Question

Draw a stepwise mechanism for the sulfonation of an alkyl benzene such as A to form a substituted benzenesulfonic acid B. Treatment of B with base forms a sodium salt C that can be used as a synthetic detergent to clean away dirt (see Problem 3.22).

Short answer

The reactions in which the hydrogen atom of the benzene ring is replaced by a sulfonic acid functional group$\left({\mathbf{SO}}_{\mathbf{3}}\mathbf{H}\right)$ .

Step-by-step solution

Aromatic sulphonation reaction

The reactions in which the hydrogen atom of the benzene ring is replaced by a sulfonic acid functional group$\left({\mathbf{SO}}_{\mathbf{3}}\mathbf{H}\right)$ .

Formation of SO3+H  using  H2SO4

The generation of${}^{\mathbf{+}}\mathbf{SO}_{\mathbf{3}}\mathbf{H}$from ${\mathbf{H}}_{\mathbf{2}}{\mathbf{SO}}_{\mathbf{4}}$is shown below.

Sulfonation of the given compound

The mechanism for the sulfonation of A is provided below