CONDUCTANCE STUDY OF ALKALI-METAL COMPLEXES WITH 4'-CARBOXY-BENZO-24-CROWN-8 AND 4'-AMIDO-BENZO-24-CROWN-8 IN NITROMETHANE, ACETONITRILE AND DIMETHYLFORMAMIDE SOLUTIONS

Synthetic procedures have been developed for the preparation of two ne w crown ethers 4'-carboxy-benzo-24-crown-8 (COOH-B24C8) and 4'-amido-b enzo-24-crown-8 (CONH2-B24C8). The formation of alkali metal complexes with the two crown ethers was investigated in nitromethane, acetonitr ile and dimethylformamide solutions conductometrically at 25.0 degrees C. Stability constants of the resulting 1:1 complexes were determined by the molar conductance-mole ratio data. In all cases, CONH2-B24C8 w as found to form a more stable alkali complex than does COOH-B24C8. Fo r both crown ethers, and in all three solvents used, the stability of the resulting alkali complexes was found to vary in the sequence K+ > Rb+ > Cs+ > Na+ > Li+. The stabilities of the complexes varied inverse ly with the Gutmann donicity of the solvents.