Studies on the Extractive Behaviour of 12-Heteropoly Acids. Part II : Extraction of 12-Molybdophosphoric, 12-Tungstosilicic and 12-Molybdosilicic Acids

The extractive behaviour of 12-molybdophosphoric (H3PMo12O40), 12-molybdosilicic (H4SiMo12O40) and 12-tungstosilicic (H4SiW12O40) acids into various organic solvents have been studied. The order of extraction of H3PMo12O40 into oxygenated organic solvents is very similar to that of H3PW12O40. The oxygenated organic solvents extract H3PMo12O40 and H3PW12O40 better than H4SiM12O40 and H4SiW12O40. Equilibria involved in the extraction process are discussed and the extraction constants have been calculated. Extraction data give support to the view that 12-heteropoly acids are extracted into oxygenated organic solvents in the form of solvated ion pairs. From 0·5. M LiCl solution, salts of the type LiH2M12O40 and LiH3M12O40 are extracted into the organic phase (where M = Mo or W)