Crystal Growth by Evaporation from a Two Solvent System
Substances that are very soluble in one solvent and insoluble in a second solvent may be good candidates for crystal growth by vapor diffusion, two solvent evaporation or liquid diffusion. The two solvents must be miscible (soluble in each other in all proportions). For evaporation, the good solvent must be much more volatile than the poor solvent.
Suggestions: - Add a small volume (1 mL or more) of the poor solvent to a saturated solution. Add more of the good solvent if any precipitation occurs. Stir to ensure a homogeneous mixture. Cover the solution with foil or wax with a few pin-holes to allow the solution to slowly evaporate. - Some possible "good solvent/poor solvent" pairs are: chloroform/decane, acetone/m-xylene. |