Alcohols, Phenols and Ethers Class 12: Complete Guide, Reactions & Formula Sheet with Free PDF Download (JEE & NEET)
Alcohols, Phenols & Ethers Class 12 Chemistry — Competishun
Alcohols, Phenols and Ethers Class 12: Complete Guide, Reactions & Formula Sheet with Free PDF Download (JEE & NEET)
Alcohols, Phenols and Ethers is one of the most important organic chemistry chapters in Class 12, and a favourite for JEE and NEET. It is packed with preparation methods, reactions and named reactions, so a clear, organised guide makes a huge difference at revision time.
This complete guide brings the whole chapter together: classification, preparation, physical and chemical properties, the key name reactions, the acidity order and the distinction tests, all in one place. Download the free PDF below and keep it handy for quick revision.
Download the Alcohols, Phenols & Ethers Complete PDF
Get preparation, reactions, name reactions, acidity order and distinction tests in one clean PDF, free. Perfect for Class 12, JEE and NEET revision.
Download Free PDFClassification & General Formulas
| Class | Functional Group | General Formula |
|---|---|---|
| Alcohol | -OH on an alkyl carbon | R-OH |
| Phenol | -OH on a benzene ring | Ar-OH (C₆H₅-OH) |
| Ether | -O- between two carbons | R-O-R' |
| Alcohols are further classified as primary (1°), secondary (2°) and tertiary (3°) by the carbon bearing the -OH. | ||
Preparation Methods
| Compound | Method | Key Point |
|---|---|---|
| Alcohol | Acid-catalysed hydration of alkene | Markovnikov addition |
| Alcohol | Hydroboration-oxidation | Anti-Markovnikov, gives 1° alcohol |
| Alcohol | Reduction of aldehydes/ketones | Aldehyde → 1°, ketone → 2° |
| Alcohol | Grignard reagent + carbonyl | Versatile C-C bond method |
| Phenol | From cumene (industrial) | Also gives acetone as by-product |
| Phenol | From diazonium salt / haloarene / benzene sulphonic acid | Standard lab routes |
| Ether | Williamson synthesis | R-X + R'-ONa → R-O-R' (SN2, use 1° R-X) |
| Williamson synthesis is the single most important preparation to remember for ethers. | ||
Physical Properties
- Hydrogen bonding: Alcohols and phenols form H-bonds, giving high boiling points
- Boiling point order: Alcohols and phenols > ethers (ethers cannot self H-bond)
- Solubility: Lower alcohols are fully miscible in water, solubility drops as the alkyl chain grows
- Phenol: Slightly soluble, weakly acidic, higher boiling than corresponding alcohol
Chemical Reactions of Alcohols
| Reaction | Product / Note |
|---|---|
| With sodium | 2R-OH + 2Na → 2R-ONa + H₂↑ |
| With HX | R-OH + HX → R-X + H₂O (reactivity 3° > 2° > 1°) |
| Esterification | R-OH + R'COOH ⇌ R'COOR + H₂O (acid catalyst) |
| Dehydration | Alcohol → alkene (conc. H₂SO₄, 443 K); 3° > 2° > 1° |
| Oxidation of 1° alcohol | → aldehyde → carboxylic acid |
| Oxidation of 2° alcohol | → ketone |
| Oxidation of 3° alcohol | resistant (no easy oxidation) |
| Reaction with active metals like sodium shows the acidic nature of the -OH hydrogen. | |
Chemical Reactions of Phenols
| Reaction | Product / Note |
|---|---|
| Acidic nature | Forms phenoxide with NaOH (more acidic than alcohol) |
| Electrophilic substitution | Nitration, halogenation, sulphonation (ortho/para directing) |
| Bromination | With bromine water → 2,4,6-tribromophenol |
| Kolbe's reaction | Phenol → salicylic acid (o-hydroxybenzoic acid) |
| Reimer-Tiemann reaction | Phenol + CHCl₃ + NaOH → salicylaldehyde |
| Reaction with FeCl₃ | Violet colour (test for phenol) |
| Phenol is ortho and para directing in electrophilic aromatic substitution because -OH is activating. | |
Chemical Reactions of Ethers
| Reaction | Product / Note |
|---|---|
| Cleavage by HX (HI, HBr) | R-O-R' + HX → R-X + R'-OH (excess HX → two halides) |
| Aromatic ether cleavage | Anisole + HI → phenol + CH₃I |
| Electrophilic substitution | Aromatic ethers undergo ortho/para substitution (-OR activating) |
| In ether cleavage, the smaller/more stable alkyl group generally leaves as the halide. | |
Acidity Order (Very Important)
Phenol is more acidic than alcohol because the phenoxide ion formed after losing H⁺ is stabilised by resonance into the benzene ring. Electron-withdrawing groups (like -NO₂) increase phenol's acidity, while electron-donating groups (like -CH₃) decrease it.
Important Name Reactions
| Name Reaction | What It Does |
|---|---|
| Williamson Synthesis | Prepares ethers from alkyl halide + alkoxide (SN2) |
| Kolbe's Reaction | Phenol → salicylic acid using CO₂ and NaOH |
| Reimer-Tiemann Reaction | Phenol → salicylaldehyde using CHCl₃ and NaOH |
| Lucas Test | Distinguishes 1°, 2° and 3° alcohols |
| Victor Meyer Test | Distinguishes 1°, 2° and 3° alcohols (colour test) |
| These name reactions are directly asked in JEE and NEET almost every year. | |
Distinction Tests
| Test | Result |
|---|---|
| Lucas test (3° alcohol) | Immediate turbidity |
| Lucas test (2° alcohol) | Turbidity in ~5 minutes |
| Lucas test (1° alcohol) | No turbidity at room temperature |
| Alcohol vs Phenol | Phenol gives violet colour with neutral FeCl₃, alcohol does not |
| Lucas test works because carbocation stability is 3° > 2° > 1°, so tertiary reacts fastest. | |
Key Points to Remember
- Acidity: Carboxylic acid > phenol > water > alcohol
- Oxidation: 1° → aldehyde → acid, 2° → ketone, 3° resists oxidation
- Dehydration & HX reactivity: 3° > 2° > 1°
- Ethers: Made by Williamson, cleaved by HI/HBr
- Tests: Lucas for 1°/2°/3° alcohols, FeCl₃ for phenol
Common Mistakes to Avoid
- Phenol vs alcohol acidity: Phenol is more acidic, remember the resonance reason
- Markovnikov confusion: Hydration is Markovnikov, hydroboration is anti-Markovnikov
- Williamson halide choice: Use primary alkyl halide to avoid elimination
- Oxidation of 3° alcohol: It resists normal oxidation, do not force a product
Why This Chapter Matters for JEE & NEET
- High weightage: Alcohols, Phenols and Ethers appears every year in JEE and NEET
- Reaction based: Rewards clear memory of preparations and name reactions
- Links other chapters: Connects to aldehydes, ketones and carboxylic acids
- Scoring with revision: A good summary sheet makes it fast and reliable
How to Use This Guide
- Group the reactions: Study alcohol, phenol and ether reactions separately
- Master name reactions: Williamson, Kolbe and Reimer-Tiemann are must-know
- Memorise the acidity order: It is asked directly and used in reasoning
- Revise from the PDF: Skim it before every chemistry test and mock
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