A Convenient Approach towards the Synthesis of a "Proton Switchable" Chromium(VI) Extractant Based on Calix[4]arene.

Autor: Ediz, Ozlem, Tabakci, Mustafa, Memon, Shahabuddin, Yilmaz, Mustafa, Max Roundhill, D.
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Zdroj: Supramolecular Chemistry; Apr2004, Vol. 16 Issue 3, p199-204, 6p
Abstrakt: A convenient synthesis and Cr(VI) extraction properties of a new calix[4]arene-based receptor ( 5 ), which has been synthesized from 5,17-diformyl-25,27-dimethoxycarbonylmethoxycalix[4]arene ( 4 ) by treatment with 3-aminomethylpyridine in one step, are described. The receptor 5 contains four pyridinyl groups, two on each rim. Two of them are joined by an amide linkage onto the lower rim, and other two are linked by an imine-type linkage onto the upper rim of the calix[4]arene moiety. Receptor 5 is very soluble in water at low pH (<2.5). Calixarene 5 also represents a good extractant for HCr 2 O 7 - . Thus, the partially protonated form of 5 is an effective extractant for transferring HCr 2 O 7 - ions from an aqueous into a chloroform layer. Deprotonation of 5 results in a reversal, with HCr 2 O 7 - migrating back into the aqueous layer. [ABSTRACT FROM AUTHOR]
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