Aim: To prepare and submit antipyrine from Phenyl hydrazine.
Apparatus:
- RBF
- Beaker
- Measuring Cylinder
- Reflux condenser
- Water bath
- Funnel
- heating mantel
- funnel
Chemicals Required:
- Phenyl hydrazin
- Ethyl acetoacetat
- dimethyl sulphate
- Pet Ether
- Ethanol
- Sodium hydroxide
- Decolourising carbon.
Principle: The basic nitrogen atom attached to the phenylring in the Phenyl hydrazine reacts with ethyl acetoacetate to undergoes cyclization by the removal of ethanol and water molecule. Later the hydrogen attached to the adjacent nitrogen undergoes methylation in presence of dimethy sulphgate to yield Anti-pyrine.
Procedure: Mix together 50g (49ml) of redistilled ethylacetoacetate and 40g(36.5ml) of phenylhydrazine (CAUTION in handling) in a large evaporating dish. Heat the mixture on a boiling water bath in the fume cupboard for about 2 hours and stir from time to time with a glass rod. Allow the heavy reddish syrup to cool somewhat, add about 100 ml of ether and stir the mixture vigorously. The syrup, which is insoluble in ether, will solidify within 15 minutes. Filter the solid at the pump and wash thoroughly with ether to remove coloured impurities. Recrystallize it from hot water or from a mixture of equal volumes of ethanol and water.
Formulation of 2,3-dimethyl-I-phenylpyrazol-5-one by N-methylation.
In a 500-ml three-necked flask, equipped with a dropping funnel, a sealed stirrer until and a double surface condenser and setup in the fume cupboard, place a solution of 10g of sodium hydroxide in 20ml of methanol. Warm the mixture on a water bath and add 36g (27ml)of dimethyl sulphate (CAUTION:toxic) Reflux the mixture for 1hour and allow to cool, with continuous stirring. Distill benzene (fume cupboard) and evaporate the solvent. Recrystallize the crude product from benzene(CAUTION) or benzene-light petroleum, or from hot water with the addition of a little decolourising carbon. The yield of antipyrine (white crystalline solid).
Category: Anti-pyretic.
Calculation:
Molecular Weight of Benzil=210g/mol.
Molecular weight of Phenytoin=252g/mol
210g of Benzil gives 252g of phenothazine
11g of diphenylamine gives =X g of phenothizine =13.2g
%yield = (practical yield/Theoritical yield)X100
Report: Antipyrine was synthesized and the percentage yield was found nto be ____%
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