CHEM 3112 Lecture Notes - Lecture 2: Miscibility, Crystallization, Hexane
Document Summary
Crystallization= the slow formation of crystalline solid. Precipitation = rapid formation of amorphous solid. Dissolve compound in minimum amount of hot solvent. Remove colored impurities with decolorizing carbon and filtration. Allow solution to cool slowly to room temp. Filter to separate crystal from mother liquor. Alcohols, carboxylic acids and amines may be soluble in water and alcohols. Hexane, ether maybe alcohols used as solvents. Dissolve compound in moderate amount of good solvent. Add poor solvent drop by drop until solution is turbid (cloudy) Add just enough drops of good solvent to remove cloudiness. Scratch inside of flask with glass rod. Obtain crystals from glass rod used for scratching. Reheat oils with more solvent to dissolve then slowly cool while running with glass stirring rod. If oiling out continues, separate oil and try a different solvent (lower boiling but similar ) Heated solvent in bottom of collection flask. Heated stemless funnel and damp filter paper on top of collection flask.
