Recrystallisation in near-critical solvents

The most common method of recrystallisation and consequent purification of a compound using a liquid solvent relies on the variation and control of solubility with temperature. Usually the starting material is reasonably pure and conditions are chosen so that the impurities do not reach saturation on cooling and only the product required is precipitated. If this does not happen, the recrystallisation is repeated. Another method is the slow addition of an antisolvent a liquid miscible with the solvent, such that the product is less soluble in the greater volume of the mixture. The antisolvent can be chosen so that the impurities are less prone to precipitation. 

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Other uses for near-critical solvents chemical reaction and recrystallisation in near-critical solvents... 

MHM Caralp, AA Clifford, SE Coleby. Other uses for near-critical solvents chemical reaction and recrystallisation in near-critical solvents. In MB King, TR Bott, eds. Extraction of Natural Products Using Near-Critical Solvents. Glassgow, UK Chapman Hall, 1993, pp 50-83. 

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