Benzene was treated with isopropyl chloride in the presence of aluminum trichloride under conditions that favor dialkylation. draw the major product (s) expected from this reaction.

The reaction of benzene with an alkyl chloride and aluminum trichloride is called a Friedel-Crafts alkylation. The aluminum trichloride is a lewis acid that reacts with the alkyl chloride, and this converts the alkyl group into a very good electrophile. The overall reaction is an electrophilic aromatic substitution. A pi bond of the benzene ring will attack the electrophile as a nucleophile and form a new carbon-carbon bond. The result is a monosubstituted isopropyl group on the benzene ring.

However, we are told that the conditions are set up to encourage dialkylation. The isopropyl group is a group that donates electron density through induction. Therefore, it is an ortho - and para-directing group. This means that once one isopropyl group is substituted on to the benzene ring, the second substitution will be favoured in the ortho - and para-positions. In this instance, the major product is the 1,4-disubstituted product. The reason being is that the isopropyl groups are very bulky, and the steric hindrance of having two isopropyl groups adjacent leads to a small amount of this product being formed.

There will also be trace amounts of the meta-substituted product, but the 1,4 - and 1,2-substituted products are more favoured.