Crystallization and precipitation: chiral compounds and metals powders

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Crystallization and precipitation are two processes that are widely used in the industry for a vast array of applications. These applications can be classified into two broad groups. The first and most common application is in separating components in solution based on their solubility for recovery or purification. The other is in the production of solid particles via either gas or liquid phase homogenous reactions. The most important consideration in crystallization /precipitation operation is the control of the solid product with respect to its purity, particle size distribution and very often morphology and habit of the produced crystal. For example, in pharmaceutical applications, the crystal morphology and crystal structure can influence the availability of the drug in the receiving organism. The proposed research program consists of two projects both intimately related to crystallization and precipitation. The first project is concerned with the crystallization of enantiomers, a group of compounds which are extremely important in the pharmaceutical and food industries. Enantiomers are pairs of molecules that are mirror images of each other. Since they are similar except for their configuration in space, their physical properties such as solubility, melting and boiling point are identical but their chemical properties can differ. For example, although a large number of drugs are chiral molecules, only one enantiomer is active as a drug. The others may be less active, or even toxic.  The usefulness of being able to isolate the enantiomer of interest is obvious both from economical, medical and environmental points of view. The second project is related to the production of silver powder. High purity silver powders are used as catalysts, transparent coatings, and pigments for glasses and ceramics and they are widely used in the production of microelectronic components. The suitability of the powder for use in such applications depends on the shape, size and size distribution. Thus it is important to predict and control the behavior of the precipitation or crystallization reaction for the attainment of the desired powder properties. The general objective of both projects is to establish the conditions at which the resulting products have the desired properties in terms of their purity size, size distribution and morphology.