HYDRATION OF SOME TRIVALENT METAL-IONS EXTRACTED AS PERCHLORATES WITHTRIOCTYLPHOSPHINE OXIDE IN HEXANE

Perchlorates of Sc3+, Y3+, La3+, and Eu3+ have each been extracted fro m 0.1 mol.dem(-3) aqueous solution of mu = 1 with trioctylphosphine ox ide (TOPO) in hexane. The hydration number of the extracted salts has been determined by Karl Fischer titration. Sc3+, Y3+, and Eu3+ are ext racted as the tetra-and hexa-solvates of TOPO but the assumption of oc ta-solvate on addition to the tetra-solvate explains the extraction da ta of La3+ well. The hydration number of tetra-solvates is 2 (Sc3+ and Eu3+), 3 (Y3+) and probably 4 for La3+ ion. That of hexa-and octa-sol vates is 4-5.