See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Basic Strength Order Analysis To determine basicity, evaluate the availability and stability of the lone pair on nitrogen. ## Compound Analysis: **Compound (1): $p$-methoxybenzamidine** - $OCH_3$ is an electron-donating group (EDG) - Increases electron density on the guanidinium nitrogen - Enhances basicity significantly **Compound (2): $p$-cyanobenzamidine** - $CN$ is a strong electron-withdrawing group (EWG) - Decreases electron density on the nitrogen - Reduces basicity substantially **Compound (3): Benzamide ($C_6H_5CONH_2$)** - The carbonyl ($C=O$) is directly attached to nitrogen - Withdraws electron density through resonance: lone pair delocalizes into $\pi^*$ orbital - Significantly reduces basicity **Compound (4): Phthalimide (indole-1,3-dione)** - Two carbonyl groups delocalize the lone pair extensively - Highly resonance-stabilized (cyclic imide) - Lowest basicity due to maximum electron withdrawal ## Basicity Order: $$\boxed{1 > 2 > 3 > 4}$$ **Reasoning:** EDGs increase basicity; EWGs and conjugation with carbonyls decrease it. Compound (1) has the most basic nitrogen due to EDG activation, while compound (4) has the least due to dual carbonyl deactivation. **Answer: (a)**