Acetanilide (Protection of $$-\text{NH}_2$$ Group)

Formula / Core Reaction:

$$\text{C}_6\text{H}_5\text{NH}_2 + (\text{CH}_3\text{CO})_2\text{O} \xrightarrow{\text{Pyridine}} \text{C}_6\text{H}_5\text{NHCOCH}_3 + \text{CH}_3\text{COOH}$$

Concept: Nucleophilic acyl substitution of aniline with acetic anhydride in the presence of pyridine yields acetanilide, moderating the activating effect of the $$-\text{NH}_2$$ group via resonance.

Notation / Key Observation:

• $$\text{C}_6\text{H}_5\text{NH}_2$$: Aniline;
• $$(\text{CH}_3\text{CO})_2\text{O}$$: Acetic anhydride (Acetulating agent);
• $$\text{C}_6\text{H}_5\text{NHCOCH}_3$$: Acetanilide (White crystalline solid).