Resonance in aniline (5 structures) vs anilinium ion (2)ऐनिलीन में अनुनाद (5 संरचनाएँ) बनाम ऐनिलीनियम आयन (2)Resonance in aniline (5 structures) vs anilinium ion (2)
Class 12 Chemistry · Chapter 9 · interactive diagram
Parts and what they mean
- Kekulé structures I and V (no charge separation) (केकुले संरचनाएँ I और V (आवेश पृथक्करण नहीं)) — The lone pair stays on N; only the ring π bonds differ.
- Structures II, III, IV: =N⁺H₂ and a negative charge in the ring (संरचनाएँ II, III, IV: =N⁺H₂ और वलय में ऋण आवेश) — The N lone pair is delocalised into the ring: N becomes positive and the ortho (II, IV) or para (III) carbon negative.
- Curved arrows (वक्र तीर) — Each arrow starts at an electron pair (lone pair or π bond) and ends where the pair goes (a new bond or an atom).
- High electron density at ortho and para positions (ऑर्थो और पैरा स्थितियों पर अधिक इलेक्ट्रॉन घनत्व) — That is why –NH₂ is ortho/para directing and a powerful activating group in electrophilic substitution.
- Anilinium ion C₆H₅N⁺H₃ — two Kekulé structures (ऐनिलीनियम आयन C₆H₅N⁺H₃ — दो केकुले संरचनाएँ) — After protonation N has no lone pair, so no structures like II–IV are possible.
- Why aniline is a weak base (ऐनिलीन दुर्बल क्षारक क्यों है) — More resonance structures → more stability. Aniline (5) is more stabilised than the anilinium ion (2), so its proton acceptability is less than that of ammonia (pKb 9.38 vs 4.75).
Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake