Question

Both the acetamido (-NHCOCH3) and bromo (-Br) substituents are ortho, para directors. Even though the acetamido group is much larger than the bromo group, the -Cl is still introduced next to the acetamido group in spite of the greater steric hinderance at this site. Why?

Answer 1

Answer:

Explanation has been given below

Explanation:

• Attachment of -Cl group at ortho position to acetamido group can be explained in terms of hydrogen bonding formation.
• A hydrogen bonding can be formed between proton attached with N atom in acetamido group and Cl atom at ortho position. This leads to a formation of a stable 5-membered ring structure.
• Hence ortho substitution by Cl is favorable process.
• There is no hydrogen bonding possible between Br and Cl atom in ortho position. Therefore Cl prefers para position to avoid steric hindrance.
• Structure of hydrogen bonded structure has been shown below.