Question

In the following compound,

the most favourable site for protonation is:

• A. (ii)
• B. (i)
• C. (v)
• D. (iii)

Answer 1

The correct option is A (ii)

Lone pair electrons on nitrogen (ii, iii, iv) are localised as they are not involved in resonance because conjugate side has $\pi e^{-}$s. The lone pair on (i) facilitates the protonation of (ii) via resonance.