. 

Substantial effort has been directed toward the control of vinyl acetate (VAc) radical polymerization using living radical polymerization (LRP) methods, including atom transfer radical polymerization, degenerative transfer through alkyl iodide,dialkyl tellurium, trithiocarbonate, xanthate, and cobalt acetylacetonate The focus of... 

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