These two methods are described below. Method 1 is best used with a moderately polar-nonpolar mixture. Method 2 is used with a moderately polar-very polar mixture. Add the moderately polar solvent such as ethyl acetate a little at a time while maintaining gentle boiling. Continue the addition until the compound just dissolves.
Gravity filter the hot solution.
Wash with a solvent mix of appropriate ratio if necessary. Redissolve the filtrate if necessary. Cool slowly without disturbing, then completely in ice and water. Suction filter the crystals. Wash the crystals with a small amount of chilled solvent mixture.