Advanced Techniques of Separation and Purification. The methods of purification of a crude product by fractional crystal-lisation (p. 13) and fractional distillation (p. 25) have the advantages that they can, when required, be applied on a large scale. They have the disadvantages that they cannot be rapidly applied to separate, for example, two components of a crude product whose solubilities in a range of solvents are closely similar or whose boiling-points are very close together. Fractional crystallisation may often be impeded (or prevented) by the formation of mixed crystals, and fractional distillation by the formation of constant boiling-point mixtures, or by less definite co-distillation. Purification by sublimation (p. 23) can also be per-formed on a large scale, but its use is obviously and severely limited to solid compounds having the necessary physical properties. The various types of Chromatographic Separation have been deve-loped partly to avoid the above disadvantages, but (more particularly)
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.