Analytical Sciences

Abstract − Analytical Sciences, 17(3), 411 (2001).

Selective Extraction of Palladium(II) with Theophylline Derivatives
Katsuya KAIKAKE and Yoshinari BABA
Department of Applied Chemistry, Faculty of Engineering, Miyazaki University, 1-1 Gakuenkibanadainishi, Miyazaki 889-2192, Japan
Theophylline derivatives with some kinds of alkyl chains were synthesized and used in extraction experiments involving metal ions. Theophylline derivatives have exhibited a high selectivity for palladium over other precious metals and base metals. The extraction of palladium from acidic chloride media has been investigated using theophylline derivatives (= (RN)org) as extractants. Palladium(II) was found to be extracted with 7-octyltheophylline according to the following reaction: PdCl2 + (2RN)org < = > (PdCl2(RN)2)org. The extraction equilibrium constant was determined to be K = 2.67 x 108 (mol dm-3)-2. In addition, the stripping of palladium was performed to an extent of 100% by a single batchwise treatment with a 1.0 mol dm-3 ammonia solution. The stoichiometric relation in the extraction of palladium was supported by an analysis using mass spectrometry.