Question

1. Draw all the possible mono brominated products formed when acetanilide is treated with Br2 in Acetic acid. Identify the major product and Justify your answer.

2. What is the purpose of adding glacial acetic acid in the above reaction?

3. Write the expected HNMR signals for the major product in the above reaction.

4. Electrophilic Bromination of aniline yields a tri bromo product and acetanilide gives only mono brominated product. Explain.

Answer 1

1.

The major product is 4-Bromoacetanilide .

2. Glacial acetic acid is a pure form if acetic acid . If water is present , Br will react with water rather then with aniline . This is why glacial acetic acid is used. Also acetic acid makes bromine less reactive toward aniline . Otherwise acetanilide will produce tri brominated  insted of mono borminated product.

3.

Here A = hydrogen of NH , B = hydrogen of left side of aromatic hydrogen , C = hydrogen of right side of aromatic hydrogen and D = hydrogen of CH₃ after carbonyl group.

4. Electrophilic bromination of aniline yield tri bromo product while acetanilide yield mono bromo product . Mono substituted product of aniline cannot be prepared eiaisily by direct action of a reagent  because amino group of acetanilide is protected by acetyl group while amino group of aniline is not protected.