What product do you predict from the reaction of \(\mathrm{SCl}_{2}\) with benzene in the presence of \(\mathrm{AlCl}_{3}\) ? What product results if diphenyl ether is treated with \(\mathrm{SCl}_{2}\) and \(\mathrm{AlCl}_{3}\) ?

The reaction of benzene with \(\mathrm{SCl}_{2}\) in the presence of \(\mathrm{AlCl}_{3}\) is an electrophilic aromatic substitution reaction. In this reaction, a hydrogen atom on the benzene ring is replaced by an electrophile, generated from the reaction between \(\mathrm{SCl}_{2}\) and \(\mathrm{AlCl}_{3}\).

The reaction between \(\mathrm{SCl}_{2}\) and the Lewis acid catalyst \(\mathrm{AlCl}_{3}\) generates a strong electrophile, \(\mathrm{SCl}^{+}\), and a byproduct, \(\mathrm{AlCl}_{4}^{-}\): \(\mathrm{SCl}_{2} + \mathrm{AlCl}_{3} \rightarrow \mathrm{SCl}^{+} + \mathrm{AlCl}_{4}^{-}\)

The generated electrophile, \(\mathrm{SCl}^{+}\), reacts with the benzene ring to form a sigma complex (also known as the arenium ion). This intermediate then deprotonates to regenerate the aromaticity, and the final product is formed. The overall substitution reaction can be depicted as: Benzene + \(\mathrm{SCl}^{+} \rightarrow\) Chlorobenzene + \(\mathrm{HSCl}\)

In the second reaction, we need to determine the product formed when diphenyl ether is treated with \(\mathrm{SCl}_{2}\) and \(\mathrm{AlCl}_{3}\). Diphenyl ether can react with \(\mathrm{SCl}_{2}\) and \(\mathrm{AlCl}_{3}\) in a similar electrophilic aromatic substitution reaction as the one described in Steps 2 and 3. However, since diphenyl ether has an oxygen atom that can coordinate with the Lewis acid, \(\mathrm{AlCl}_{3}\), the reaction proceeds through a slightly different electrophilic species and leads to a different product. The oxygen atom in diphenyl ether coordinates with \(\mathrm{AlCl}_{3}\) to form a complex, which makes one of the phenyl rings more susceptible to electrophilic attack. The \(\mathrm{SCl}_{2}\) reacts with this complex to form a new electrophilic species (\(\mathrm{ROSCl}^{-}\)). The final product is then obtained via a similar electrophilic substitution and deprotonation sequence as described previously. The steps can be summarized as follows: Diphenyl Ether + \(\mathrm{AlCl}_{3} \rightarrow\) Diphenyl Ether-\(\mathrm{AlCl}_{3}\) Complex Diphenyl Ether-\(\mathrm{AlCl}_{3}\) Complex + \(\mathrm{SCl}_{2} \rightarrow\) Diphenyl Ether-\(\mathrm{ROSCl}^{-}\) Complex Diphenyl Ether-\(\mathrm{ROSCl}^{-}\) Complex \(\rightarrow\) Phenylbenzo[b]thiophene-1-oxide (Final Product) In conclusion, the product formed from the reaction of benzene with \(\mathrm{SCl}_{2}\) in the presence of \(\mathrm{AlCl}_{3}\) is chlorobenzene, and the product formed from the reaction of diphenyl ether with \(\mathrm{SCl}_{2}\) and \(\mathrm{AlCl}_{3}\) is phenylbenzo[b]thiophene-1-oxide.