Azocalixarene. 5: p-Substituted Azocalix 4 arenes as Extractants for Dichromate Anions

In this article, chromium(VI) extraction properties of two azocalix 4 arene based receptors (L4 and L6) are reported. A preliminary evaluation of the binding efficiencies of p-substituted azocalix 4 arene derivatives L4 and L6 was carried out by solvent extraction of Na-dichromate from aqueous solution into dichloromethane at different pH. It was observed that the new compounds are effective extractants for transferring the HCr2O7-/Cr2O72- anions at low pH. The binding ability of these compounds toward HCr2O7-/Cr2O72- anions depends upon Na+ extraction.