Aim:
To synthesize Phenyl Benzoate from Phenol by an acylation reaction
Reference:
F. G. Mann and B. C. Saunders, Practical Organic
Chemistry, 4th Ed, 1974, P. No. 244.
Requirement:
Apparatus:
Beaker, Stirrer, Filtration assembly, etc.
Chemicals:
Phenol,
Benzoyl chloride, 10% sodium hydroxide
Theory/Principle:
Insertion of benzoyl moiety instead of an active hydrogen
atom present in hydroxyl (OH), primary amino (NH) or secondary amino group (NH)
is usually termed as benzoylation reaction. The Process of
benzoylation of compounds containing active hydrogen such as phenol, Aniline,
Alcohol etc. with benzoyl chloride in the presence of aqueous NaOH is called Schotten
Baumann reaction. This particular reaction essentially bears a close resemblance to the phenomenon of acetylation except that in this specific instance
the reagent is (benzoyl chloride) which reacts in the presence of pyridine or 10% NaOH.
The amines are more soluble in acid chloride than in NaOH, the reaction occurs preferably
between benzoyl chloride and amine. In the preparation of benzanilide, NaOH
neutralizes the liberated HCl3 and also catalyze the reaction.
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| Fig. 1 Synthesis of Phenyl Benzoate from Phenol |
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| Fig. 2 Mechanism of Reaction |
Procedure:
- Dissolve 1 g of phenol in 15 ml. of 10% sodium hydroxide solution contained in a strong wide-mouthed bottle of about 50 ml capacity.
- Then add 2 ml. of benzoyl chloride, cork the bottle securely and shake the mixture vigorously for 15 minutes.
- At the end of this time the reaction should be complete, and a solid product obtained, although a faint smell of unchanged benzoyl chloride may possibly still persist, owing to slight occlusion by the solid product, absorption by the cork, etc.
- Filter off the solid ester at the pump, breaking up any lumps on the filter with a spatula, and then wash thoroughly with water and drain.
- Phenyl benzoate is thus obtained as colorless crystals having m.p. 69°.
