Alternative pH-Shift Ion-Exchange Chromatography: Quantitative Spectroscopic Monitoring of the Progress of a Reaction.

• Autores: Concepción López Martínez, Mercè Rocamora, Manuel Martínez, Laura Rodríguez
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 85, Nº 3, 2008, págs. 426-428
• Idioma: inglés
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• Resumen

  • The experiment described here for advanced inorganic chemistry undergraduate students includes a solvolysis reaction of [CoCl(NH3)5]2+ in nonaqueous (H3PO4) medium, followed by an alternative way of using ion-exchange chromatography based on the capability of changing the charges of the species by a pH-shift ([Co(H2PO4)(NH3)5]2+/[Co(PO4)(NH3)5]). The complex is then hydrolyzed in acidic medium to produce the corresponding aquocomplex ([Co(H2O)(NH3)5]3+). Time monitoring of the latter process with UV�vis and 31P NMR spectroscopies is conducted and comparison of the two techniques indicate the validity of the results obtained despite the different spectroscopic response to the reaction mixtures.