Question

How can the following conversion be carried out:
Aniline to bromobenzene

Answer 1

Hint: Tho convert aniline into bromobenzene we need to form the diazonium salt. The conversion of aniline to bromobenzene occurs in 2 steps out of which the second step of the reaction is known as the Sandmeyer reaction. The Sandmeyer is considered as the radical nucleophilic aromatic substitution reaction.

Complete step-by-step answer:So to convert aniline into bromobenzene we need to follow two steps. In the first step we will react the aniline with \[NaN{{O}_{2}}/HCl\]to form the intermediate compound. The intermediate compound is the diazonium salt known as the benzene diazonium chloride. The range of the temperature during the formation of diazonium salt should be between \[{{0}^{o}}C-{{5}^{o}}C\]. In the next step we will react to the benzene diazonium salt with the \[CuBr/HCl\]. This process of the diazonium salt with the \[CuBr/HCl\]is known as Sandmeyer reaction. This reaction is the example of the radical nucleophilic aromatic substitution reaction. So look at the following steps and reaction for understanding:
Reaction of aniline with the \[NaN{{O}_{2}}/HCl\]to form benzene diazonium chloride:
\[{{C}_{6}}{{H}_{5}}N{{H}_{2}}+2HCl+NaN{{O}_{2}}\xrightarrow{{{0}^{o}}C-{{5}^{o}}C}{{C}_{6}}{{H}_{5}}{{N}_{2}}^{+}C{{l}^{-}}+NaCl+2{{H}_{2}}O\]
Now the benzene diazonium chloride will be reacted with \[CuBr/HCl\] to form bromobenzene:
\[{{C}_{6}}{{H}_{5}}{{N}_{2}}^{+}C{{l}^{-}}\xrightarrow{CuBr/HCl}{{C}_{6}}{{H}_{5}}Br\]
The formation of bromobenzene takes place from aniline.

Note:There are various types of Sandmeyer reactions in which the reaction of the benzene diazonium chloride takes place with CuCl, CuBr and CuCN to form the product such as chlorobenzne, bromobenzene and benzonitrile respectively. In the Sandmeyer reaction for converting the compound to chlorobenzene the CuCl is used as the reagent. The Sandmeyer reaction helps in forming the various compounds such as benzonitrile.