# What is the product from the reaction of 4-cyclohexylbenzene with fuming sulfuric acid?

Jan 26, 2017

I would expect the product to be 4-cyclohexylbenzenesulfonic acid.

#### Explanation:

Sulfonation of a benzene ring is a standard electrophilic aromatic substitution reaction.

It is easily carried out by gentle warming of the aromatic compound with fuming sulfuric acid at 40 °C for about 30 min.

The electrophile is probably the protonated ${\text{SO}}_{3}$.

The mechanism is as shown below for benzene.

(From StudyBlue)

The cyclohexyl group is an ortho/para director.

Its bulk should hinder attack at the ortho position.

I predict that the major product will be 4-cyclohexylbenzenesulfonic acid.

(Structure by OPSIN)