Question

What are the limitation of friedel-crafts alkylation?

Answer 1

There are possibilities of carbocation rearrangements when you are trying to add a carbon chain greater than two carbons. The rearrangements occur due to hydride shifts and methyl shifts. For example, the product of a Friedel-Crafts Alkylation will show an iso rearrangement when adding a three carbon chain as a substituent. Also, the reaction will only work if the ring you are adding a substituent to is not deactivated. For a look at substituents that activating or deactivating Benzene Rings.
The three key limitations of Friedel-Crafts alkylation are:

The three key limitations of Friedel-Crafts alkylation are:

Carbocation Rearrangement - Only certain alkylbenzenes can be made due to the tendency of cations to rearrange.
Compound Limitations - Friedel-Crafts fails when used with compounds such as nitrobenzene and other strong deactivating systems.
Polyalkylation - Products of Friedel-Crafts are even more reactive than starting material. Alkyl groups produced in Friedel-Crafts Alkylation are electron-donating substituents meaning that the products are more susceptible to electrophilic attack than what we began with. For synthetic purposes, this is a big dissapointment

Answer 2

Answer:

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Explanation:

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