Question

A student plans a two-step synthesis of 1-ethyl-3-nitrobenzene from benzene. The first step is nitration of benzene to give nitrobenzene, and the second step is a Friedel-Crafts alkylation using CH3CH2Cl and AlCl3. The plan is flawed because: A : When the alkyl halide interacts with AlCl3, the resulting carbocation can rearrange before it has a chance to react with the aromatic ring. B : Nitrobenzene is too deactivated (by the nitro group) to undergo a Friedel-Crafts alkylation. C : The nitro group will direct the incoming alkyl group para position, rather than to the meta position. D : A blocking group is required to achieve this synthesis.

Answer 1

Answer:

Nitrobenzene is too deactivated (by the nitro group) to undergo a Friedel-Crafts alkylation.

Explanation:

The benzene ring in itself does not easily undergo electrophilic substitution reaction. Some groups activate or deactivate the benzene ring towards electrophilic substitution reactions.

-NO2 ia a highly deactivating substituent therefore, Friedel-Crafts alkylation of nitrobenzene does not take place under any conditions.

This reaction scheme is therefore flawed because Nitrobenzene is too deactivated (by the nitro group) to undergo a Friedel-Crafts alkylation.