| Abstract: | Polymorphic transformations of stearic acid in their crystallization solutions have been studied. When stearic acid crystals were left in the ethanolic saturated mother liquor, the B-form modification was obtained throughout the whole process. In n-hexane and benzene during the first 2–3 hours, the C-polymorph was the predominant form, later transformed progressively into the B-form, so that towards the end of the experiment the whole precipitate was in the B-form. The proposed explanation is that the transformation is due to dissolution caused by thermal fluctuation in the bath, and subsequent precipitation. The dissolution and reprecipitation was followed up by micro photographs. In the presence of Span 60, only C form was obtained in all the solvents. – As a result of this study it is suggested to pay attention to possible solution-mediated polymorphic transformations of the crystallized material which may cause a misleading interpretation of the factors affecting the crystallization of the fatty acid. |
