Estudo da adsorção de especies quirais em crisotila brasileira

AUTOR(ES)
DATA DE PUBLICAÇÃO

1983

RESUMO

Chrysotile is a clay mineral, with unitary cell Mg3Si2O5(OH)4, structured on spiral layers forming tubular fibrils, with positive zeta potential. lt has been observed that several chemical species are efficiently adsorved in chrysotile due to its great surface activity. ln this work, chrysotile was used to support two optically active species: the hemisulphate of (-) ephedrine (1R, 2S) and the (R)-(-)-N(3,5-dinitrobenzoyl-phenylglycine) (DNBPG). Ephedrine is frequently used to intermediate organic syntheses, and DBNPG is one of the most common substances employed in chiral stationary phases of the Pirkle type. The adsorption of ephedrine and DNBPG on chrysotile using several solvents and the ability of enanciomeric separation from chromatografic columns filled with the adsorved chrysotile were studied. From the results, a model for the interaction of weakly acid or basic organic structures with the chrysotile, and for the interaction of the adsorved species with a synthetised enanciomeric mixture, the paranitrophenylethanol, is proposed. The resolution of racemates in liquid chromatography was obtained in preparative scale. ln high performance liquid chromatography, chromatographic peaks were found using hexane/methylene chloride (2:1) as mobile phase. These results allow the proposal of a model for the interaction between ephedrine/DBNPG and chrysotile, which is coherent and consistent with the very nature of the species and with the relevant processes that take place during adsorption.

ASSUNTO(S)

quiralidade adsorção crisotila - brasil

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