Towards a rational design of resolving agents. Part II:Correlation between resolution results and physical properties of diastereomeric salts

Six closely related cyclic phosphoric acids (1a‐f) were compared with respect to their resolving ability towards ephedrine. Variation of the aromatic substituent in the phosphoric acids significantly influences this ability. Studying the results of the resolution experiments as a function of some physico‐chemical properties of the diastereomeric salts reveals a relationship between the resolving ability of a particular phosphoric acid and the difference in heat of fusion of its diastereomeric salts