When chlorobenzene ($\ce{C6H5Cl}$) reacts with aqueous ($\ce{NaOH}$) solution it first forms sodium phenoxide ($\ce{C6H5ONa}$), and then phenol upon reacting with $\ce{H+}$.

But my question is, why can't $\ce{Na}$ directly replace $\ce{Cl}$ from chlorobenzene by breaking $\ce{Na-O}$ bond instead of breaking $\ce{O-H}$ bond?

  • $\begingroup$ You mean the Na from the NaOH? $\endgroup$ – Simon-Nail-It Mar 5 '16 at 9:15
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    $\begingroup$ Can you clarify what you think the mechanism is for this reaction? I don't quite understand your question. $\endgroup$ – bon Mar 5 '16 at 13:34
  • $\begingroup$ @Simon-Nail-It Yes sir, Na from NaOH $\endgroup$ – TheNewGenGamer Mar 5 '16 at 15:19
  • $\begingroup$ So your question is why can't $Na^{+}$ react directly with chlorobenzene instead of reacting with phenol? $\endgroup$ – Rok Narobe Mar 5 '16 at 15:57
  • $\begingroup$ @RokNarobe No sir, i mean to say that why is the long process used when we can just break the C-Cl bond in benzene and then Na+ can react with Cl to form NaCl and phenyl cation can react with OH- to give phenol. Why is Sodium Phenoxide is being formed before giving phenol ? $\endgroup$ – TheNewGenGamer Mar 11 '16 at 15:04

The mechanism of this reaction is that $\ce{NaOH}$ being a strong base with some extreme conditions abstracts H from C adjacent to C containing Cl while Cl also leaves.

This creates benzyne as an intermediate.

Subsequent addition of $\ce{NaOH}$ forms the phenoxide ion.

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