Solvent Extraction of Europium(iii) With Crown Ethers and Picrate Ions

The extraction of europium(III) with 15-crown-5 (15C5), benzol-crown-6 (B15C5), 18-crown-6 (18C6) or dibenzo-18-crown-6(DB18C6) and picrate anion into chloroform was measured at 25°C. It was found that the stoichlometry in the species extracted is 1:2:3 with respect to europium(III), each crown ether employed and picrate ion. The extraction constants defined as Kex=([EUE2A3])o/[Eu3+]a)x[E]a-2[A-a-3 were measured to be 108.2, 1011.1, 1013.3, and 1013.3 for 15C5, B15C5, 18C6, and DB18C6, successively.