A question in my book asks:

In the reaction:

enter image description here

The intermediate(s) is/are?

The correct answers are given as

enter image description here

However, as per my knowledge, compound (b) does not appear in the reaction mechanism. Is this an error in the book or do I know the wrong mechanism?

Correct mechanism according to me:

enter image description here

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    $\begingroup$ Can you give the reference for the book? $\endgroup$ Mar 26, 2021 at 5:18
  • $\begingroup$ Also, (b) and (c) are not intermediates, they are products. $\endgroup$ Mar 26, 2021 at 5:55
  • $\begingroup$ @Mathew If (IV) is the product then (b) and (c) could be intermediates. $\endgroup$
    – S R Maiti
    Mar 26, 2021 at 16:20
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    $\begingroup$ @Shoubhik R Maiti: In that way, (I) and (III) are also intermediates. But they were not included in the answer. That's why my comment. In my experience, (II)-(IV) are in the product mixture, in which (IV) predominates. $\endgroup$ Mar 26, 2021 at 16:56
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    $\begingroup$ @Hridai Khurana: I understand now. Yes, your mechanism is acceptable. It's believed to be step by step addition of $\ce{Br2}$ to the ring. However, I doubt ipso addition of $\ce{Br2}$ (structure (b)) exists because of inductive effect of $\ce{Br}$ (it is not in your mechanism). $\endgroup$ Mar 26, 2021 at 19:23

1 Answer 1


The correct answer per my checks is B, however I stand for correction. Since the solvent is a polar solvent, the OH of the solvent will abstract the H of the OH on the phenol. Making the phenol a phenolic oxide PhO. Which will activate or the electrons on the O of the phenoxide will be pushed to the Ortho and the Para position on the ring, making them more activated hence the formation of a trisubstituted ring.


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