Chapter 22, Problem 22.35P

Interpretation Introduction

Interpretation:

A mechanism for the reaction of benzene with sulfur dichloride $\left({\text{SCl}}_{\text{2}}\right)$ in the presence of a Friedel–Crafts catalyst like ${\text{AlCl}}_{\text{3}}$ to form diphenyl sulfide is to be proposed.

Concept introduction:

In Friedel–Crafts alkylation reaction, the carbocation is generated from alkyl halide in presence of catalyst like ${\text{AlCl}}_{\text{3}}$. The carbocation formed then acts as an electrophile. The aromatic ring acts as a nucleophile and undergoes electrophilic substitution reaction by attacking the carbocation. Similarly, sulfur dichloride, in presence of a Friedel–Crafts catalyst like ${\text{AlCl}}_{\text{3}}$, forms an electrophile as ${\text{S}}^{+}$ and gets attacked by benzene. As there are two chlorine atoms bonded to sulfur, the reaction occurs twice and forms diphenyl sulfide.