Synthesis of Phenytoin from Benzil by Microwave Irradiation


To synthesis and submit phenytoin from benzil by using a microwave oven and calculate its percentage yield.


The microwave region of Electro-Magnetic spectrum light between IR irradiation and frequency corresponding to the wavelength of 1cm-1
to 1m. The organic compound can be heated by applying energy in the form of microwave high-frequency IR irradiation. The use of this technique can have substantial saving time for laboratory synthesis of drugs and chemicals. Phenytoin is prepared by condensation of benzil and urea under reflux condensation to give the heterocyclic compound Pinnacol. When the pinnacle is treated with sodium hydroxide it’s rearrangement to produce phenytoin as sodium salt and the esterification gives phenytoin as a crude product. This reaction is completed to take place only 2 to 3 minutes of microwave irradiation.



  • Benzil = 1.25g
  • Urea = 0.75g
  • NaOH (30%)= 3.75 ml
  • Methanol = 18.75 ml


1.25gm of benzil, 0.75gm urea, 3.75ml 30% sodium hydroxide and 18.75 ml methanol was taken in a beaker and kept in a Microwave oven for 3 minutes. Then it was cooled to room temperature and 50ml of water was poured, mixed well and filtered. To the filtrate con. HCl was added to get the crude product. Then the product was recrystallized from ethanol.

Melting Point: 295oC to 298oC
Use: Anti-convulsant


Phenytoin was synthesised and reported the following

  1. Theoretical yield =
  2. Practical yield =
  3. Percentage yield =

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