Dual influence of lithium chloride on the reactivity of polystyryllithium in ethereal solvents

Addition of LiCl to ethereal solutions of polystyryllithium retards propagation of the polymerization at low polymer concentration, but accelerates it at higher polymer concentrations. This phenomenon is accounted for by the dual action of LiCl. Its dissociation yielding free common Li⁺ ions which diminish the concentration of the reactive free polystyryl anions dominates at low electrolyte concentrations. However, at their higher concentrations the Li⁺ scavenging action of LiCl, resulting in the formation of LiClLi⁺ triple ions, becomes important, it reduces the concentration of the free Li⁺ ions and increases, therefore, the proportion of the reactive free polystyryl anions.