Resolution of malic acid by (+)-cinchonine and (–)-cinchonidine

Abstract

(+)-Cinchonine and (–)-cinchonidine have been employed to resolve rac-malic acid. The resulting salts contain the D-malate anion in both cases. The cinchoninium and cinchonidinium L-malates were also crystallised, and the structures of all four salts were analysed in terms of their nonbonding interactions. All four structures display extensive hydrogen bonding, and it is shown that the D-malate salts are more efficiently packed.