Mechanism of esterification (acid-catalysed)एस्टरीकरण की क्रियाविधि (अम्ल-उत्प्रेरित)Mechanism of esterification (acid-catalysed)

Class 12 Chemistry · Chapter 8 · interactive diagram

Parts and what they mean

• Overall: acid + alcohol ⇌ ester + water (कुल: अम्ल + ऐल्कोहॉल ⇌ एस्टर + जल) — Reversible; conc. H₂SO₄ or HCl gas catalyses it. Removing water or ester as it forms pushes it forward.
• Step 1 — protonation of the carbonyl oxygen (पद 1 — कार्बोनिल ऑक्सीजन का प्रोटॉनीकरण) — Activates the carbonyl carbon towards nucleophilic addition.
• Step 2 — nucleophilic addition of the alcohol (पद 2 — ऐल्कोहॉल का नाभिकस्नेही योग) — The O of R′OH attacks the carbonyl carbon; a tetrahedral intermediate forms.
• Step 3 — proton transfer (पद 3 — प्रोटॉन स्थानांतरण) — Converts an –OH into –OH₂⁺, a much better leaving group.
• Step 4 — elimination of water (पद 4 — जल का विलोपन) — A neutral water molecule leaves, giving the protonated ester.
• Step 5 — loss of H⁺ (पद 5 — H⁺ का निकलना) — Gives the ester and regenerates the H⁺ catalyst. Overall: nucleophilic acyl substitution.

Steps

1. Protonation of the carbonyl oxygen.
2. The alcohol adds to the carbonyl carbon.
3. Proton transfer makes –OH₂⁺.
4. Water leaves.
5. H⁺ is lost: the ester forms.

Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake