Reactions of carboxylic acids: O–H and C–OH cleavageकार्बोक्सिलिक अम्लों की अभिक्रियाएँ: O–H और C–OH विदलनReactions of carboxylic acids: O–H and C–OH cleavage
Class 12 Chemistry · Chapter 8 · interactive diagram
Parts and what they mean
- With electropositive metals (विद्युतधनी धातुओं के साथ) — Like alcohols, acids evolve hydrogen.
- Sodium carboxylate + hydrogen gas (सोडियम कार्बोक्सिलेट + हाइड्रोजन गैस) — Balanced: 2 : 2 → 2 : 1.
- With alkalies (क्षारों के साथ) — Salt formation, like phenols.
- Salt + water (लवण + जल) — Neutralisation.
- With hydrogencarbonate (a weak base) (हाइड्रोजनकार्बोनेट (दुर्बल क्षारक) के साथ) — Phenols do NOT do this — so it is the test for the –COOH group.
- Brisk effervescence of CO₂ (CO₂ की तीव्र बुदबुदाहट) — Distinguishes benzoic acid from phenol (NCERT Exercise 8.13 iii).
- Dissociation in water (जल में वियोजन) — Carboxylic acids are weak acids: the equilibrium lies mostly to the left.
- Resonance-stabilised carboxylate + hydronium ion (अनुनाद-स्थायी कार्बोक्सिलेट + हाइड्रोनियम आयन) — The stability of RCOO⁻ decides the acid strength.
- Acid dissociation constant (अम्ल वियोजन स्थिरांक) — Ka = Keq[H₂O]. Smaller pKa → stronger acid.
- Two molecules of acid (अम्ल के दो अणु) — Heated with a mineral acid such as H₂SO₄ or with P₂O₅.
- Acid anhydride (अम्ल ऐनहाइड्राइड) — e.g. 2CH₃COOH → (CH₃CO)₂O + H₂O (ethanoic anhydride).
- Esterification (एस्टरीकरण) — With alcohols or phenols; conc. H₂SO₄ or HCl gas catalyst.
- Ester + water (एस्टर + जल) — Reversible (see the mechanism card).
- With phosphorus pentachloride (फ़ॉस्फ़ोरस पेंटाक्लोराइड के साथ) — –OH is replaced by –Cl.
- Acyl chloride + POCl₃ + HCl (ऐसिल क्लोराइड + POCl₃ + HCl) — POCl₃ (a liquid) must be separated from the product.
- With phosphorus trichloride (फ़ॉस्फ़ोरस ट्राइक्लोराइड के साथ) — Three acid molecules per PCl₃.
- Acyl chloride + phosphorous acid (ऐसिल क्लोराइड + फ़ॉस्फ़ोरस अम्ल) — H₃PO₃ remains in the mixture.
- With thionyl chloride (preferred) (थायोनिल क्लोराइड के साथ (वरीय)) — The other two products are gases.
- Acyl chloride + SO₂↑ + HCl↑ (ऐसिल क्लोराइड + SO₂↑ + HCl↑) — Gases escape, so purification of RCOCl is easy.
- With ammonia (अमोनिया के साथ) — First an acid–base reaction.
- Ammonium ethanoate (अमोनियम एथेनोएट) — Heated strongly, it loses water.
- Ethanamide (acetamide) (एथेनामाइड (ऐसीटामाइड)) — An amide. Similarly benzoic acid → benzamide; phthalic acid → phthalimide on strong heating.
Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake