The influence of water molecules on the complex formation between K+ and 18-crown-6 and the cryptand (222) in chloroform

The complexation formation between potassium dibenzyldithiocarbamate and 18 -crown-6 and the cryptand (222) was studied in chloroform using calorimetri c titrations. By variation of the molar ratio of the salt and water the inf luence on the reaction enthalpies was studied. With increasing concentratio n of water in chloroform the values of the reaction enthalpies decrease for both ligands. The microsolvation of the cation or ion pair present in solu tion by the water molecules has a pronounced effect on the reaction. Thus t he presence of very small amounts of water cannot be neglected for the extr action of cations from aqueous to chloroform solution. (C) 2001 Elsevier Sc ience B.V. All rights reserved.