The reaction of cumene (isopropylbenzene) and acetyl chloride in the presence of aluminum chloride (AlCl3) is known as the Friedel-Crafts acylation reaction. This reaction involves the electrophilic addition of the acetyl chloride to the aromatic ring of cumene, resulting in the formation of a ketone product.

The reaction mechanism can be described as follows:

1. Activation of Acetyl Chloride: Aluminum chloride acts as a Lewis acid and coordinates with the carbonyl oxygen of acetyl chloride, forming an electrophilic species known as the acetyl chloride-aluminum chloride complex. This complex facilitates the departure of the chloride ion, generating a highly reactive acylium ion (CH3C=O+).

2. Electrophilic Addition: The acylium ion then undergoes electrophilic addition to the aromatic ring of cumene. The electron-rich aromatic ring attacks the positively charged acylium ion, forming a new carbon-carbon bond and generating a carbocation intermediate.

3. Rearrangement: The carbocation intermediate undergoes a rearrangement to form a more stable carbocation. This rearrangement involves the migration of a methyl group from the isopropyl group to the positively charged carbon, resulting in the formation of a tertiary carbocation.

4. Nucleophilic Attack: The tertiary carbocation is then attacked by the chloride ion, which acts as a nucleophile, leading to the formation of the final product, 2-methyl-2-phenylpropanone (a ketone).

The overall reaction can be represented as follows:

Cumene + Acetyl Chloride + AlCl3 → 2-Methyl-2-phenylpropanone + HCl + AlCl3

In summary, the reaction of cumene and acetyl chloride in the presence of aluminum chloride undergoes Friedel-Crafts acylation, resulting in the formation of a ketone product through electrophilic addition, rearrangement, and nucleophilic attack.