Coupling reactions: azo dyes from benzenediazonium chlorideयुग्मन अभिक्रियाएँ: बेन्ज़ीनडाइऐज़ोनियम क्लोराइड से ऐज़ो रंजकCoupling reactions: azo dyes from benzenediazonium chloride
Class 12 Chemistry · Chapter 9 · interactive diagram
Parts and what they mean
- Benzenediazonium chloride (बेन्ज़ीनडाइऐज़ोनियम क्लोराइड) — Here the diazonium ion acts as an electrophile, and its N₂ is NOT lost.
- Phenol (फ़ीनॉल) — Couples at its para position (in alkaline medium, OH⁻).
- Alkaline medium (OH⁻) (क्षारीय माध्यम (OH⁻)) — Condition used by NCERT for coupling with phenol.
- p-Hydroxyazobenzene — orange dye (p-हाइड्रॉक्सीऐज़ोबेन्ज़ीन — नारंगी रंजक) — C₆H₅N₂⁺Cl⁻ + C₆H₅OH + OH⁻ → C₆H₅–N=N–C₆H₄–OH + Cl⁻ + H₂O (balanced).
- Aniline (ऐनिलीन) — Couples at its para position (in acidic medium, H⁺).
- Acidic medium (H⁺) (अम्लीय माध्यम (H⁺)) — Condition used by NCERT for coupling with aniline.
- p-Aminoazobenzene — yellow dye (p-ऐमीनोऐज़ोबेन्ज़ीन — पीला रंजक) — C₆H₅N₂⁺Cl⁻ + C₆H₅NH₂ → C₆H₅–N=N–C₆H₄–NH₂ + H⁺ + Cl⁻. (NCERT prints "+ Cl⁻ + H₂O" here; by atom count the by-product is HCl.)
- Extended conjugated system (विस्तारित संयुग्मी तंत्र) — Both aromatic rings are joined through –N=N–; such azo compounds are often coloured and used as dyes.
- An electrophilic substitution reaction (एक इलेक्ट्रॉनस्नेही प्रतिस्थापन अभिक्रिया) — The diazonium ion substitutes the H at the para position of phenol/aniline.
Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake