A reduction in the @[email protected] of certain reactions of a @[email protected] RX in solution [by a path that involves a @[email protected] with formation of R+ (or R ) ions as reaction intermediates] caused by the addition to the reaction mixture of an electrolyte solute containing the 'common ion' X (or X+). For example, the rate of @[email protected] of diphenylmethyl chloride in acetone-water is reduced by the addition of salts of the common ion Cl- which causes a decrease in the @[email protected] concentration of the diphenylmethyl @[email protected] in the scheme:
This phenomenon is a direct consequence of the @[email protected] on @[email protected] equilibria in electrolytic solution. More generally, the common-ion effect is the influence of the 'common ion' on the reactivity due to the shift of the @[email protected] equilibrium. It may also lead to an enhancement of the @[email protected]
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1098 [Terms] [Paper]