Purification of substances by a process of freezing and fractional melting under equilibrium conditions

Abstract

\ purifi cation tec hnique has been developed wh ereby a mass of well-defined crystals, form ed by slow cr ystall izat ion of a liquid,. is melted under eq uilibrium co nditi ons into a seri es of fract ions. In this process the entire mass of t he s ubsta nce is fra ctio nated into its g ross impurities and high-purity material. This offers di stinct advantages over co nv en-t ional fra ctional crystallization tec hniques. The apparatus prov ides for co ndu ct in g the fr actionat ing process in a closed iner t system and is well adapted for purifying co mpo unds t hat are co rrosive, toxic, or reactive with air. Details of construction and operation of the apparatus, including experim e ntal resu lts on 2,5-dichlorostyrene, ar c in cluded in t he repo rt .