recrystallisation of impure organic compound

1. PRACTICAL ORGANIC
CHEMISTRY
Prepared By
Ms.Sayyed Mohsina

2. OBJECT
• To perform the recrystallization of a given impure organic
compound.

3. REQUIREMENTS
• Apparatus required
• Beaker ,conical flask, water bath ,reagent bottle, measuring
cylinder, pipette, glass rod, spachula , funnel etc
• Chemicals required
• Solvent and sample of organic compound

4. THEORY
• Crystallization is a process to purify solids.Crystallization may
be defined as the process in which a solid compound
precipitates from a saturated solution in the form of crystals.
Saturation is usually effected through cooling .
• Purification by recrystallization depends on the following facts:
1. Different solids have different solubilities in a given solvent.
2. Most solids are more soluble in hot than in cold solvents.

5. RECRYSTALLIZATION
• In recrystallization procedure,an impure or crude solid dissolve
in Hot solvent.
• As a hot saturated solution cools, the solute precipitated out.
• The pure product crystallizes out and the impurities remains in
the solvent or stay dissolved in it.

6. PROCEDURE
• Weigh about one gram of unknown impure organic compound.
• Dissolved the weighed sample in the small amount of selected solvent .
• The suitable solvent obtained by making a solubility test on pure unknown
compound so as to choose the suitable solvent.
• Heat the solution in water bath to completely dissolve the sample.
• When all the the solid is in the solution, remove from the water bath.
• Place the Beaker in an ice bath For crystallization process.
• Now filter the solution to isolate the crystals.
• Carefully remove the crystals from filter paper to watch glass and allow it
to dry.

7. RESULT
• Recrystallization of given impure organic compound was
performed.