Solvent extraction of divalent palladium and platinum from aqueous solutions of their chloro complexes using an N, N-dimethyldithiocarbamoylethoxy substituted calix[4]arene

Abstract

The compound 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-bromoethoxy)calix[4]arene has been prepared by first converting 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-hydroxyethoxy)calix[4]arene into the tosylate, and then to the product by reaction with LiBr. The compound crystallizes in the trigonal space group P3 221 with a = 13.160(2), c = 25.595(6) A ̊ , a = 90.00(2), β = 90.00(1), γ = 120.000(9) 0, Z = 3, ϱ calc = 1.40 g cm −3 . The final R value for 2391 unique reflections was 0.061. The compound reacts with excess sodium N, N-dimethyldithiocarbamate to give 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2- N, N-dimethyldithiocarbamoylethoxy)calix[4]arene. This compound is an effective extractant for transferring palladium(II) from an aqueous to a chloroform phase. No extraction of PtCl 4 2− is observed under thermal conditions. Under photochemical conditions using a mixture of PtCl 4 2− and PtCl 6 2−, extraction of platinum into the chloroform layer is observed. An explanation for this observation is given.