The preparation of 4-bromoacetanilide from acetanilide and bromine can be carried out through electrophilic aromatic substitution. Here is a step-by-step procedure for this reaction:1. Weigh out approximately 2 grams of acetanilide and transfer it to a 250 mL round-bottom flask.2. Add 50 mL of glacial acetic acid to the flask containing acetanilide. Stir the mixture to dissolve the acetanilide completely.3. In a separate container, prepare a solution of bromine by dissolving 1.2 grams of bromine in 5 mL of glacial acetic acid.4. Slowly add the bromine solution to the acetanilide solution in the round-bottom flask, while stirring continuously. The reaction mixture will turn reddish-brown due to the formation of the bromonium ion.5. Heat the reaction mixture on a water bath at 60-70C for about 30 minutes to ensure complete reaction.6. Cool the reaction mixture to room temperature. The product, 4-bromoacetanilide, will precipitate out as yellowish-brown crystals.7. Filter the crystals using vacuum filtration and wash them with cold water to remove any unreacted bromine and acetic acid.8. Recrystallize the product from a suitable solvent, such as ethanol or a mixture of ethanol and water, to obtain pure 4-bromoacetanilide crystals.To determine the purity of the final product, you can use the following techniques:1. Melting point determination: Determine the melting point of the purified 4-bromoacetanilide using a melting point apparatus. Compare the observed melting point with the literature value approximately 165-166C . A sharp melting point close to the literature value indicates a high degree of purity.2. Thin Layer Chromatography TLC analysis: Perform a TLC analysis of the purified 4-bromoacetanilide using an appropriate solvent system e.g., a mixture of hexane and ethyl acetate . Spot the purified product and a reference sample of 4-bromoacetanilide on a TLC plate and develop the plate in the solvent system. Visualize the spots under UV light or by staining with an appropriate reagent e.g., iodine . Compare the Rf values of the purified product and the reference sample. If the Rf values match and only one spot is observed for the purified product, it indicates a high degree of purity.