Synthesis of Phenylacetic Acid from Benzyl Chloride

[Ranof]

Overall Reaction:​

C₆H₅CH₂Cl → C₆H₅CH₂CN → C₆H₅CH₂COOH

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Materials and Reagents:​

• Benzyl chloride (C₆H₅CH₂Cl)
• Sodium cyanide (NaCN)
• Ethanol
• Water
• Concentrated hydrochloric acid (HCl) or sulfuric acid (H₂SO₄)

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Procedure:​

1. Cyanation Reaction:
   • In a round-bottom flask equipped with a reflux condenser and a magnetic stirrer, dissolve sodium cyanide in a mixture of water and ethanol.
   • Add benzyl chloride slowly to the mixture while stirring.
   • Heat the reaction mixture to 60–70°C and reflux for 4–6 hours.
   • This step results in the formation of phenylacetonitrile (C₆H₅CH₂CN).
2. Acidic Hydrolysis:
   • Transfer the reaction mixture to another flask and add concentrated hydrochloric acid or sulfuric acid.
   • Reflux the acidic mixture at around 100°C for 4–8 hours to hydrolyze the nitrile group into a carboxylic acid group.
   • The product of this step is phenylacetic acid (C₆H₅CH₂COOH).
3. Work-up and Purification:
   • Cool the reaction mixture to room temperature.
   • Extract the organic product using diethyl ether.
   • Wash the organic layer with water and dry over anhydrous sodium sulfate.
   • Remove the solvent under reduced pressure and purify the crude product by recrystallization from water or ethanol.