Chemistry - GOC Question with Solution | TestHub
Which one/s is/are true about the above compounds?
Options:(select one or more)
Answer:
Solution:
A. I and III are more basic than II: Pyridine (I) and imidazole (III) are modest Brønsted bases because their nitrogen lone pairs are not part of the aromatic system and can accept a proton. In contrast, pyrrole (II)'s nitrogen lone pair is delocalized to maintain aromaticity, making it a very weak base (protonation occurs only in strong acid, at carbon).
B. In III Nᵃ is more basic than Nᵇ: Nᵇ in imidazole is the basic nitrogen with a lone pair outside the aromatic ring. Nᵃ has its lone pair involved in the aromatic ring system. Therefore, Nᵇ is more basic than Nᵃ. This statement is false.
C. Electrophilic substitution takes place on C2 in II: Pyrrole is highly reactive towards electrophilic substitution, which preferentially occurs at the C2 position due to the formation of a more stable intermediate.
D. All the nitrogens present in (I), (II) and (III) are sp² hybridized: All three compounds are aromatic, which requires all ring atoms, including the nitrogens, to be sp² hybridized to allow for a continuous ring of p-orbitals.