Structure polymorphic configurations

Chemical development Proof of structure and configuration are required as part of the information on chemical development. The methods used at batch release should be validated to guarantee the identity and purity of the substance. It should be established whether a drug produced as a racemate is a true racemate or a conglomerate by investigating physical parameters such as melting point, solubility and crystal properties. The physicochemical properties of the drug substance should be characterized, e.g. crystallinity, polymorphism and rate of dissolution. 

Another approach is to compare polymorphic forms of the same compound. This allows the comparison of molecules with the same constitution and configuration in different crystal fields. Do these different potential environments lead to different conformations There are few comparative crystal structural studies of organic polymorphs. For d-mannitol the molecules had the same conformation in all three polymorphic forms studied with differences in torsion angles for the two that were studied in detail of only a few degrees (see Table I). 

In solution, the several charged species, 2, 3, 4, can occur in equilibrium, depending on the pH of the solution. In the crystalline anhydrous and hydrated amino acids, however, only the zwitterion configuration, 3, is observed. The acidic configuration, 2, occurs in the hydrochlorides and hydrated hydrochlorides, but there are no crystal structures containing the anionic form 4. Polymorphism occurs in the amino acids, but it is relatively rare and certainly no more common than... 

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