p-Nitroacetanilide

Formula / Core Reaction:

$$\text{C}_6\text{H}_5\text{NHCOCH}_3 + \text{HNO}_3 \xrightarrow[\text{288 K}]{\text{conc. } \text{H}_2\text{SO}_4} p\text{-O}_2\text{N-C}_6\text{H}_4\text{-NHCOCH}_3 + o\text{-isomer (minor)}$$

Concept: Nitration of acetanilide with a nitrating mixture ($$\text{HNO}_3 + \text{H}_2\text{SO}_4$$). Protecting the amino group prevents oxidation and directs nitration predominantly to the para-position due to steric hindrance.

Notation / Key Observation:

• Nitrating mixture: Conc. $$\text{HNO}_3$$ + Conc. $$\text{H}_2\text{SO}_4$$ (1:1 ratio);
• p-Nitroacetanilide: Major product (Off-white/Yellowish solid).