Ethanoic acid reacts with phosphorus pentachloride to give

  • A. ethanoyl chloride, hydrogen chloride and phosphorus oxychloride
  • B. chloroethane and water
  • C. ethanol and chlorine
  • D. ethanal only

Explanation

The hydroxyl group of the acid is replaced by chlorine, giving the far more reactive acyl chloride, and the misty fumes of hydrogen chloride released make this a useful test for a hydroxyl or carboxyl group. Thionyl chloride achieves the same conversion with gaseous by products that are easier to remove. The acyl chloride is then used to prepare esters and amides.

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