Class 12 Chemistry · Chapter 7
Short answer:
Is chapter me NCERT ke exercise me tot 20 questions hain — nomenclature, preparation methods (alcohols, phenols, ethers), physical properties (H-bonding ki wajah se high boiling point aur water-solubility), alcohols ki chemical reactions (esterification, oxidation, dehydration), phenol ki acidity (comparison alcohol aur substituted phenols se), phenol ki electrophilic substitution reactions (halogenation, nitration, Kolbe's reaction, Reimer-Tiemann reaction), aur ethers ki preparation (Williamson synthesis) + reactions cover hoti hain. Board me distinguishing tests (Lucas test, ferric chloride test) aur acidity/reactivity order wale questions bahut common hain.
Alcohols, phenols aur ethers teeno me ek hi functional link hai — oxygen ek single bond se attached hota hai — lekin unka behaviour bilkul alag hota hai kyunki oxygen kis group se juda hai ye sabse zyada matter karta hai. Alcohol me -OH ek sp3 carbon se juda hota hai, phenol me -OH seedha benzene ring (sp2 carbon) se juda hota hai, aur ether me oxygen do carbon groups ke beech bridge banata hai (-O- koi replaceable H nahi rakhta). Yehi structural farak decide karta hai ki phenol acidic kyun hai jabki alcohol nahi, aur ether kyun sabse zyada unreactive hai teeno me se.
Chapter 7 Summary — 5 Minute Revision
1. Classification aur Nomenclature
Alcohols classify hote hain kis carbon pe -OH hai uske hisaab se:
- 1° (primary) alcohol: -OH us carbon pe jo sirf ek aur carbon se juda hai. Example: CH3CH2OH (ethanol)
- 2° (secondary) alcohol: -OH us carbon pe jo do carbons se juda hai. Example: (CH3)2CHOH (isopropyl alcohol)
- 3° (tertiary) alcohol: -OH us carbon pe jo teen carbons se juda hai. Example: (CH3)3COH (tert-butyl alcohol)
IUPAC naming: parent chain me -OH wale carbon ko lowest number milta hai, suffix "-ol" lagta hai. Example: CH3CH(OH)CH2CH3 = butan-2-ol. Phenol khud IUPAC-accepted trivial name hai (benzenol nahi likhte). Ethers ko substitutive naming me "alkoxyalkane" bolte hain — CH3-O-C2H5 = methoxyethane.
2. Preparation ke Methods
Alcohols
- Alkenes se acid-catalysed hydration (Markovnikov addition) — H2SO4 + H2O
- Grignard reagent + carbonyl compound (aldehyde/ketone/ester) phir hydrolysis
- Carbonyl compounds (aldehyde/ketone) ki reduction — NaBH4 ya LiAlH4 se
- Alkyl halides ka hydrolysis — aqueous NaOH/KOH ke saath (SN2/SN1 mechanism)
Phenols
- Cumene process (industrial, sabse important) — cumene ko air-oxidise karke cumene hydroperoxide banta hai, phir dilute acid se treat karke phenol + acetone milta hai
- Benzene diazonium salt ka hydrolysis — garam pani ke saath
- Haloarenes ka fusion NaOH ke saath high temperature/pressure pe (Dow process)
Ethers
- Williamson synthesis — sodium alkoxide + alkyl halide (SN2 mechanism, sabse reliable method)
- Alcohols ka intermolecular dehydration — excess alcohol + conc. H2SO4, 413K
3. Physical Properties — H-bonding ka role
Alcohols aur phenols me -OH group intermolecular hydrogen bonding banata hai — isi wajah se inka boiling point similar molecular mass ke alkanes/haloalkanes se kaafi zyada hota hai. Ether me H-bonding donor nahi hoti (koi H directly O se juda hokar dusre molecule ke O se bond nahi banata as donor) isliye ether ka boiling point corresponding alcohol se kam hota hai, lekin alkane se zyada (kyunki O thoda dipole-dipole interaction deta hai). Solubility: chhote alcohols/phenols paani ke saath H-bond bana sakte hain isliye paani me ghulnashil hote hain — chain lambi hone pe hydrophobic part dominate karta hai aur solubility ghatti hai.
4. Alcohols ki Chemical Reactions
- Esterification: Alcohol + carboxylic acid (conc. H2SO4 catalyst) → ester + water. Reversible reaction hai.
- Oxidation: 1° alcohol → aldehyde (mild oxidant jaise PCC) → aage oxidise hoke carboxylic acid (strong oxidant KMnO4/K2Cr2O7). 2° alcohol → ketone. 3° alcohol normal conditions me oxidise nahi hota kyunki uske pass alpha-H hi nahi hai jisse C=O bane.
- Dehydration: Alcohol + conc. H2SO4 garam karne pe alkene banta hai (E1 mechanism, Zaitsev's rule follow hoti hai — zyada substituted alkene major product). Ease of dehydration: 3° > 2° > 1° (carbocation stability ke hisaab se).
- Reaction with HX (Lucas reagent): conc. HCl + anhydrous ZnCl2 se alkyl halide banta hai — turbidity appear hone ki speed alcohol ka class batati hai.
5. Acidity of Phenols — Alcohol se comparison
Phenol acidic isliye hota hai kyunki phenoxide ion (phenol ke H+ lose karne ke baad banne wala anion) resonance se stabilise ho jaata hai — negative charge oxygen ke saath-saath ortho aur para positions pe bhi delocalise ho sakta hai. Alcohol me ye resonance possible nahi hai kyunki alkoxide ion (RO-) ke paas koi pi-system nahi hai jisme charge delocalise ho — isliye alkoxide sirf inductive effect se hi stabilise hota hai, jo resonance jitna effective nahi. Yehi wajah hai ki phenol (pKa ~10) alcohol (pKa ~16) se lakhon guna zyada acidic hai, aur paani (pKa ~15.7) se bhi zyada acidic hai.
Substituent effect on phenol acidity: Electron-withdrawing groups (jaise -NO2, -Cl, -CHO) phenoxide ion ko aur stabilise karte hain (negative charge ko spread karte hain) — isliye acidity BADHATI hai, aur ye effect ortho/para position pe zyada hota hai (direct conjugation ki wajah se). Electron-donating groups (jaise -CH3, -OCH3, -NH2) phenoxide ko destabilise karte hain (electron density push karte hain jo negative charge accumulation ko favour nahi karta) — isliye acidity GHATTI hai.
6. Reactions of Phenols
- Electrophilic substitution: -OH group ring ko activate karta hai (ortho/para directing) kyunki oxygen ka lone pair ring ke saath resonance karta hai aur electron density badhata hai — isliye phenol benzene se zyada easily electrophilic substitution karta hai (halogenation without catalyst bhi ho jata hai).
- Kolbe's reaction: Sodium phenoxide + CO2, phir acidification — ortho-hydroxybenzoic acid (salicylic acid) banta hai. Reagents: NaOH (phenoxide banane ke liye) + CO2 under pressure/heat.
- Reimer-Tiemann reaction: Phenol + CHCl3 + NaOH (aqueous), garam karne pe — ortho position pe -CHO group introduce hoti hai, hydrolysis ke baad salicylaldehyde banta hai. Mechanism dichlorocarbene (:CCl2) intermediate se hoke jata hai.
- Ferric chloride test: Phenol neutral FeCl3 ke saath violet/purple colouration deta hai — ye phenolic -OH ki characteristic identification test hai, alcohol ye test nahi deta.
7. Preparation aur Reactions of Ethers
Williamson synthesis SN2 mechanism follow karta hai — isliye better sterically alkyl halide primary hona chahiye (bulky/3° halide use karne pe elimination dominate karega, ether kam banega). Ethers relatively unreactive hote hain but strong acids (conc. HI/HBr) ke saath heat karne pe C-O bond cleave hota hai aur alkyl halide + alcohol/phenol banta hai.
Poore Class 12 Chemistry ke handwritten colour notes
IITian & district toppers ke banaye short notes — revision-ready, diagram ke saath. Board se pehle poora syllabus 3 din me revise.
Exercise Questions — Solutions (Q1–Q20)
Q1. IUPAC naming likho in structures ki: (i) CH3CH(OH)CH2CH2CH3 (ii) (CH3)3C-OH
(i) Pentan-2-ol — OH wale carbon ko lowest locant 2 milta hai.
(ii) 2-Methylpropan-2-ol — tertiary alcohol, longest chain propane hai, OH aur methyl dono carbon 2 pe hain.
CH3-CH(OH)-CH2-CH2-CH3 → pentan-2-ol
Q2. Ek 1°, 2° aur 3° alcohol ko Lucas test se kaise distinguish karoge?
Lucas reagent (conc. HCl + anhydrous ZnCl2) alcohol ko alkyl chloride me convert karta hai, jo turbid/milky ho jata hai (immiscible in water). Reaction rate carbocation stability pe depend karti hai:
- 3° alcohol — turbidity turant (within minutes, room temperature pe)
- 2° alcohol — turbidity 5-10 minute me (warming zaroori ho sakti hai)
- 1° alcohol — turbidity room temp pe nahi aati, sirf heating ke baad
Isliye Lucas test se teeno ko time ke basis pe distinguish karte hain.
Q3. Phenol, ethanol se zyada acidic kyun hai? Reason samjhao.
Phenol jab H+ lose karta hai to phenoxide ion banta hai, jiska negative charge resonance ke through oxygen ke saath-saath ring ke ortho aur para carbons pe bhi delocalise ho jaata hai — ye extra stabilisation deta hai. Ethanol jab H+ lose karta hai to ethoxide ion (C2H5O-) banta hai, jisme koi pi-system nahi hai resonance ke liye — sirf weak inductive effect se stabilise hota hai. Isliye phenoxide zyada stable hai ethoxide se, aur phenol zyada easily H+ deta hai — matlab zyada acidic hai.
C6H5-OH ⇌ C6H5-O(-) + H(+) [resonance-stabilised]
Q4. Substituted phenols me acidity ka order likho aur reason do: phenol, p-nitrophenol, p-cresol (p-methylphenol).
Acidity order: p-nitrophenol > phenol > p-cresol
-NO2 ek electron-withdrawing group hai jo resonance aur inductive dono se phenoxide ion ke negative charge ko stabilise karta hai — isliye p-nitrophenol sabse zyada acidic. -CH3 electron-donating group hai jo electron density ring me push karta hai — ye phenoxide ki stability GHATTA deta hai (negative charge accumulate karna favour nahi karta) — isliye p-cresol sabse kam acidic.
Q5. Ethanol ko conc. H2SO4 ke saath alag-alag conditions me garam karne pe kya products bante hain?
Condition pe depend karta hai:
- 413 K, excess ethanol (140°C): intermolecular dehydration — diethyl ether banta hai (Williamson-type condensation)
- 443 K (170°C), excess acid: intramolecular dehydration — ethene banta hai (E1 elimination)
C2H5OH + C2H5OH --413K, H2SO4--> C2H5-O-C2H5 + H2O
C2H5OH --443K, H2SO4--> CH2=CH2 + H2O
Q6. Kolbe's reaction likho — reagents, conditions aur product samjhao.
Sodium phenoxide ko CO2 ke saath 400 K temperature aur 4-7 atm pressure pe treat karte hain, phir product ko dilute acid se acidify karte hain. Electrophile CO2 phenoxide ring ke ortho position pe attack karta hai (ortho-directing effect of O-) aur salicylic acid (ortho-hydroxybenzoic acid) banta hai.
C6H5-O(-)Na(+) + CO2 --400K,4-7atm--> sodium salicylate --H3O+--> salicylic acid (o-HO-C6H4-COOH)
Q7. Reimer-Tiemann reaction likho.
Phenol ko CHCl3 aur aqueous NaOH ke saath garam karte hain. Base CHCl3 se HCl remove karke dichlorocarbene (:CCl2) generate karta hai, jo electrophile ki tarah phenoxide ring ke ortho position pe attack karta hai. Intermediate ka hydrolysis karne pe salicylaldehyde (o-hydroxybenzaldehyde) banta hai.
C6H5OH + CHCl3 + NaOH --heat--> o-HO-C6H4-CHO (salicylaldehyde) + NaCl + H2O
Q8. Williamson ether synthesis se unsymmetrical ether banate waqt kya precaution rakhna chahiye?
Williamson synthesis SN2 mechanism se hoti hai — sodium alkoxide nucleophile hai jo alkyl halide pe backside attack karta hai. Isliye alkyl halide hamesha 1° (primary) lena chahiye, chahe alkoxide 1°/2°/3° ho. Agar bulky (2°/3°) alkyl halide use karenge to nucleophile base ki tarah act karke elimination (alkene) de dega, ether nahi banega — isliye sirf primary halide + koi bhi alkoxide, ye combination sahi hai. Ulta karna (primary alkoxide + tertiary halide) common galti hai jo galat/kam yield deti hai.
CH3O(-)Na(+) + C2H5-Br --SN2--> CH3-O-C2H5 + NaBr
Q9. Alcohols aur phenols ka boiling point corresponding haloalkanes se zyada kyun hota hai?
Alcohol/phenol ke -OH group me H directly electronegative O se juda hota hai, jo intermolecular hydrogen bonding banata hai — molecules ek dusre se extra force se bandhe rehte hain, isliye vaporise karne ke liye zyada energy chahiye. Haloalkanes me aisi hydrogen bonding nahi hoti (halogen H-bond donor nahi hai us tarah), sirf dipole-dipole aur van der Waals forces hoti hain, jo weaker hain. Isliye alcohols/phenols ka boiling point zyada hota hai.
Q10. Ether ka boiling point corresponding alcohol se kam kyun hota hai?
Ether molecule me oxygen hai lekin uske sath koi H directly nahi juda (donor H nahi hai) — isliye ether molecules ek dusre ke saath intermolecular hydrogen bonding nahi bana sakte. Sirf weak dipole-dipole interactions hoti hain. Alcohol me -OH ka H hydrogen bonding banata hai jo extra intermolecular force deta hai. Isliye same molecular formula/mass ke liye alcohol ka boiling point ether se zyada hota hai.
Q11. Phenol benzene se zyada easily electrophilic substitution kyun karta hai?
-OH group ka oxygen apna lone pair benzene ring ke pi-system ke saath resonance me bhej deta hai — isse ring me electron density badh jaati hai, especially ortho aur para positions pe. Zyada electron density electrophile ko attract karti hai aur transition state stabilise karti hai — isliye phenol benzene se zyada reactive hota hai electrophilic substitution ke liye, aur -OH ortho/para directing group hai.
Q12. 3° alcohol ko oxidise karne pe carboxylic acid kyun nahi banta?
Oxidation me alpha-carbon (jisme -OH hai) pe present H remove hokar C=O double bond banta hai. 1°/2° alcohol ke alpha-carbon pe H hota hai (1° me 2 H, 2° me 1 H) isliye ye aldehyde/ketone me oxidise ho sakte hain, aage aldehyde carboxylic acid me. Lekin 3° alcohol ke alpha-carbon (jisme -OH hai) pe koi H nahi hota (teeno bonds carbon se hi bane hain) — isliye normal oxidising conditions me 3° alcohol oxidise nahi hota. Strong/harsh conditions me C-C bond breakage se chhote products ban sakte hain, but ye simple oxidation nahi hai.
Q13. Cumene process se phenol kaise banaya jaata hai? (Industrial method)
Benzene ko propene ke saath Friedel-Crafts alkylation se cumene (isopropylbenzene) banaya jaata hai. Cumene ko air se oxidise karke cumene hydroperoxide banta hai. Ise dilute acid se treat karne pe phenol aur acetone dono milte hain (by-product acetone commercially useful hai).
Benzene + CH2=CH-CH3 --AlCl3--> Cumene --O2--> Cumene hydroperoxide --dil. H2SO4--> Phenol + Acetone
Q14. Ferric chloride test kya batata hai aur alcohol se phenol ko kaise distinguish karta hai?
Phenol neutral aqueous FeCl3 solution ke saath violet/purple colouration deta hai kyunki phenol FeCl3 ke saath coloured complex banata hai. Simple alcohols ye colouration nahi dete kyunki unme phenolic -OH nahi hota. Isliye ye test phenolic compounds ko alcoholic compounds se distinguish karne ke liye use hota hai.
Q15. Grignard reagent se alcohol kaise banate hain? Ek example do jisme 3° alcohol bane.
Grignard reagent (RMgX) ketone ke saath react karke, hydrolysis ke baad 3° alcohol deta hai (agar dono R groups alkyl hain).
CH3MgBr + (CH3)2C=O --dry ether--> intermediate --H3O+--> (CH3)3C-OH (tert-butyl alcohol)
Q16. Diethyl ether ko conc. HI ke saath garam karne pe kya hota hai?
Ether ka C-O bond strong acid (HI) ke saath cleave ho jaata hai — pehle ek alkyl group alkyl iodide banta hai aur alcohol bachta hai, excess HI ke saath alcohol bhi aage alkyl iodide me convert ho jaata hai.
C2H5-O-C2H5 + HI --heat--> C2H5OH + C2H5I (excess HI se C2H5OH bhi → C2H5I + H2O)
Q17. Anisole (methoxybenzene) me electrophilic substitution kaha hoti hai aur kyun?
Anisole me -OCH3 group bhi phenol ke -OH ki tarah oxygen ka lone pair ring ke saath resonance karta hai — electron density ortho aur para positions pe badhati hai. Isliye anisole me electrophilic substitution (nitration, halogenation, sulphonation) ortho/para positions pe hoti hai, aur ring benzene se zyada reactive hoti hai.
Q18. Alcohol aur phenol dono me -OH hai — phir bhi phenol ko sodium hydroxide se neutralise kiya ja sakta hai lekin alcohol nahi. Kyun?
Phenol (pKa ~10) NaOH (strong base) se react karke sodium phenoxide + water bana leta hai kyunki phenol paani se zyada acidic hai. Alcohol (pKa ~16) paani se bhi kam acidic hota hai, isliye NaOH usse deprotonate nahi kar paata — equilibrium bahut heavily reactants ki taraf hota hai, practically koi reaction nahi hoti.
Q19. Esterification reaction likho aur bolo ye reversible kyun hai.
Alcohol carboxylic acid ke saath conc. H2SO4 (catalyst/dehydrating agent) ki presence me react karke ester aur paani banata hai. Ye reversible hai kyunki ester ko paani ke saath (acid/base catalysis) wapas hydrolyse karke original acid aur alcohol wapas mil sakte hain — forward (esterification) aur backward (hydrolysis) dono possible hain, isliye equilibrium set hota hai.
CH3COOH + C2H5OH ⇌(conc. H2SO4) CH3COOC2H5 + H2O
Q20. Propan-1-ol aur propan-2-ol ko distinguish karne ka simple chemical test batao.
Lucas test use kar sakte hain — propan-2-ol (2°) turbidity kuch minute me degi, propan-1-ol (1°) sirf heating ke baad. Iodoform test bhi kaam aata hai: propan-2-ol me CH3-CH(OH)- group hai, isliye ye I2/NaOH ke saath yellow iodoform precipitate deta hai; propan-1-ol nahi deta kyunki usme wo structural pattern nahi hai.
Important Equations — Ek Nazar Me
| Test / Reaction | Reagent / Condition | Result / Product |
|---|---|---|
| Lucas test — 3° alcohol | conc. HCl + anhyd. ZnCl2 | Turbidity turant (minutes me, room temp) |
| Lucas test — 2° alcohol | conc. HCl + anhyd. ZnCl2 | Turbidity 5-10 min me (warming pe) |
| Lucas test — 1° alcohol | conc. HCl + anhyd. ZnCl2 | Turbidity sirf heating ke baad |
| Ferric chloride test | neutral aq. FeCl3 | Violet/purple colour (sirf phenol deta hai, alcohol nahi) |
| Kolbe's reaction | NaOH phir CO2 (400K, 4-7 atm), phir dil. acid | Salicylic acid (ortho-hydroxybenzoic acid) |
| Reimer-Tiemann reaction | CHCl3 + aq. NaOH, heat | Salicylaldehyde (via dichlorocarbene intermediate) |
| Williamson ether synthesis | Sodium alkoxide + 1° alkyl halide (SN2) | Ether (bulky/3° halide se elimination dominate karta hai) |
| Intermolecular dehydration | excess alcohol + conc. H2SO4, 413 K | Ether |
| Intramolecular dehydration | conc. H2SO4, 443 K | Alkene (Zaitsev product major) |
↔ Table ko side me swipe karein
| Acidity order factor | Effect |
|---|---|
| Electron-withdrawing group (-NO2, -Cl, -CHO) on phenol | Acidity BADHATI hai — phenoxide extra stabilise hota hai; effect ortho/para pe strongest |
| Electron-donating group (-CH3, -OCH3, -NH2) on phenol | Acidity GHATTI hai — phenoxide destabilise hota hai |
| General order | p-nitrophenol > phenol > p-cresol; phenol > water > ethanol |
↔ Table ko side me swipe karein
Common Mistakes — Yahan Marks Kat te Hain
- Galat acidity order likhna. Bahut students phenol ko ethanol se kam acidic likh dete hain — yaad rakho phenoxide resonance-stabilised hota hai isliye phenol (pKa ~10) alcohol (pKa ~16) se zyada acidic hai.
- Substituted phenol acidity me EWG/EDG confuse karna. Electron-withdrawing groups (NO2, Cl) acidity BADHATE hain (stabilise phenoxide), electron-donating groups (CH3, OCH3) acidity GHATATE hain — ulta likhna common galti hai.
- Lucas test ka timing galat yaad rakhna. 3° sabse fast turbidity deta hai (carbocation sabse stable), 1° sabse slow — students kabhi-kabhi ulta order likh dete hain.
- Williamson synthesis me bulky alkyl halide use karna. Unsymmetrical ether banane ke liye hamesha primary (1°) alkyl halide lena chahiye — agar 2°/3° halide diya to elimination (alkene) major product ban jaata hai, ether nahi.
- Phenol ko simple alcohol ki tarah treat karna reactions me. Phenol electrophilic substitution (ring reactions) deta hai kyunki -OH ring ko activate karta hai — students isse simple nucleophilic substitution jaisa answer likh dete hain jo galat hai.
- 3° alcohol ko bhi carboxylic acid me oxidise hota bata dena. 3° alcohol ke alpha-carbon pe H nahi hota isliye normal oxidation (KMnO4/K2Cr2O7) me ye resist karta hai — ye point exam me exceptions section me poocha jaata hai.
Board-Style Important Questions
- 1 mark: Phenol aur ethanol me se kaun zyada acidic hai aur kyun (ek line reason)?
- 2 marks: Lucas test likho — reagent, aur kaise 1°, 2°, 3° alcohols ko distinguish karta hai.
- 2 marks: Kolbe's reaction likho reagents aur conditions ke saath.
- 3 marks: Reimer-Tiemann reaction ka mechanism outline karo aur product identify karo.
- 3 marks: Following substituted phenols ko increasing acidity order me arrange karo aur reason do: phenol, p-nitrophenol, p-cresol.
- 5 marks: Cumene process se phenol banane ki poori sequence likho, aur Williamson ether synthesis ka mechanism (SN2) explain karo unsymmetrical ether ke case me.
Aksar Poochhe Jaane Wale Sawaal
Phenol acidic kyun hota hai jabki alcohol nahi?
Phenol H+ chodne ke baad phenoxide ion banata hai jiska negative charge resonance se ring ke ortho/para carbons tak delocalise ho jaata hai, jo isse stable banata hai. Alcohol ka alkoxide ion resonance nahi kar sakta kyunki uske paas pi-system nahi hai, isliye alcohol kam acidic hota hai.
Lucas test se 1°, 2°, 3° alcohol kaise pehchante hain?
Lucas reagent (conc. HCl + ZnCl2) alcohol ko alkyl chloride me convert karta hai. 3° alcohol fastest reaction deta hai (turbidity minutes me), 2° medium speed, aur 1° sabse slow (sirf heating ke baad turbidity aati hai) — kyunki carbocation stability 3° > 2° > 1° hoti hai.
Ether ka boiling point alcohol se kam kyun hota hai?
Ether me oxygen ke sath directly H nahi juda hota, isliye intermolecular hydrogen bonding nahi ban paati — sirf weak dipole-dipole forces hote hain. Alcohol me -OH group H-bonding banata hai jo extra intermolecular attraction deta hai, isliye alcohol ka boiling point zyada hota hai.
Kolbe's aur Reimer-Tiemann reaction me kya farak hai?
Dono hi phenoxide ion ke ortho position pe electrophile attack karte hain, lekin Kolbe's reaction me electrophile CO2 hota hai (product: salicylic acid) jabki Reimer-Tiemann me electrophile dichlorocarbene (:CCl2 from CHCl3 + NaOH) hota hai (product: salicylaldehyde).
Williamson synthesis me primary alkyl halide hi kyun use karte hain?
Williamson synthesis SN2 mechanism follow karta hai jisme alkoxide nucleophile backside attack karta hai. Bulky (2°/3°) alkyl halide steric hindrance ki wajah se SN2 favour nahi karte — instead alkoxide base ki tarah act karke elimination (E2) de deta hai, isliye ether ki jagah alkene ban jaata hai.
Ferric chloride test kya check karta hai?
Ye test phenolic -OH group identify karta hai. Phenol neutral FeCl3 solution ke saath violet/purple colour complex banata hai. Simple alcohols ye colour nahi dete, isliye ye test phenol ko alcohol se distinguish karne ke liye use hota hai.
Class 12 Chemistry — Saare Chapters
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