Rank the nitrogen atoms in chloroquine, shown below, in order of decreasing basicity, putting the most basic nitrogen atom first.

Question

Quizplus · Accepted Answer

In chloroquine molecule, nitrogen atoms are basic due to lone pair of electrons present on them. The basicity of nitrogen atom depends on its ability to donate lone pair of electrons. Nitrogen atom with the highest electron density or the most exposed lone pair of electrons will be most basic. 
Among the three nitrogen atoms in chloroquine, N3 is most basic because it is attached to an electron withdrawing group (-Cl) which makes it more electron-rich than other two nitrogen atoms. N1 is less basic than N3 because it shares its lone pair of electrons with three other atoms. N2 is least basic because it is the farthest away from the electron withdrawing group. 
Therefore, the order of basicity is N3 > N2 > N1. Thus, the correct answer is choice (C).

Rank the Nitrogen Atoms in Chloroquine, Shown Below, in Order