Re-crystallization

The process of re-crystallization is to take a solid (solute), dissolve it in an appropriate solvent and then isolate crystals from a supersaturated solution. In most cases, a supersaturated solution can be prepared by heating the solvent/solution mixture until all of the solute dissolves. When you then cool the mixture, your solute comes out of solution (supersaturated) and crystals appear. Cooling the mixture and letting it sit for a longer period of time will enhance your recovery.

So, if you have isolate a solid via filtration, you can re-crystallize that solid in the following manner:

• Add the solid to a beaker and then add appropriate solvent.
• Put the beaker containing the mixture on a hot plate and heat to the boiling point of the mixture (add more solvent if the solution is boiling and solid remains).
• When all solid has dissolved, add a couple more mL of solvent.
• Remove the beaker from the hot plate, and let the beaker cool to room temperature (do not place in ice, only let it cool on its own on the bench top).
• After about fifteen minutes, you can place the beaker and contents in an ice bucket to enhance solid recovery.
• Using a vacuum filtration setup, with a Buchner funnel, collect your solid crystals and dry.

This procedure will effectively allow for the formation of crystals and should remove any contaminating chemicals which will likely remain in the Mother Liquor.