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Selectinn a Solvent for Recrystallization Typical dirertions in laboratorj mnnualx fur doing soluhdity teuw suggest adding a specific volume of solvent to a specific amount of compound. This procedure often rrsulto in .selecting a solvent I'm which the compaund:solvent ratio is exceasivrly high ur too low. Hy using rhe following slightly modified procedure, one can determine the optimum a m o m t of solvrnc to use instead of just using some arhrtrary amount. I'lace a few crystals of the compound in a small test ruhe. Add one or twodropa of solvent and shake. If the crysrala do nor dissolve.eenrlv warm the rube. whilpxhakinr it to nromotesrnwth boiling. If thecrystalsdiesolve.stop hearing;allow the solution'& co& and watch for reerystalliza&n. f t h e crystals do not dissolve a n warming, then add one or two more drops of solvent and continue warming. Repeat the addition of solvent followed hy heating until the crystals dissolve or until i t is very dear that they will not. When they dodissolve, allow the solution to cool and watch for recrystallization. (Additional solvent may he needed to account for loss through evaporation.)
Gene A. Hlegel
California State Unaersity, Fullerton Fullerton. CA 92634
Volume 63
Number 3
March 1986
273
