Question

The most likely protonation site in the following molecule is

• A. C-1
• B. C-2
• C. C-3
• D. C-6

Answer 1

Answer: (A)

C-1

Answer 2

Addition of a proton at $C^{1}$ results in the formation of tropylium carbocation (an aromatic species with more stability due to delocalisation of $\pi$ electrons), thus, it is the most reactive site towards protonation.
Addition of proton at any other carbon atom, interupt in the delocalisation of $\pi$ electrons by disturbing planarity of molecules and hence, makes it less stable. Thus, these all are less reactive towards protonation.