ORGANIC cHEMISTRY - Iv

Experiment 6

Aim of the Experiment:

Purification of Organic Compound by Sublimation Method.

Principle:

1. Sublimation: It involves the direct conversion of a solid into the gaseous state on heating without passing through the intervening liquid state and vice versa on cooling.

2. Purification: The process by which contaminant parts can be removed I order to get pure substances is termed as purification.

3. A large number of methods are available for the purification of substances. The choice of the method, depends upon the nature of the substance and the type of impurities present in it. Important methods commonly employed for the purification of organic substances are:

(i)Filtration (ii)Crystallization or Recrystallization (iii)Fractional Crystallization (iv)Sublimation (v)Simple distillation (vi)Fractional Distillation (vii)Distillation under reduced pressure (viii)Steam Distillation (ix)Differential Extraction (x)Chromatogrpahy

4. Once the substance is purified by any of the above mentioned methods.

5. Sublimation is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point in its phase diagram.

6. The reverse process of sublimation is deposition

7. Compounds that sublimes are:

(a)Inorganic Compounds: CO₂, I₂, As etc.

(b)Organic Compounds: Camphor, Naphthalene, Benzoic Acid, Benzophenon etc.

Materials required:

(I)Apparatus: Evaporating dish, Glass funnel, Filter paper, Sand bath, Cotton, Tripod

Burner etc.

(II)Chemical: Impure organic compound.

Procedure:

Take 10 gram given impure organic compound in evaporating dish. Now make a hole in the middle of the filler paper and keep it on evaporating dish and then put the funnel on it as shown in the figure. Close the narrow end of the funnel with cotton plug. Heat it on sand bath with slow flame of the burner. After few minutes crystal forms on the inner part of the funnel and is pure form of the compound.

Take m.p. of the purified crystal and verify purity of compound by comparing it with

the m.p. of "the pure compound.

Result & Conclusion

(1 ) Given compound is _____________________and its m.p. is_____ °c.

(2) M.P. of the purified organic compound is ________ °c.

Reference Material:

Sublimation

Questions:

Note down other methods of purification.