Reduction and oxidation of aldehydes and ketonesऐल्डिहाइडों और कीटोनों का अपचयन और ऑक्सीकरणReduction and oxidation of aldehydes and ketones
Class 12 Chemistry · Chapter 8 · interactive diagram
Parts and what they mean
- Aldehyde (ऐल्डिहाइड) — Reduced to a primary alcohol.
- Ketone (कीटोन) — Reduced to a secondary alcohol.
- Primary alcohol (प्राथमिक ऐल्कोहॉल) — NaBH₄, LiAlH₄ or catalytic hydrogenation.
- Secondary alcohol (द्वितीयक ऐल्कोहॉल) — Same reagents as for aldehydes.
- Carbonyl group (aldehyde or ketone) (कार्बोनिल समूह (ऐल्डिहाइड या कीटोन)) — Can be reduced all the way to CH₂.
- Clemmensen reduction: C=O → CH₂ (क्लेमेन्सन अपचयन: C=O → CH₂) — Zinc amalgam + concentrated HCl.
- Hydrazone (हाइड्रेज़ोन) — Formed first with hydrazine.
- Wolff–Kishner reduction: C=O → CH₂ (वोल्फ़–किश्नर अपचयन: C=O → CH₂) — Hydrazone heated with NaOH or KOH in a high-boiling solvent such as ethylene glycol; N₂ is released.
- Tollens’ reagent: ammoniacal silver nitrate (टॉलेन अभिकर्मक: अमोनियामय सिल्वर नाइट्रेट) — Freshly prepared; reaction occurs in alkaline medium.
- Silver mirror + carboxylate anion (रजत दर्पण + कार्बोक्सिलेट ऋणायन) — Ag⁺ is reduced to metallic silver, which coats the tube as a bright mirror. Balanced: atoms and charge (−1 = −1).
- Fehling’s reagent (A: CuSO₄ + B: alkaline Rochelle salt) (फेहलिंग अभिकर्मक (A: CuSO₄ + B: क्षारीय रोशेल लवण)) — Mixed in equal amounts before the test; Cu²⁺ is held as a tartrate complex.
- Red-brown precipitate of Cu₂O (Cu₂O का लाल-भूरा अवक्षेप) — Aliphatic aldehydes give it; aromatic aldehydes (e.g. benzaldehyde) do NOT respond to this test.
- Methyl ketone (CH₃CO– group) (मेथिल कीटोन (CH₃CO– समूह)) — At least one methyl group on the carbonyl carbon is needed (ethanal also qualifies).
- Salt of acid with one carbon less + haloform (एक कम कार्बन वाले अम्ल का लवण + हैलोफॉर्म) — CH₃ becomes CHX₃. With NaOI the yellow precipitate of iodoform (CHI₃) detects CH₃CO– or CH₃CH(OH)– groups.
- 4-Methylpent-3-en-2-one (4-मेथिलपेन्ट-3-ईन-2-ओन) — A methyl ketone that also has a C=C.
- C=C is not affected (C=C प्रभावित नहीं होता) — Hypohalite oxidation leaves a carbon–carbon double bond untouched; chloroform forms.
Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake