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According to our lab manual:

In general, Friedel–Crafts alkylation is not employed to make monoalkyl benzene derivatives because of the polysubstitution.

But our professor told us that while we are doing this experiment, polysubstitution is quite impossible.

Phenol + t-butyl chloride (AlCl3 catalyst)--> para-t-butylphenol + HCl

I know the when the electrophile is bigger and amounts are exact, it is harder for polysubstitution to occur but not impossible.

So I wonder if the reason why she said that, is about chemical properties of the reagents (like being activating) or is it something about the method we use in the experiment?

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    $\begingroup$ Phenol first forms a complex with AlCl3 so the ortho sites are hindered for approach by a large electrophile $\endgroup$
    – Waylander
    Apr 28 '21 at 10:39
  • $\begingroup$ @Waylander That really makes sense thank you! $\endgroup$
    – O.Ceren
    Apr 28 '21 at 10:56

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