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Phenytoin Synthesis

Phenytoin Synthesis
Course

Pharmacy

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Academic year: 2016/2017
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Kerala University of Health Sciences

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Synthesis of Phenytoin

Principle: Base catalyzed reaction between benzyl and urea is used for synthesis of phenytoin. The reaction is proceeding via intramolecular cyclization to form an intermediate heterocylic pinacol, which on acidification yield hydantoin (phenytoin) as a result of 1,2-diphenyl shift in pinacol rearrangement reaction. 1

Aim: To prepare phenytoin from benzil and urea.

Reaction:

Use: It is a common antiepileptic drug.

REQUIREMENTS

Chemicals: Benzil

Urea

Sodium hydroxide

Ethanol

Concentrated hydrochloric acid

Apparatus: Round-bottom flask – 100 ml

Reflux condenser

Crystallizing dish – 500 ml

Heating mantle

Stirrer

Beaker – 400 ml

Filtering flask with Büchner funnel

Graduated cylinders – 100 ml and 50 ml

Petri dish etc.

PROCEDURE

Place 5 g (0 mol) of benzil, 3 g (0 mol) of urea, 15 ml of aqueous sodium hydroxide solution (30%) and 75 ml of ethanol in a round bottomed flask of 100 ml capacity. Set up a reflux condenser with the flask and boil using an electric heating mantle for at least 2 h. Cool to room temperature, pour the reaction mixture into 125 ml of water and mix carefully. Allow the reaction mixture to stand for 15 min and then filter the product under suction to remove an insoluble by-product. Render the filtrate strongly acidic with concentrated hydrochloric acid, cool in ice-water and immediately filter off the precipitated product under suction. Recrystallise at least once from industrial spirit to obtain about 2 g (44%) of pure 5,5-diphenylhydantoin, m. 297-298 °C.

Calculation :

Here limiting reagent is benzil; hence yield should be calculated from its amount taken.

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Phenytoin Synthesis

Course: Pharmacy

999+ Documents
Students shared 2396 documents in this course
Was this document helpful?
Synthesis of Phenytoin
Principle:
Base catalyzed reaction between benzyl and urea is used for synthesis of phenytoin. The reaction
is proceeding via intramolecular cyclization to form an intermediate heterocylic pinacol, which
on acidification yield hydantoin (phenytoin) as a result of 1,2-diphenyl shift in pinacol
rearrangement reaction.1
Aim: To prepare phenytoin from benzil and urea.
Reaction:
Use:
It is a common antiepileptic drug.
REQUIREMENTS
Chemicals: Benzil
Urea
Sodium hydroxide
Ethanol