Polymer resin selenium

Suzuki, T. M., Tanaka, D. A. P., Tanco, M. A. L., Kanesato, M., H., Yokoyama, T., Adsorption and removal of oxo-anions of arsenic and selenium on zirconium(IV) loaded polymer resin functionalized with diethylenetriamine-N, N,N ,N -polyacetic acid, J. Environ. Monit., 2, 2000, 550-555. 

Another example of the resin-capture-release technique which should see widespread applications in the future is the selenium-mediated functionalization of organic compounds. Polymer-supported selenium-derived reagents [34] are very versatile because a rich chemistry around the carbon-selenium bond has been established in solution and the difficulties arising from the odor and the toxicity of low-molecular weight selenium compounds can be avoided. Thus, reagent 26 (X = Cl) was first prepared by Michels, Kato and Heitz [35] and was employed in reactions with carbonyl compounds. This treatment yielded polymer-bound a-seleno intermediates, which were set free back into solution as enones from hydrogen peroxide induced elimination. Recently, new selenium-based functionalized polymers 26 (X = Br)-28 were developed, which have been utilized in syntheses according to Scheme 11 (refer also to Scheme 3) [36],... 

Scheme 18.31 Synthesis of a library of benzopyrans employing the use of a polymer-supported selenium resin.

Amorphous phase, of polymers, 20 400 Amorphous polymers, 10 203 crystallization of, 19 844 Amorphous red selenium, 22 74 Amorphous regions, in fibers, 11 171 Amorphous resins, use in thermoforming, 19 555... 

Specimen preparation is simple, involving compressing a disc of the polymer sample for insertion in the instrument, measurement time is usually less than for other methods, and X-rays interact with elements as such, i.e., intensity measurement of a constituent element is independent of its state of chemical combination. The technique has some drawbacks, and these are evident in the measurement of cadmium and selenium. For example, absorption effects of other elements present, e.g., the carbon and hydrogen of a PE matrix, and excitation of one element by X-rays from another, e.g., cadmium and selenium affect one another. The technique has been applied to the determination of metals in polybutadiene, polyisoprene, and polyester resins [1]. The metals determined were cobalt, copper, iron, nickel and zinc. The samples were ashed, and the ash dissolved in nitric acid before X-ray analysis. Concentrations as low as 10 ppm can be determined without inter-element interference. 

Selenium-based linkers 590 can also be synthesized from polystyrene via lithiation and subsequent addition of dimethyldiselenide to the polymer support. Reaction of bromine gives selenenyl bromide that can be reduced to the lithium selenium resin in the presence of liBH4 that is alkylated subsequently [318]. Other approaches include the addition of former synthesized selenium-containing building blocks to the resin, for example, the hnker systems generated by Elofsson et al. [319] and Nakamura et al. [320,321]. 

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