Crystallization of a salt of a weak organic acid and base: Solubility relations, supersaturation control and polymorphic behavior

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Abstract

Control of crystallization processes for organic salts is of importance to the pharmaceutical industry as many active pharmaceutical materials are marketed as salts. In this study, a method for estimating the solubility product of a salt of a weak acid and weak base from measured pH-solubility data is described for the first time. This allows calculation of the supersaturation of solutions at known pH. Ethylenediammonium 3,5-dinitrobenzoate is a polymorphic organic salt. A detailed study of the effects of pH, supersaturation, and temperature of crystallization on the physical properties of this salt shows that the desired polymorph may be produced by appropriate selection of the pH and supersaturation of crystallization. Crystal morphology is also controlled by these crystallization conditions. © 2005 American Chemical Society.

Bibliographical metadata

Original languageEnglish
Pages (from-to)5273-5278
Number of pages5
JournalJournal of Physical Chemistry B
Volume109
Issue number11
DOIs
Publication statusPublished - 24 Mar 2005

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