Acetanilide can be converted into 4-bromoacetanilide using bromine as a reagent through a process called electrophilic aromatic substitution. In this reaction, bromine acts as an electrophile, and acetanilide acts as a nucleophile. The mechanism of this chemical synthesis reaction involves the following steps:1. Formation of the electrophile: Bromine Br2 reacts with a Lewis acid catalyst, such as aluminum bromide AlBr3 or iron III bromide FeBr3 , to form a highly electrophilic bromonium ion Br+ . Br2 + AlBr3 Br+ + AlBr4-2. Attack of the nucleophile: The aromatic ring of acetanilide acts as a nucleophile and attacks the electrophilic bromonium ion Br+ , forming a sigma complex also known as an arenium ion . This step results in the temporary loss of aromaticity.3. Deprotonation: A base, which could be the AlBr4- or another molecule of acetanilide, abstracts a proton from the sigma complex, restoring the aromaticity of the ring and forming 4-bromoacetanilide.4. Regeneration of the catalyst: The Lewis acid catalyst is regenerated in the process, allowing it to be used again in the reaction. HAlBr4- AlBr3 + HBrOverall, the reaction can be represented as: Acetanilide + Br2 4-Bromoacetanilide + HBrIt is important to note that the amide functional group in acetanilide is a meta-directing group, meaning it directs the electrophilic substitution to the meta position. However, the reaction can still occur at the para position 4-bromoacetanilide due to the steric hindrance at the ortho positions. To increase the selectivity for the para product, the reaction can be carried out at low temperatures and with a slight excess of bromine.