Abstract
The conductivities of lithium and quaternary ammonium salts have been measured in propylene carbonate and γ‐butyrolactone at 25°C over the concentration range of 10−2 to 10−3 mol dm−3. The limiting molar conductivities and the ionic association constants were calculated by the expanded Fuoss‐Hsia equation. The mobility of anions in both solvents decreased in the following order: 
. The association constants increased in the following order: 
, 
, while those of the corresponding tetraethylammonium salts were leveled by electrostatic shielding effect of alkyl groups. These results were correlated with ionic radii obtained by MM2 calculation.