birch reduction

Question

Birch reduction of benzene yields:

RankGuru · Accepted Answer

1. **Reactants**: Sodium ($Na$) or Lithium metal in liquid Ammonia ($NH_3$) with an alcohol (proton source).
2. **Mechanism**: Electron transfer from the alkali metal to the benzene $\pi$-system followed by protonation.
3. **Result**: Benzene is partially reduced to a non-conjugated diene.
4. **Regiochemistry**: The hydrogens add at the $1$ and $4$ positions to minimize electron-electron repulsion during the intermediate radical-anion phase.
5. **Product**: **1,4-Cyclohexadiene**. 
6. **Note**: This is different from catalytic hydrogenation ($H_2/Ni$), which would give the fully saturated Cyclohexane.

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birch reduction

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