August 24, 2019, 02:10:45 PM
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Topic: Why does pyridine does not undergo Friedel craft alkylation?  (Read 133 times)

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Offline AussieKenDoll

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I think it is because the presence of the electronegative N atom in the ring deactivates it toward the reaction with electrophiles. but I am not sure, can you please explain the answer?

Offline hollytara

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Re: Why does pyridine does not undergo Friedel craft alkylation?
« Reply #1 on: July 17, 2019, 12:14:23 PM »
1.  Yes, the N deactivates.

But

2.  The lone pair on the N as nucleophile/base plays havoc with the other reagents.  The Lewis Acid catalyst prefers the pyridine lone pair to the haloalkane reactant, and when complexed the pyridine is even MORE deactivated.  The haloalkane reactant can do SN1/SN2 chemistry with the pyridine to make pyridinium as a side reaction - and the pyridinium is also more deactivated. 

There are other strategies to allow pyridine alkylation,

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