Base strength here depends on how freely the nitrogen lone pair is offered to a proton. In benzylamine, CX6HX5CHX2NHX2, the NHX2 hangs off an sp3CHX2 that insulates it from the ring, so the lone pair stays localised and fully basic. In aniline and in N-methylaniline the lone pair is drawn into the aromatic ring and so is less available, while the ortho-substituted amine suffers steric crowding. Benzylamine therefore stands out as the strongest base.
JEE Main · 2004 · 24 Apr 2004 · Offline · Single correct option