Question

Propose products (if any) and mechanisms for the following AICI₃-catalyzed reactions:

⦁ chlorocyclohexane with benzene

⦁ methyl chloride with anisole

⦁ 3-chloro-2,2-dimethylbutane with isopropylbenzene

Short answer

Friedelcrafts alkylation comes under the category of electrophilic aromatic substitution. The alkyl cation functions as an electrophile in this reaction. The aromatic proton is substituted with an alkyl group in this reaction. The reaction takes place in the presence of a lewis acid like AICI₃ and FeCl₃.

Step-by-step solution

Friedelcrafts alkylation

Friedelcrafts alkylation comes under the category of electrophilic aromatic substitution. The alkyl cation functions as an electrophile in this reaction. The aromatic proton is substituted with an alkyl group in this reaction. The reaction takes place in the presence of a lewis acid like AICI₃ and FeCl₃.

(a) Mechanism for the reaction of cyclohexane with benzene

(a)The AICI₃ catalyzed mechanism comprises three steps: The first step is the formation of carbocation. This is followed by the formation of sigma complex through electrophilic attack. The next step is the loss of proton to produce the alkylated product.

The mechanism of the reaction can be given as:

Mechanism of chlorocyclohexane with benzene

(b) Mechanism for the reaction of methyl chloride with anisole

In the reaction of methyl chloride with anisole, the ortho isomer and para isomer are formed by the AICI₃ catalyzed mechanism. The first step is the formation of carbocation. This is followed by the formation of sigma complex through electrophilic attack. The next step is the loss of proton to produce the alkylated product.

The ortho isomer can be given as:

Mechanism for the reaction of methyl chloride with anisole

The para isomer can also be formed by the similar mechanism.

(c) Mechanism for the reaction of 3-chloro-2,2-dimethylbutane with isopropylbenzene  

In the reaction of 3-chloro-2,2-dimethylbutane with isopropylbenzene, 3-chloro-2,2-dimethylbutane reacts with AICI₃ to generate a carbocation intermediate. This intermediate further reacts with isopropylbenzene to form the final product. The major product is a para isomer and small amounts of the ortho isomer might be produced, as the steric interactions do not encourage this electrophile’s path. The reaction can be given as:

Mechanism for the reaction of 3-chloro-2,2-dimethylbutane with isopropylbenzene