JEE Main · 2021 · 16 Mar 2021 · Shift 2 · Compounds Containing Nitrogen

Basicity measures how readily the nitrogen lone pair is handed to a proton. In triethylamine and in diethylamine the nitrogen carries only alkyl groups, which release electrons and leave the lone pair fully available, so both are strong bases. One acetyl group draws the lone pair into its carbonyl by resonance, and N-ethylacetamide is accordingly much weaker. In diacetamide the single lone pair is delocalised over two carbonyl groups at once, which strips the nitrogen most thoroughly and even makes the $\mathrm{N}-\mathrm{H}$ acidic. The least basic is diacetamide, $(\mathrm{C}{\mathrm{H}}_3\mathrm{CO}{)}_2\mathrm{NH}$.