Hydroxide Ion Initiated Reactions under Phase Transfer Catalysis Conditions. 9. Dehydrohalogenation of (Haloethyl)benzenes by Quaternary Ammonium Salts

Elimination of HC1 and HBr from (1-and (2-haloethyl)benzenes in the presence of aqueous sodium hydroxide and quaternary ammonium salts which cannot extract hydroxide anion to the organic phase is shown to proceed via a reverse phase transfer process. The catalyst QX promotes the elimination and forms QX•HX adduct which is neutralized at the interphase by the hydroxide base. First-order kinetics is observed under conditions in which the catalyst is stable. Complicated kinetics is obtained when decomposition of the catalyst takes place simultaneously with the reaction.