What properties are desirable when choosing a solvent for re-crystalization?

Question

What properties are desirable when choosing a solvent for re-crystalization?

Answer 1

Mostly solubility.  In graduate school I had a bad habit (?) of using acetone and water.  I would dissolve the compound in acetone at a warm temperature, add H2O until I just saw cloudiness, re-warm to put everything in solution, and then slowly cool.  We used chemwipe boxes filled with cotton to let the solution cool down slowly.

Answer 2

The substance to be re-crystallized must have high solubility in the solvent at high temperatures, and low solubility at low temperatures. Picking a solvent in which the impurities are poorly soluble, is also an advantage.