My textbook has the following reaction given as a special case of Intramolecular Cannizzaro reaction: enter image description here

As far as I understand, here one Phenyl group migrates (instead of hydride ion) from the carbonyl getting oxidized to that getting reduced.

My question is, what is making the migration of the phenyl group possible?

  • 4
    $\begingroup$ What makes it possible? Ultimately because it is energetically favourable. Plus it is irreversible, so if it occurs there's no way for the product to revert to starting materials $\endgroup$
    – Waylander
    Aug 10, 2021 at 11:15
  • $\begingroup$ Well, as you noticed it's basically a Cannizzaro reaction - reasons are the same, but what you want is rather some kind of rationalisation and should specify which. $\endgroup$
    – Mithoron
    Aug 10, 2021 at 13:22
  • 2
    $\begingroup$ This is known as the benzil-benzilic acid rearrangement. As Waylander noted it's energetically favourable. Phenyl group acts as a group with high migratory aptitude in many other reactions too. One can again question as to what makes the migration of hydride possible in the main Cannizzaro reaction. $\endgroup$
    – TRC
    Aug 10, 2021 at 13:37


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