SEARCH Articles Figures Tables Cinchona Cinchona alkaloid derived quaternary ammonium salts Cinchona ammonium salts Cinchona salt Cinchona, quaternary ammonium salts bromide Cinchona, quaternary ammonium salts ester, alkylation Cinchona-based quaternary ammonium salts Dimeric quaternary ammonium salts cinchona-derived Quaternary ammonium salts Quaternary salts