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In Hoffmann's rearrangement of acid amide...the OH from the basic medium attacked the H ..now my question is...isn't the carbonyl carbon more acidic as it's surrounded by 2 electronegative elements?

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  • $\begingroup$ I suppose here $\ce{OH-} $ acts as a base and not as nucleophile. $\endgroup$
    – Suraj S
    May 14, 2017 at 11:19
  • $\begingroup$ why not a nucleophile then? $\endgroup$
    – Salma
    May 14, 2017 at 11:23
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    $\begingroup$ $\ce{OH-}$ cannot act as a nucleophile here, since in that case, leaving ground would be $\ce{NH2-}$, which is stronger than hydroxide. $\endgroup$ May 14, 2017 at 12:14
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    $\begingroup$ The arrows should be equilibria ones and yes, the hydroxide will probably act as a nucleophile but it's a product dead-end, shuttling around in equilibrium $\endgroup$
    – Beerhunter
    Jun 12, 2017 at 22:26

1 Answer 1

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You are right, the OH- ion can indeed act as a nucleoplhile attacking the unsaturated carbonyl group giving rise to a hemi acetal type of complex (with an amino group instead of an OH group). This is similarly unstable and tends to form back the initial carbonyl compound by the elimination of the OH- group. The NH2- cannot be the leaving group here because it is a bad leaving group as compared to the OH- group. Hence the OH- prefers to attack as a base instead and remove the acidic hydrogem from the amide.

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