Question

Why is para substitution is favoured over ortho in nitration of acetanilide?

Answer 1

✔Under concentrated acidic medium meta is the main product (because of formation of Ar-NH3-plus , strongly meta directing). From my view ortho is less since the attaching of nitronium ion to that position may be more difficult because of steric effect from three hydrogen and less electron density(or more positive nature of ortho carbon).