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JEE Main levelSingle correct optionDifficulty 2 of 3ro027

In a Birch reduction the alcohol (for example ethanol) added to the Na/ mixture serves as

  1. Athe proton source that protonates the radical anion and the carbanion
  2. Ba catalyst that produces more solvated electrons
  3. Ca hydride donor
  4. Dan oxidising agent that regenerates sodium

Answer: A

The sequence is electron transfer, protonation of the radical anion by ROH, a second electron transfer, and protonation of the carbanion. Ammonia is too weak an acid, so the alcohol provides the protons.
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