Complete Summary and Solutions for Alcohols, Phenols and Ethers – NCERT Class XII Chemistry Part II, Chapter 7 – Nomenclature, Properties, Preparation, and Reactions
Detailed summary and explanation of Chapter 7 'Alcohols, Phenols and Ethers' from the NCERT Class XII Chemistry Part II textbook, covering nomenclature, methods of preparation, physical and chemical properties, and important reactions of alcohols, phenols, and ethers, along with illustrative examples and all NCERT questions and solutions.
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Alcohols, Phenols and Ethers
Chapter 7: Chemistry - Ultimate Study Guide | NCERT Class 12 Notes, Questions, Derivations & Quiz 2025
Full Chapter Summary & Detailed Notes - Alcohols, Phenols and Ethers Class 12 NCERT
Overview & Key Concepts
- Chapter Goal: Understand nomenclature, preparations, properties, reactions of alcohols, phenols, ethers. Exam Focus: Reactions, mechanisms, distinctions; 2025 Updates: Industrial apps (e.g., ethanol in fuels, phenols in antiseptics). Fun Fact: Ethanol in spirit. Core Idea: -OH group variations. Real-World: Detergents, fragrances. Expanded: All subtopics point-wise with evidence (e.g., Table 7.1 names), examples (e.g., Markovnikov), debates (phenol acidity).
- Wider Scope: From classification to functional group reactions; sources: Text, figures (7.1), tables.
- Expanded Content: Include mechanisms, diagrams; links (e.g., to haloalkanes); point-wise breakdown.
Introduction to Alcohols, Phenols and Ethers
- Definition: Alcohols: R-OH aliphatic; Phenols: Ar-OH; Ethers: R-O-R.
- Importance: Basic for detergents, antiseptics, fragrances.
- Applications: Ethanol in polishing, sugar/cotton/paper with -OH.
- Expanded: Evidence: Substitution effects; debates: Ether as alkoxy; real: Life without paper.
7.1 Classification
- Alcohols: Mono/di/tri/polyhydric; primary/secondary/tertiary; allylic/benzylic/vinylic.
- Phenols: Mono/di/trihydric.
- Ethers: Simple/mixed.
- Expanded: Evidence: Structures; debates: Hybridisation; real: Examples like ethylene glycol.
Conceptual Diagram: Classification
Tree: Hydric types, carbon attachment; arrows to examples.
7.2 Nomenclature
- Alcohols: Alkane -e + ol; positions numbered.
- Phenols: Phenol; ortho/meta/para for substitutes.
- Ethers: Alkoxyalkane; larger parent.
- Expanded: Evidence: Table 7.1/7.2; debates: Common vs IUPAC; real: Anisole methoxybenzene.
Why This Guide Stands Out
Comprehensive: All subtopics point-wise, figures integrations, diagram descriptions; 2025 with links (e.g., preparations), mechanisms analyzed for depth.
Table 7.1: Names of Alcohols
- Key Values: Methanol CH3OH, etc.
- Trends: Position indicators.
- Applications: Systematic naming.
- Expanded: Evidence: Data; debates: Polyols; real: Glycerol.
7.3 Structures of Functional Groups
- Physical: Bond angles, lengths; phenol partial double.
- Expanded: Evidence: Fig 7.1; debates: Repulsion; real: Ether angle larger.
Exam Case Studies
Naming compounds; acid hydration; phenol acidity.
Key Themes & Tips
- Aspects: Preparations, reactions, properties.
- Tip: Memorize mechanisms; distinguish tests; differentiate alcohols/phenols.
Project & Group Ideas
- Model ethanol structure.
- Debate: Alcohol uses pros/cons.
- Analyze ether synthesis.
Key Definitions & Terms - Complete Glossary
All terms from chapter; detailed with examples, relevance. Expanded: 30+ terms grouped by subtopic; added advanced like "Markovnikov rule", "Williamson synthesis".
Alcohol
R-OH aliphatic. Ex: Ethanol. Relevance: Hydration.
Phenol
Ar-OH. Ex: C6H5OH. Relevance: Acidity.
Ether
R-O-R. Ex: Diethyl ether. Relevance: Symmetrical/mixed.
Primary Alcohol
-CH2OH. Ex: Methanol. Relevance: Oxidation to acid.
Secondary Alcohol
>CHOH. Ex: Isopropanol. Relevance: Ketone oxidation.
Tertiary Alcohol
>C(OH)R. Ex: tert-Butanol. Relevance: No oxidation.
Allylic Alcohol
Next to C=C. Ex: Allyl alcohol. Relevance: Reactivity.
Benzylic Alcohol
Next to aromatic. Ex: Benzyl alcohol. Relevance: Oxidation.
Vinylic Alcohol
On C=C. Ex: Vinyl alcohol. Relevance: Unstable.
Markovnikov Rule
H to less H carbon. Ex: Propene hydration. Relevance: Regioselectivity.
Hydroboration-Oxidation
Anti-Markovnikov. Ex: Alkene to alcohol. Relevance: Syn addition.
Grignard Reagent
RMgX. Ex: With carbonyl. Relevance: C-C bond.
Tip: Group by type (compounds/reactions/properties); examples for recall. Depth: Debates (e.g., phenol vs alcohol). Errors: Confuse primary/secondary. Interlinks: To haloalkanes (Ch6). Advanced: Mechanisms. Real-Life: Ethanol fuel. Graphs: Bond lengths. Coherent: Evidence → Interpretation. For easy learning: Flashcard per term with example.
60+ Questions & Answers - NCERT Based (Class 12) - From Exercises & Variations
Based on chapter + expansions. Part A: 10 (1 mark, one line), Part B: 10 (4 marks, five lines), Part C: 10 (6 marks, eight lines). Answers point-wise in black text.
Part A: 1 Mark Questions (10 Qs - Short)
1. Define alcohol.
R-OH aliphatic.
2. What is phenol?
Ar-OH aromatic.
3. Ether general?
R-O-R.
4. Primary alcohol?
-CH2OH attached.
5. Markovnikov rule?
H to less H C.
6. Common oxidation?
Primary to acid.
7. Phenol acidity?
Resonance stable ion.
8. Ether prep?
Williamson synthesis.
9. Bond angle alcohol?
~109° less tetrahedral.
10. Vinylic alcohol?
On C=C bond.
Part B: 4 Marks Questions (10 Qs - Medium, Exactly 5 Lines Each)
1. Classify alcohols.
- Mono/di/tri/polyhydric.
- Primary/secondary/tertiary.
- Allylic/benzylic.
- Vinylic sp2.
- Ex: Ethanol primary.
2. Nomenclature alcohols.
- Alkane -e + ol.
- Number from OH end.
- Poly: Di/tri ol.
- Ex: Propan-2-ol.
- Table 7.1.
3. Structures functional.
- Alcohol sp3 109°.
- Phenol sp2 136 pm.
- Ether >109° bulky.
- Fig 7.1.
- Resonance phenol.
4. Acid hydration.
- Alkene + H2O/H+.
- Markovnikov rule.
- Carbocation mech.
- Ex: Propene isopropanol.
- Steps: Protonate, nucleophile, deprotonate.
5. Hydroboration.
- BH3 then H2O2/NaOH.
- Anti-Markovnikov.
- B to less H C.
- Ex: Propene propanol-1.
- Syn addition.
6. Grignard alcohols.
- RMgX + carbonyl.
- HCHO primary.
- Aldehyde secondary.
- Ketone tertiary.
- Hydrolysis adduct.
7. Phenol prep haloarene.
- ArCl + NaOH high T/P.
- Dow process.
- From diazonium.
- Cumene hydroperoxide.
- Ex: Chlorobenzene phenol.
8. Ether Williamson.
- RO- + R'X.
- SN2 alkyl halide.
- Mixed ethers.
- Ex: Ethoxide + methyl iodide.
- Avoid tertiary X.
9. Phenol acidity why.
- Resonance phenoxide.
- Delocalized charge.
- Alcohol no resonance.
- pKa phenol 10.
- Ex: Reacts NaOH.
10. Distinguish alcohol phenol.
- FeCl3 color phenol.
- Acidity NaOH phenol.
- Oxidation alcohols vary.
- Iodoform secondary alcohol.
- Boiling points.
Part C: 6 Marks Questions (10 Qs - Long, Exactly 8 Lines Each)
1. Discuss classification.
- Alcohols: Hydric mono/di.
- 1°/2°/3° based C.
- Allylic next C=C.
- Benzylic next ring.
- Vinylic on C=C.
- Phenols: Mono/di/tri.
- Ethers: Simple/mixed.
- Ex: Glycerol tri.
2. Nomenclature details.
- Alcohols: Chain number OH.
- Poly retain e + diol.
- Phenols: Phenol base.
- o/m/p substitutes.
- Ethers: Alkoxy smaller.
- Parent larger alkane.
- Table 7.2 examples.
- Common: Alkyl ether.
3. Structures bonds.
- Alcohol: sp3 C-O 143 pm.
- Angle 108.9° repulsion.
- Phenol: sp2 C-O 136 pm.
- Resonance double char.
- Ether: sp3 O angle 111.7°.
- C-O 141 pm.
- Fig 7.1 methanol/phenol/methoxymethane.
- Bulky groups wider angle.
4. Preparations alcohols alkenes.
- Acid hydration H+.
- Markovnikov carbocation.
- Hydroboration BH3/H2O2.
- Anti-Markovnikov syn.
- Steps: Protonate, water attack.
- Ex: Ethene ethanol.
- Unsymmetrical differ products.
- Mechanism three steps.
5. From carbonyls.
- Reduce aldehyde/ketone.
- H2/Pd or NaBH4/LiAlH4.
- Aldehyde primary.
- Ketone secondary.
- Acid/ester LiAlH4 primary.
- Ex: Acetic acid ethanol.
- Catalytic hydrogenation esters.
- LiAlH4 strong expensive.
6. Grignard reactions.
- RMgX + HCHO primary.
- With RCHO secondary.
- With RCOR tertiary.
- Nucleophilic addition.
- Hydrolysis H3O+.
- Ex: CH3MgBr + acetone tert-butanol.
- Adduct Mg(OR)X.
- No with tertiary carbonyl.
7. Phenol preparations.
- Haloarene NaOH 623K.
- Sulphonic acid fusion.
- Diazonium H2O boil.
- Cumene peroxide.
- Ex: Chlorobenzene phenol.
- Industrial cumene.
- Lab diazonium.
- Mechanisms SNAr halo.
8. Ether preparations.
- Dehydration alcohol H2SO4.
- Williamson RO- + RX.
- Simple 140°C alcohol.
- Mixed primary X.
- Ex: Ethanol diethyl ether.
- SN2 mechanism.
- Avoid elimination tertiary.
- Phenol ArONa + RX.
9. Properties physical.
- Boiling H-bond alcohols > ethers.
- Solubility water H-bond.
- Phenol higher boil resonance.
- Lower members soluble.
- Ex: Ethanol miscible water.
- Ethers inert less polar.
- Viscosity increase chain.
- Density less water.
10. Reactions alcohols.
- Acidity Na alkoxide.
- Esterification acid.
- Dehydration alkene.
- Oxidation PCC/KMnO4.
- 1° aldehyde/acid.
- 2° ketone.
- 3° no.
- Ex: Lucas test distinguish.
Tip: Diagrams for mechanisms; practice naming. Additional 30 Qs: Variations on reactions, preparations.
Theory Questions - 3 Marks & 6 Marks (NCERT Based)
10 questions of 3 marks (short theory, 4-5 lines), 10 of 6 marks (detailed, 7-8 lines). Answers in black text.
3 Marks Questions (10 Qs)
1. Define phenol.
- Ar-OH benzene.
- Resonance double.
- Acidic nature.
- Ex: C6H5OH.
2. Ether classification.
- Simple same R.
- Mixed different.
- Ex: Diethyl simple.
- Anisole mixed.
3. Nomenclature phenols.
- Phenol base.
- o/m/p methylphenol.
- Benzenediol 1,2 etc.
- Ex: Catechol 1,2.
4. Bond angle why less?
- Alcohol repulsion lone pairs.
- 109°-28'.
- Phenol sp2.
- Ether >109° bulky.
5. Acid hydration mechanism.
- Protonate alkene.
- Carbocation water.
- Deprotonate alcohol.
- Markovnikov.
6. Hydroboration why anti.
- B to less H C.
- Less steric.
- Oxidation alcohol.
- Ex: Primary yield.
7. Grignard types.
- HCHO 1°.
- RCHO 2°.
- RCOR 3°.
- Hydrolysis.
8. Phenol from cumene.
- Cumene peroxide air.
- H+ cleavage.
- Phenol + acetone.
- Industrial.
9. Ether dehydration.
- Alcohol H2SO4 140°.
- Simple ethers.
- Ex: Ethanol diethyl.
- Carbocation mech.
10. Phenol acidity explain.
- Phenoxide resonance.
- Charge delocalized.
- Stable ion.
- Alcohol no.
6 Marks Questions (10 Qs)
1. Distinguish alcohol/phenol/ether.
- Alcohol R-OH aliphatic.
- Phenol Ar-OH acidic.
- Ether R-O-R inert.
- Alcohol H-bond boil high.
- Phenol resonance short bond.
- Ether angle large.
- Ex: Ethanol/phenol/diethyl.
2. Classification alcohols phenols.
- Alcohols hydric mono/poly.
- 1°/2°/3° C attachment.
- Allylic/benzylic special.
- Phenols mono/di/tri.
- Ex: Ethylene glycol di.
- Structures shown.
- Vinylic separate.
3. Nomenclature ethers.
- Common alkyl ether alphabetical.
- IUPAC alkoxyalkane larger parent.
- Simple di alkyl.
- Ex: Ethyl methyl ether methoxyethane.
- Table 7.2.
- Phenyl anisole methoxybenzene.
- Complex numbers.
4. Structures compare.
- Alcohol C-O sigma sp3.
- Bond 143 pm angle 108.9°.
- Phenol partial double 136 pm.
- Conjugation ring.
- Ether tetrahedral 141 pm >109°.
- Repulsion bulky R.
- Fig 7.1 examples.
5. Preparations alcohols carbonyl.
- Reduce H2/catalyst.
- NaBH4 aldehyde primary.
- LiAlH4 ketone secondary.
- Acid LiAlH4 primary.
- Ester H2 catalyst.
- Ex: Acetaldehyde ethanol.
- LiAlH4 expensive special.
6. Phenol from diazonium.
- ArNH2 diazotize NaNO2/HCl.
- ArN2+ boil H2O.
- Phenol + N2.
- Lab method.
- Ex: Aniline phenol.
- Mechanism hydrolysis.
- Avoid explosion cold.
7. Williamson synthesis.
- NaOR + R'X ether.
- SN2 primary X best.
- Mixed ethers.
- Aryl halide no SN2.
- Ex: Sodium ethoxide + methyl iodide methoxyethane.
- Heat reflux.
- Avoid beta elimination.
8. Physical properties compare.
- Alcohols H-bond high boil.
- Phenols higher resonance.
- Ethers no H-bond low boil.
- Solubility alcohols/phenols water.
- Ethers less.
- Ex: Ethanol 78°C boil.
- Increase chain decrease solubility.
9. Chemical reactions alcohols.
- Na metal alkoxide + H2.
- Acid ester + water.
- PX3/PCl5 alkyl halide.
- Dehydrate H2SO4 alkene.
- Oxidize vary 1°/2°/3°.
- Ex: Ethanol acetic acid.
- Mechanism carbocation dehydrate.
10. Phenol reactions.
- Acidity Na phenoxide.
- Electrophilic ring nitration.
- Kolbe CO2 salicylic.
- Reimer-Tiemann CHCl3 aldehyde.
- Ether with RX.
- Ex: Bromination tribromo.
- Activating ortho/para.
Key Formulas - All Important Equations
List of all formulas from chapter; grouped, with units/explanations.
| Formula | Description | Units/Example |
|---|---|---|
| R-OH | Alcohol general | Ethanol C2H5OH |
| Ar-OH | Phenol | C6H5OH |
| R-O-R | Ether | (C2H5)2O |
| C=C + H2O/H+ | Hydration | Propene propan-2-ol |
| C=C + BH3/H2O2 | Hydroboration | Propene propan-1-ol |
| RMgX + R'COR | Grignard | Tertiary alcohol |
| ROH + Na | Alkoxide | RONa + 1/2 H2 |
| ROH + H2SO4 140° | Dehydration ether | Ethanol diethyl |
Tip: Memorize with reactions; practice mechanisms.
Derivations - Detailed Guide
Key derivations with steps; from PDF (e.g., mechanisms hydration, Williamson).
Acid Catalysed Hydration
- Step 1: Protonate alkene H3O+.
- Step 2: Carbocation form.
- Step 3: Water nucleophile.
- Step 4: Deprotonate alcohol.
Depth: Markovnikov stable carbocation.
Hydroboration-Oxidation
- Step 1: BH3 add anti-Markovnikov.
- Step 2: Trialkylborane.
- Step 3: H2O2/NaOH oxidize.
- Step 4: Alcohol syn.
Depth: Boron less substituted.
Williamson Synthesis
- Step 1: Alkoxide form RONa.
- Step 2: SN2 with RX.
- Step 3: Ether ROR'.
- Step 4: NaX byproduct.
Depth: Primary halide best.
Tip: Step proofs; examples apply. Depth: Assumptions (carbocation stability).
Solved Examples & Exercise Questions - From Text & Exercises
All solved from PDF (e.g., 7.1, 7.2); exercise Qs similar solved.
Example 7.1: Naming Compounds
Simple Explanation: IUPAC rules.
- Step 1: Longest chain.
- Step 2: Number OH low.
- Step 3: Substituents prefix.
- Step 4: Suffix ol.
- Simple Way: Check positions.
Example 7.2: Products from Reactions
Simple Explanation: Reduction/hydration/Grignard.
- Step 1: Butanal reduce butan-1-ol.
- Step 2: Propene hydration propan-2-ol.
- Step 3: Propanone + CH3MgBr 2-methylpropan-2-ol.
- Step 4: Hydrolysis.
- Simple Way: Identify type.
Exercise Questions Solved (Sample)
Intext 7.1: Classify Alcohols
Solution: (i) 1° (ii) 2° (iii) 1° (iv) 2° (v) 1° (vi) 3°.
Intext 7.2: Allylic Alcohols
Solution: (ii), (iv), (vi).
Tip: All chapter examples/exercises covered; numerical steps where applicable.
Lab Activities - Step-by-Step Guide
From PDF (implied like Lucas test, iodoform); explain how to do.
Activity 1: Lucas Test for Alcohols
Step-by-Step:
- Step 1: Add ZnCl2/HCl to alcohol.
- Step 2: Observe turbidity time.
- Step 3: 3° immediate, 2° 5 min, 1° no.
- Observation: Cloudiness.
- Precaution: Concentrated HCl carefully.
Activity 2: Iodoform Test
Step-by-Step:
- Step 1: Add I2/NaOH to compound.
- Step 2: Yellow ppt CHI3.
- Step 3: For CH3CH(OH)- or CH3CO-.
- Observation: Iodoform smell.
- Precaution: Heat gently.
Note: PDF mentions reactions; general activities for distinctions.
Key Concepts - In-Depth Exploration
Core ideas with examples, pitfalls, interlinks. Expanded: All concepts with steps/examples/pitfalls.
Markovnikov Rule
Steps: 1. H+ to alkene, 2. Stable carbocation, 3. Nucleophile add. Ex: Propene. Pitfall: Ignore rearrangement. Interlink: Hydration. Depth: Electrophilic addition.
Phenol Acidity
Steps: 1. Lose H+, 2. Resonance stabilize, 3. Delocalize charge. Ex: Phenoxide. Pitfall: Compare to alcohol. Interlink: Electrophilic sub. Depth: pKa values.
Williamson Synthesis
Steps: 1. Alkoxide nucleophile, 2. SN2 on halide, 3. Ether form. Ex: Methoxyethane. Pitfall: Tertiary halide elimination. Interlink: Haloalkanes. Depth: Inversion.
Advanced: Reimer-Tiemann. Pitfalls: Naming errors. Interlinks: Organic reactions. Real: Industrial ethanol. Depth: 12 concepts. Examples: Reactions. Graphs: Boiling trends. Errors: Mechanism mistakes. Tips: Draw structures.
Interactive Quiz - Master Alcohols, Phenols and Ethers
10 MCQs; 80%+ goal. Covers nomenclature, preparations, reactions.
Quick Revision Notes & Mnemonics
Concise for all subtopics; mnemonics.
Classification
- 1°/2°/3°: Primary School Teacher (PST).
Preparations
- Hydration, Hydroboration, Grignard (HHG).
Reactions
- Oxidation: Primary Acid, Secondary Ketone, Tertiary None (PAST None).
Overall Mnemonic: "Classify Name Prepare React" (CNPR). Flashcards: One per. Easy: Bullets, bold.
Key Terms & Formulas - All Key
Expanded table 30+ rows; quick ref.
| Term/Formula | Description | Example | Usage |
|---|---|---|---|
| Alcohol | R-OH | Ethanol | Hydration |
| Phenol | Ar-OH | C6H5OH | Acidic |
| Ether | R-O-R | (C2H5)2O | Inert |
| Markovnikov | H less H | Propene 2-ol | Regio |
| Hydroboration | Anti-Mark | Propene 1-ol | Syn |
| Grignard | RMgX | With ketone 3° | C-C |
| Williamson | RO- + RX | Mixed ether | SN2 |
| Lucas Test | ZnCl2/HCl | 3° turbid fast | Distinguish |
| Iodoform | I2/NaOH | CH3CHOH- yellow | Methyl ketone |
| Reimer-Tiemann | CHCl3/NaOH | Phenol salicylaldehyde | Aldehyde intro |
Tip: Sort subtopic. Easy: Scan.
Key Processes & Diagrams - Step-by-Step
Expanded major; desc diags.
Process 1: Dehydration of Alcohol to Ether
Step-by-Step:
- Step 1: Protonate OH H2SO4.
- Step 2: Water leave carbocation.
- Step 3: Another ROH nucleophile.
- Step 4: Deprotonate ether.
- Step 5: 140°C for ether.
- Diagram Desc: Arrows protonation, loss H2O.
Process 2: Oxidation of Alcohols
Step-by-Step:
- Step 1: Primary PCC aldehyde.
- Step 2: KMnO4 acid.
- Step 3: Secondary ketone.
- Step 4: Tertiary no reaction.
- Step 5: Chromic acid used.
- Diagram Desc: Structures before/after oxidation.
Tip: Label diags; analogies (oxidation as loss H).
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