Synthesis and crystal structures of lower rim amine and carbamoyl substituted calixarenes as transfer agents for oxyanions between an aqueous and a chloroform phase

The calixarene amides 5,11,17,23-tert-butyl-25,27-(carbamoylmethoxy) calix[4]arene 1, 5,11,17,23-tert-butyl-25,27-(N,N-diethyl-2-carbamoylmethoxy) calix[4]arene 3, 5,11,17,23-tert-butyl-25,27-methoxy-26,28-(N,N-diethyl-2-carbamoylethoxy) calix[4]arene.sodium triiodide 5, 5,11,17,23-tert-butyl-25,27-propoxy-26-(N,N-diethyl-2-carbamoylmethoxy) calix[4]arene 6, 5,11,17,23-tert-butyl-25,26,27,28-(carbamoylmethoxy) calix[4]arene 9, 5,11,17,23-tert-butyl-25,26,27,28-(N,N-diethyl-2-carbamoylmethoxy) calix[4]arene.sodium iodide 11 and 5,11,17,23,29,35-tert-butyl-37,38,39,40,41,42-(carbamoylmethoxy) calix[6]arene 13 have been prepared by reacting the precursor calixarene with either 2-bromoacetamide or 2-chloro-N,N-diethylacetamide. The structures of 5 and 11 have been verified by X-ray crystallography. The crystals of 5, C₅₈H₇₄I₃N₂NaO₆, are monoclinic, P2₁/c, and those of 11, C₇₁H₁₁₂IN₄NaO₁₁, are triclinic P1̄. The calixarene amines 5,11,17,23-tert-butyl-25,27-(2-aminoethoxy) calix[4]arene 2, 5,11,17,23-tert-butyl-25,27-(N,N-diethyl-2-aminoethoxy) calix[4]arene 4, 5,11,17,23-tert-butyl-25,27-propoxy-26-(N,N-diethyl 2-aminoethoxy) calix[4]arene 7, 5,11,17,23-tert-butyl-25,27-methoxy-26-(N,N-diethyl 2-aminoethoxy) cal[4]arene 8, 5,11,17,23-tert-butyl-25,26,27,28-(2-aminoethoxy) calix[4]arene hydrochloride 10, 5,11,17,23-tert-butyl-25,26,27,28-(N,N-diethyl-2-aminoethoxy) calix[4]arene hydrochloride 12 and 5,11,17,23,29,35-tert-butyl-37,38,39,40,41,42-(2-aminoethoxy) calix[6]arene 15 have been synthesized by the borane reduction of either the precursor amide or cyanomethoxy derivative. The structure of 10 has been verified by X-ray crystallography. The crystals of 10, C₅₆H₉₄Cl₂N₄O₁₀, are triclinic, P1̄. The calix[4]arenes 2, 3, 4, 6, 10, 11 and 12 have been investigated as extractants for the anions HPO₄^2-, SeO₄^2-, VO₃^-, ReO₄^-, CrO₄^2-, WO₄^2- and MoO₄^2- from water into a chloroform layer. Measurement of the remaining metal content in the aqueous layer by ICP has been used to obtain the distribution coefficient and percentage extraction into chloroform from solutions having a pH of both 0.85 and 7.0. These data generally show that the calix[4]arene amines are better extractants than the calix[4]arene amides, and that the former are usually better extractants from acidic solutions.