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My textbook doesn't mention the conditions required for an ipso attack to occur. It just describes some examples where groups like $\ce{-C(CH3)}$ and $\ce{-SO3H}$ are replaced by $\ce{Br}$ using reagents like $\ce{Br2}$/$\ce{AlCl3}$. Can someone describe the required conditions in detail?

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In ipso substitution first step is usually attack of the nucleophilic species at the ipso carbon of the aromatic ring (the carbon bearing the leaving group in this case).

Scheme 1 enter image description here

The first step is followed by elimination of the leaving group and regeneration of the aromatic ring.

Scheme 2

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This mechanism greatly resembles the tetrahedral mechanism . The attacking species forms a bond with the substrate, giving an intermediate, such as 1, and then the leaving group departs. We refer to this mechanism as the SNAr mechanism.The reaction between 2,4,6-trinitrophenetole and methoxide ion involves ipso substitution.Intermediates of this type are stable salts, called Meisenheimer or Meisenheimer–Jackson salts,7 and many more have been isolated .

Scheme 3

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In the reaction of dinitro compound enter image description here with piperidine,same ipso substitution operates.

Scheme 4

In the reaction between picryl chloride and hydroxyl ions same ipso substitution operates.

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Ref

1.MARCH’S ADVANCED ORGANIC CHEMISTRY REACTIONS, MECHANISMS,AND STRUCTURE SIXTH EDITION ,Michael B. Smith ,Jerry March

2.Organic Chemistry, Volume 1, 6/E By Finar

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