Why is only 4-bromoacetanilide created mainly from a bromination of acetanilide?

Answer 1

The Acetanilide is a benzene with a acetamido group attached to it. The acetamido group is electron donating and therefore it directs other substituents to the ortho and para positions. The acetamido group is also a very large group and the ortho position is right besides the acetamido group. This creates steric hindrance from bromine from getting to the ortho position and therefore only para-bromoacetanilide or 4-bromoacetanilide is created mainly from a bromination of acetanilide.

Answer 2

4-bromoacetanilide is mainly formed from the bromination of acetanilide because the bromine atom primarily substitutes the para position on the benzene ring due to steric hindrance, making it the major product. The meta and ortho positions are less favorable due to destabilizing interactions with the amide group.