Efficient and Selective Extraction of Fe³⁺ by Mono- and Di-Azocalix[4]arene Derivatives

Abstract

Nine series of chromogenic mono- (A1-A2) and di- (B1-B7) substituted azocalix[4] arene analogues containing more than one azo group were described. Different chelating agents like ester and ketone moieties were grafted on the lower rim position of azocalix[4]arenes. The selective extraction properties of Fe³⁺ cation were studied by liquid-liquid extraction. This extraction process was carried out by using compounds A1-A2 and B1-B7. The results proved that coupling of phenylazo groups onto the upper rim of azocalix[4]arenes yielded greater efficiency and selectivity for carrying the Fe³⁺ cation in the extraction process at pH 2.2.

Keywords:

• Azocalix[4]arenes
• Calix[n]arene
• Fe³⁺ cation
• Metal cations
• Solvent extraction

Notes

(∗) Aqueous phase [metal nitrate = 1.06·10⁻⁴ M]. Organic phase [chloroform (ligand) = 5.3·10⁻⁴ M]. pH: 2.2 (0.01 M NaNO₃/HNO₃, µ = 0.1 with KCl), pH: 3.8; 4.5, and 5.4 M CH₃COONa/CH₃COOH, µ = 0.1 with KCl), at room temperature for 12 h.