Chemical
Structure
Synonyms:
Acetaminophen ; N-Acetyl-p-aminophenol ; N-(4-Hydroxyphenyl
Theory
Chemicals Required:
1.
para-Aminophenol :
6 g
2.
Acetic anhydride : 6.5 ml
3.
Concentrated
Sulphuric acid : 4 drops.
Procedure:
1.
Weigh 6 g of
para-aminophenol and transfer to a 100 ml thoroughly cleaned and dried conical
flask.
2.
Add to the flask
6.5 ml of acetic anhydride and 3–4 drops of concentrated sulphuric acid
cautiously.
3.
The contents of
the flask may be mixed thoroughly. Warm the mixture on a waterbath previously
maintained at 60°C for about 20–25 minutes with constant stirring.
4.
Allow the contents
of the flask to attain room temperature, and pour it directly into a beaker
having 100 ml of cold water (with a few chips of crushed ice) and stir it
vigorously.
5.
The crude product
obtained in (4) is filtered onto a Büchner funnel using suction,wash
it with plenty of cold water, drain well and dry the product either between the
folds of filter paper and air-dry it or dry it in an electric oven maintained
at 100°C.
The
yield of crude paracetamol (169–170.5°C) is approximately 6.8g.
Recrystallisation:
Dissolve the crude product in 70% (v/v) ethanol and warm it to 60°C ; add 2 g
of powdered animal charcoal (decolourizing carbon). Filter and concentrate the
filtrate over a water-bath. Allow it to cool and large crystals will separate
out.
The
yield of the pure paracetamol (mp 169–170.5°C) is 6.5 g.
Uses
antipyretic and analgesic.
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