Synthesis and Comparison of Extraction Properties of p‐tert‐Butylcalix[n]arene Nitrile Derivatives for Selected Metals and Dichromate Anions

The article describes the syntheses and extraction properties of two p‐tert‐butylcalix[6]arene nitrile derivatives (3 and 4). The trinitrile derivative 3 has been synthesized from 5,11,17,23,29,35‐hexa‐tert‐butyl‐37,38,39,40,41,42‐hexahydroxy‐calix[6]arene 1. The compound 1 was directly converted to its hexanitrile derivative (4). In these syntheses, it was considered to explore the role of nitrile sites in the extraction of various metal cations and HCr₂O₇ ⁻/Cr₂O₇ ²⁻ anions. The liquid‐liquid extraction properties of 3 and 4 towards selected alkali/transition metal cations and HCr₂O₇ ⁻/Cr₂O₇ ²⁻ anions are reported. It has been observed that receptor 3 does not extract alkali/transition metal cations effectively, but shows affinity towards HCr₂O₇ ⁻/Cr₂O₇ ²⁻ anions at low pH. The compound 4 is an effective form for transferring Ni²⁺ selectively, while it shows poor transferring ability for HCr₂O₇ ⁻/Cr₂O₇ ²⁻ anions from an aqueous into a dichloromethane layer. It was observed that the cavity size of the calix[n]arenes and the cooperativity of the functionalities play important roles in two phase extraction systems.

Keywords:

• calixarenes
• toxicity
• transition metal ions
• dichromate anion
• selectivity
• liquid‐liquid extraction

5 Acknowledgements

We thank the Research Foundation of The Selcuk University of Turkey for financial support of this work.