Why carboxylic acids are stronger acids than phenolsकार्बोक्सिलिक अम्ल फ़ीनॉल से प्रबल अम्ल क्योंWhy carboxylic acids are stronger acids than phenols
Class 12 Chemistry · Chapter 8 · interactive diagram
Parts and what they mean
- Carboxylate structure I (कार्बोक्सिलेट संरचना I) — Negative charge on one oxygen.
- Carboxylate structure II (equivalent) (कार्बोक्सिलेट संरचना II (समतुल्य)) — Same energy as I — charge on the other oxygen. Equivalent structures give large stabilisation.
- Resonance (अनुनाद) — The real carboxylate ion is the hybrid of I and II.
- Charge delocalised over TWO electronegative oxygens (ऋण आवेश दो विद्युतऋणी ऑक्सीजनों पर विस्थानित) — Both C–O bonds have the same length.
- Phenoxide: charge on oxygen (फ़ीनॉक्साइड: आवेश ऑक्सीजन पर) — The only structure with the charge on O.
- Phenoxide: charge on an ortho carbon (फ़ीनॉक्साइड: आवेश ऑर्थो कार्बन पर) — Carbon is less electronegative than oxygen — a less stable structure.
- Phenoxide: charge on the para carbon (फ़ीनॉक्साइड: आवेश पैरा कार्बन पर) — Non-equivalent to the first structure.
- Phenoxide: charge on the other ortho carbon (फ़ीनॉक्साइड: आवेश दूसरे ऑर्थो कार्बन पर) — More structures, but less important ones.
- Charge on carbon = weak stabilisation (कार्बन पर आवेश = दुर्बल स्थायित्व) — Resonance in phenoxide is not as important as in carboxylate (NCERT Exercise 8.20).
- Conclusion (निष्कर्ष) — Carboxylic acids (pKa ≈ 4–5) are more acidic than phenol (pKa 10) and ethanol (pKa ≈ 16).
Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake