Isopropylidene glycerol hydrogen phthalate as a resolving agent: a study of its diastereomeric salts with (S)- and (R)-1-phenylethylamine

An insight into the mechanism of the highly e cient resolution of 1-phenylethylamine with enantiomerically pure isopropylideneglycerol hydrogen phthalate is provided by comparison of physicochemical and X-ray crystallographic data of the two diastereomeric salts formed by the amine with the S acid. In the nearly identical structures of these salts, the di€erent disposition of the isopropylidene glycerol moiety stands out drawing attention to the critical role played by the chiral part of the acid in the discrimination between the amine enantiomers.