Alcohols, Phenols and Ethers: Class 12 Chemistry Chapter 7 Hinglish mein

Chemistry Part 2 · Hinglish notes, simulations aur practice · Official NCERT chapter PDF ↗

Published 12 Oct 2026 · Updated 12 Oct 2026

100 min
1 simulation
48 practice questions
39 MCQs

Is chapter mein aap kya seekhenge

Alcohols, phenols aur ethers ko classify karna aur unhe common aur IUPAC rules se naam dena
Oxygen par bonding aur bond angles ko alcohols, phenols aur ethers ki structures se jodna
Alkenes, carbonyl compounds aur Grignard reagents se alcohols, aur benzene derivatives aur cumene se phenol banane ke liye reagents chunna
Boiling points aur solubility ko hydrogen bonding, chain length aur branching ke basis par samjhana
Alcohols aur phenols ki acidity compare karna aur predict karna ki ring substituents use kaise badalte hain
Alcohols ke esterification, substitution, dehydration aur oxidation, aur phenol ke electrophilic substitution, Kolbe aur Reimer–Tiemann reactions ke products predict karna
Samjhana ki methanol aur ethanol kaise bante hain aur kahan use hote hain, aur methanol zehreela kyun hai
Dehydration ya Williamson synthesis se ether synthesis plan karna, aur ether cleavage aur aryl ethers mein substitution ke products predict karna

NCERT Chemistry Class 12, Chapter 7, pp. 193–226 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Hand sanitiser ki ek boond dabao to tumhe ek alcohol ki smell aati hai, aksar ethanol ya propan-2-ol. Dukhte daant par clove oil lagao to tum eugenol use kar rahe ho, ek phenol jismein ek ether group bhi hai. Refiners ne petrol mein MTBE, ek ether, milaya hai taaki woh smoothly jale. Teenon mein ek cheez common hai: ek oxygen atom jiske dono taraf ek-ek single bond hai.

Ek alcohol mein –OH group kisi alkyl group ke $s p^{3}$ carbon par hota hai, jise $R - O H$ likhte hain. Ek phenol mein –OH seedha aromatic ring ke carbon se juda hota hai, $A r - O H$ . Ek ether mein oxygen do carbon groups ke beech hota hai, $R - O - R^{'}$ , jahan har group alkyl ya aryl ho sakta hai. Teenon families ko ek saath samajhne ka ek badhiya tareeka hai: water se shuru karo aur uske hydrogen atoms ko carbon groups se replace karo (Fig. 7.1).

4/4Carbon groups dono H atoms ko replace karte hain: ether, $R - O - R^{'}$ .

Fig. 7.1Water ka ek hydrogen carbon group se replace karo to alcohol ya phenol milta hai; dono replace karo to ether.NCERT Unit ki shuruaat · p. 193

Upar beech mein do lone pairs wala ek bent oxygen atom hai, jiska har taraf ek bond hai. Step 1 mein oxygen par do hydrogen atoms hain: water. Step 2 mein left wala hydrogen ethyl group se replace hota hai, aur alcohol (ethanol) milta hai. Step 3 mein left par uski jagah benzene ring aati hai, aur phenol milta hai. Step 4 mein left par ethyl group aur right par methyl group hai, aur ether, methoxyethane, milta hai. Har baar jo group badla hai woh shaded hai.

Yeh unit teenon families ko classification aur naming, oxygen ke around shapes, banane ke tareekon, physical properties aur reactions tak follow karti hai, aur un do alcohols par khatam hoti hai jinhe industry million tonnes mein banati hai.

7.1 Classification

Is unit ke lagbhag har compound ko do sawaal sort kar dete hain. Usmein kitne –OH groups hain? Aur har –OH kis tarah ke carbon par hai?

7.1.1 Alcohols — Mono, Di, Tri ya Polyhydric alcohols

Pehle –OH groups gino. Ek –OH ho to compound monohydric hai, do ho to dihydric, teen ho to trihydric, aur teen se zyada ho to polyhydric. Aam taur par har –OH alag carbon atom par hota hai; jis carbon par do –OH groups hon, woh aksar turant water kho deta hai.

Table 7.1Hydroxyl groups ki ginti

OH groups	Example
ek (monohydric)	$(C H_{3})_{2} C H O H$ , propan-2-ol, sanitisers mein
do (dihydric)	$C H_{3} C H (O H) C H_{2} O H$ , propane-1,2-diol
teen (trihydric)	$H O C H_{2} C H (O H) C H_{2} O H$ , glycerol
chhah (polyhydric)	$C_{6} H_{8} (O H)_{6}$ , sorbitol, ek sweetener

Monohydric alcohols ko aage us carbon se sort karte hain jis par –OH hai. Jab woh carbon $s p^{3}$ hybridised ho, to uske neighbours dekho (Fig. 7.2):

Primary (1°): –OH wala carbon sirf ek doosre carbon se bonded hai (methanol mein kisi se nahi), jaise ethanol mein.
Secondary (2°): woh do carbons se bonded hai, jaise propan-2-ol mein.
Tertiary (3°): woh teen carbons se bonded hai, jaise 2-methylpropan-2-ol mein.
Allylic: woh C=C double bond ke bagal wala $s p^{3}$ carbon hai, jaise but-2-en-1-ol, $C H_{3} C H = C H C H_{2} O H$ , mein.
Benzylic: woh benzene ring ke bagal wala $s p^{3}$ carbon hai, jaise 1-phenylethanol, $C_{6} H_{5} C H (O H) C H_{3}$ , mein.

Dhyaan do ki allylic aur benzylic neighbour ka naam batate hain, degree ka nahi, isliye dono labels saath lag sakte hain: but-2-en-1-ol ek primary allylic alcohol hai, aur 1-phenylethanol ek secondary benzylic alcohol.

3/62-Methylpropan-2-ol: teen carbon neighbours.

Fig. 7.2–OH wala carbon, aur woh kis-kis se bonded hai, yahi class decide karta hai.NCERT p. 194

Har step mein ek alcohol hai jiska OH wala carbon circle kiya hai aur uske carbon neighbours box mein hain. Step 1, ethanol: ek carbon neighbour, primary. Step 2, propan-2-ol: do carbon neighbours, secondary. Step 3, 2-methylpropan-2-ol: teen methyl neighbours, tertiary. Step 4, but-2-en-1-ol: OH carbon ek C=C ke bagal mein hai, allylic. Step 5, 1-phenylethanol: OH carbon benzene ring ke bagal mein hai, benzylic. Step 6, prop-1-en-2-ol: OH khud C=C ke ek carbon par hai, vinylic.

Jab –OH kisi C=C bond ke $s p^{2}$ carbon par ho, to compound ek vinylic alcohol hai, jise enol bhi kehte hain. Simple enols tikte nahi: hydrogen oxygen se bagal wale carbon par chala jaata hai, isliye prop-1-en-2-ol turant rearrange hokar propanone ban jaata hai. Phenols mein bhi –OH ek $s p^{2}$ carbon par hota hai, lekin wahan aromatic ring structure ko stable rakhti hai.

7.1.2 Phenols — Mono, Di aur trihydric phenols

Phenols bhi isi tarah gine jaate hain. Phenol khud aur thymol, woh phenol jo ajwain ke beejon ko unki tez smell deta hai, monohydric hain. Teenon benzenediols (catechol, resorcinol aur hydroquinone) dihydric hain, aur benzene-1,2,3-triol (pyrogallol), jo kabhi photographs develop karne mein use hota tha, trihydric hai.

7.1.3 Ethers

Ethers ke liye oxygen par lage do groups dekho. Dono groups same hon to symmetrical (simple) ether banta hai, jaise methoxymethane, $C H_{3} O C H_{3}$ , ya diphenyl ether, $C_{6} H_{5} O C_{6} H_{5}$ . Do alag groups hon to unsymmetrical (mixed) ether banta hai, jaise methoxybenzene, $C_{6} H_{5} O C H_{3}$ , ya MTBE, $C H_{3} O C (C H_{3})_{3}$ .

Quick check

3 mein se 1

Glycerol,

H O C H_{2} C H (O H) C H_{2} O H

, ka sabse sahi description hai

ek trihydric alcohol jismein do 1° aur ek 2° –OH hainek trihydric alcohol jismein teen 1° –OH groups hainek dihydric alcoholek trihydric phenol

Answer dekho

Answer (A) ek trihydric alcohol jismein do 1° aur ek 2° –OH hain

Teen –OH groups ise trihydric banate hain. Dono end carbons ka ek-ek carbon neighbour hai (1°); beech wale carbon ke do hain (2°). Ismein koi ring nahi hai, isliye yeh phenol nahi hai.

7.2 Nomenclature

Is unit ke zyaadatar compounds ke do naam jaanne layak hain: ek common name jo tumhe labels aur purani books mein milta hai, aur systematic IUPAC name, jisse tum structure bana sakte ho.

Alcohols ka naamkaran

Alcohols ke common names do words ke hote hain: pehle alkyl group ka naam, phir alcohol. Isliye $(C H_{3})_{2} C H O H$ isopropyl alcohol hai aur $C_{6} H_{5} C H_{2} O H$ benzyl alcohol hai.

IUPAC system mein alcohol ko ek substituted alkane ki tarah naam dete hain jiska aakhri -e badalkar -ol ho jaata hai. Zyaadatar kaam chaar rules karte hain:

Sabse lambi carbon chain chuno jismein –OH wala carbon ho.
Chain ko us end se number karo jisse –OH carbon ko chhota locant mile, chahe phir kisi branch ko bada number mile.
Baaki substituents ko prefixes ki tarah alphabetical order mein lagao, har ek ke saath uska locant.
Do ya zyada –OH groups ke liye alkane ka -e rakho aur -diol, -triol waghairah jodo, har locant ke saath: $H O (C H_{2})_{4} O H$ butane-1,4-diol hai.

Ring mein –OH wala carbon C1 hota hai, aur ring ko us direction mein number karte hain jisse agle substituent ko chhota locant mile: do carbon aage ek methyl group ho to naam 3-methylcyclohexan-1-ol banta hai, jise aksar chhota karke 3-methylcyclohexanol likhte hain. Fig. 7.3 ek naam step by step banata hai.

4/4Prefix, parent, locant aur suffix: 5-methylhexan-3-ol.

Fig. 7.3–OH numbering ki direction tay karta hai.NCERT p. 196

Chhah carbon groups ki ek zig-zag chain hai, jismein left se doosre carbon par methyl branch aur chauthe par OH group hai. Step 1 mein OH carbon wali sabse lambi chain shaded hai: chhah carbons, isliye parent hexane hai. Step 2 mein chain right end se number hoti hai, jisse OH carbon ko 4 ki jagah number 3 milta hai. Step 3 mein methyl branch circle hoti hai, jo ab carbon 5 par hai. Step 4 mein poora naam dikhta hai, 5-methylhexan-3-ol.

Table 7.2Kuch alcohols ke common aur IUPAC namesNCERT Table 7.1 · p. 196

Formula	Common; IUPAC
$(C H_{3})_{2} C H$ – $C H_{2} C H_{2} O H$	isopentyl alcohol; 3-methylbutan-1-ol
$(C H_{3})_{3} C$ – $C H_{2} O H$	neopentyl alcohol; 2,2-dimethylpropan-1-ol
$(C H_{3})_{2} C (O H)$ – $C_{2} H_{5}$	tert-pentyl alcohol; 2-methylbutan-2-ol
$C H_{2} = C H C H_{2} O H$	allyl alcohol; prop-2-en-1-ol
$C_{6} H_{5} C H_{2} O H$	benzyl alcohol; phenylmethanol
$C H_{3} C H (O H)$ – $C H_{2} O H$	propylene glycol; propane-1,2-diol
$C_{5} H_{9} O H$ (ring)	cyclopentyl alcohol; cyclopentanol

Phenols ka naamkaran

Phenol, $C_{6} H_{5} O H$ , parent compound ka common aur IUPAC dono naam hai. Substituted phenol mein –OH wala ring carbon C1 hota hai. Ring par do groups ke liye purane names o-, m- aur p- prefixes use karte hain (ortho = 1,2; meta = 1,3; para = 1,4), aur methylphenols ka apna naam hai, cresols.

Table 7.3Kuch phenols ke naamNCERT p. 197

Structure	Common; IUPAC
$m$ - $C H_{3} C_{6} H_{4} O H$	m-cresol; 3-methylphenol
$o$ - $C_{6} H_{4} (O H)_{2}$	catechol; benzene-1,2-diol
$m$ - $C_{6} H_{4} (O H)_{2}$	resorcinol; benzene-1,3-diol
$p$ - $C_{6} H_{4} (O H)_{2}$	hydroquinone (quinol); benzene-1,4-diol
C1 par OH, C2 par isopropyl, C5 par methyl	thymol; 2-isopropyl-5-methylphenol

Ethers ka naamkaran

Ether ka common name dene ke liye oxygen par lage do groups ko alphabetical order mein likho aur aakhir mein ether lagao: $C_{6} H_{5} O C H_{2} C H_{3}$ ethyl phenyl ether hai. Do same groups hon to prefix di lagta hai, jaise dipropyl ether.

IUPAC name ke liye bada group, ya ring, parent hydrocarbon chuno aur baaki sab ko, oxygen samet, alkoxy (–OR) ya aryloxy (–OAr) prefix ki tarah naam do: $C H_{3} O C H_{2} C H_{3}$ methoxyethane hai aur $C_{6} H_{5} O C H_{2} C H_{2} C H_{3}$ propoxybenzene hai. Agar molecule mein ek –OH group bhi ho, to suffix –OH ko milta hai aur ether wala hissa prefix ban jaata hai.

Table 7.4Kuch ethers ke common aur IUPAC namesNCERT Table 7.2 · p. 197

Formula	Common; IUPAC
$C H_{3} O$ – $C (C H_{3})_{3}$	tert-butyl methyl ether (MTBE); 2-methoxy-2-methylpropane
$C_{2} H_{5} O$ – $(C H_{2})_{3} C H_{3}$	butyl ethyl ether; 1-ethoxybutane
$C_{6} H_{5} O$ – $C H_{2} C H_{2} C H_{3}$	phenyl propyl ether; propoxybenzene
$C_{6} H_{5} O C_{6} H_{5}$	diphenyl ether; phenoxybenzene

Example 7.1NCERT Example 7.1 · p. 198

Structures se naam dena

Har compound ka IUPAC name batao.

$(C H_{3})_{2} C (O H) C H_{2}$ – $C H (C l) C H_{3}$
$C H_{3} C H_{2} O C H (C H_{3}) C H_{2} C H_{3}$
ek phenol jismein Cl, –OH ke para position par hai aur $C H_{3}$ , Cl ke bagal mein
$C H_{3} O C H_{2} C H_{2} O H$

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Practice · 1 question

Practice: naamkaran: answers ke saath

1
Short answerMediumNCERT Intext Question 7.3
Har compound ka IUPAC name likho.
1. $C H_{3} C H (O H) C H_{2}$ – $C H (C H_{3}) C H_{2} C H_{3}$
  Solution dikhao
  4-Methylhexan-2-ol: six-carbon chain ethyl end se hokar jaati hai; left se number karne par –OH ko locant 2 milta hai.
2. $H O C H_{2} C H (C H_{3})$ – $C H (O H) C H_{3}$
  Solution dikhao
  2-Methylbutane-1,3-diol: –OH locants {1,3}, {2,4} se behtar hain.
3. ek cyclopentane ring jiske ek carbon par –OH aur agle par Br hai
  Solution dikhao
  2-Bromocyclopentan-1-ol (2-bromocyclopentanol): –OH carbon C1 hai.
4. $C H_{2} = C H C H_{2}$ – $C H (O H) C H_{3}$
  Solution dikhao
  Pent-4-en-2-ol: right se number karo taaki –OH ko 2 mile; tab double bond C4 se shuru hota hai.
5. $C H_{3} C \equiv C C H_{2} O H$
  Solution dikhao
  But-2-yn-1-ol: –OH C1 par, triple bond C2 aur C3 ke beech.

7.3 Functional Groups ki Structures

Water se shuru karo. Iska oxygen $s p^{3}$ hybridised hai: do hybrid orbitals hydrogen atoms se bond karte hain aur do mein lone pairs hain. Lone pairs bonding pairs se zyada jagah lete hain, isliye woh H–O–H angle ko 104.5° tak band kar dete hain, jo tetrahedral 109.5° se kaafi kam hai (Fig. 7.4).

Ek hydrogen ko methyl group se badlo to methanol milta hai. Oxygen ab bhi $s p^{3}$ hai, aur C–O–H angle khulkar lagbhag 109° ho jaata hai, ab bhi tetrahedral se thoda kam. Doosra hydrogen bhi badlo to methoxymethane milta hai, aur dono methyl groups ek doosre ko itna crowd karte hain ki C–O–C angle 111.7° tak pahunch jaata hai, tetrahedral se thoda upar. Is ether ka har C–O bond 141 pm lamba hai, jo methanol ke C–O bond se lagbhag ek picometre tak match karta hai.

Phenol mein farak carbon par hai, oxygen par nahi. Iska –OH ek $s p^{2}$ ring carbon se juda hai, aur C–O bond chhota hokar 136 pm ho jaata hai (methanol: 142 pm). $s p^{2}$ orbital mein s character zyada hota hai aur woh apne bonding pair ko paas rakhta hai, aur oxygen ka ek lone pair ring ke saath share hota hai, jisse C–O bond mein thoda double-bond character aa jaata hai (phenols ki acidity).

3/4C–O–C 111.7° hai: do methyl groups ek doosre ko crowd karte hain.

Fig. 7.4Lone pairs oxygen par angle band karte hain; bulky groups use kholte hain.NCERT Fig. 7.1 · p. 198

Do lone pairs wala ek oxygen atom bana hai jiske do bonds neeche ki taraf hain. Step 1, water: do hydrogens 104.5 degrees par, lone pairs se dabe hue. Step 2, methanol: ek methyl group aur ek hydrogen lagbhag 109 degrees par. Step 3, methoxymethane: do methyl groups 111.7 degrees par, apne bulk se door dhakele hue. Step 4, phenol: oxygen par ek benzene ring aur ek hydrogen, aur C–O bond par 136 pm likha hai, jo methanol ke 142 pm bond se chhota hai.

Quick check

3 mein se 1

Oxygen par bond angle ke hisaab se arrange karo, sabse chhota pehle.

methoxymethane mein C–O–C
water mein H–O–H
methanol mein C–O–H

Answer dekho

Answer

water mein H–O–H
methanol mein C–O–H
methoxymethane mein C–O–C

Lone-pair repulsion water ko sabse zyada dabata hai (104.5°); ek H ko

C H_{3}

se badalne par angle lagbhag 109° tak khulta hai; do methyl groups use 111.7° tak dhakel dete hain.

7.4 Alcohols aur Phenols

Ab hum dekhenge ki alcohols aur phenols kaise bante hain, unke boiling aur dissolve hone ka tareeka aisa kyun hai, aur woh kaise react karte hain.

7.4.1 Alcohols ka Preparation

Alkenes se

Acid-catalysed hydration. Jab dilute sulphuric acid jaisa koi acid catalyst ki tarah maujood ho, to water C=C bond ke across add hota hai. Unsymmetrical alkene mein hydrogen us carbon par jaata hai jis par pehle se zyada hydrogens hain aur –OH doosre carbon par (Markovnikov's rule), kyunki is order mein zyada stable carbocation banta hai.

\begin{aligned} (C H_{3})_{2} C = C H_{2} \\ + H_{2} O \overset{H^{+}}{\to} \\ (C H_{3})_{3} C - O H \end{aligned}

(7.1)

Mechanism mein teen steps hain (Fig. 7.5). Pehle, C=C ke π electrons $H_{3} O^{+}$ se ek proton le lete hain. Proton $C H_{2}$ end par jaata hai, isliye positive charge us carbon par aata hai jis par zyada alkyl groups hain. Doosre, ek water molecule apne lone pair se cationic carbon se bond karta hai, aur protonated alcohol (oxonium ion) banta hai. Teesre, ek aur water molecule extra proton hata deta hai; alcohol banta hai aur $H_{3} O^{+}$ wapas mil jaata hai.

2/4Water ka ek lone pair positive carbon se bond karta hai.

Fig. 7.5Protonate karo, water add karo, proton nikaalo: acid ek catalyst hai.NCERT p. 199

Step 1 mein 2-methylpropene ek hydronium ion ke bagal mein hai, aur ek curved arrow C=C bond se hydronium ion ke ek hydrogen tak jaata hai, aur doosra arrow O–H bond ke electrons ko oxygen ki taraf jaate dikhata hai. Step 2 mein tertiary carbocation, (CH3)3C+, hai, aur ek curved arrow water molecule ke lone pair se positive carbon tak jaata hai. Step 3 mein oxonium ion hai, aur ek doosra water molecule oxygen par lage hydrogens mein se ek ko kheench raha hai. Step 4 mein products hain: 2-methylpropan-2-ol aur wapas bana hydronium ion.

Hydroboration–oxidation. Yeh do-stage route woh alcohol deta hai jo acid hydration nahi de sakta. Pehle, borane, $B H_{3}$ (jo apne dimer, diborane, $B_{2} H_{6}$ , ke roop mein diya jaata hai), C=C ke across add hota hai. Boron kam substituted carbon se bond karta hai, yaani jis par zyada hydrogens aur kam crowding hai, jabki ek hydrogen doosre carbon par jaata hai; har borane teen alkenes lekar trialkylborane banata hai. Doosre, alkaline hydrogen peroxide har C–B bond ko C–OH bond se badal deta hai. Kul milakar H aur OH double bond ke across anti-Markovnikov tareeke se lagte hain, aur side products bahut kam bante hain. Yeh hai hydroboration–oxidation.

\begin{aligned} 3 R C H = C H_{2} + B H_{3} \\ \overset{}{\to} (R C H_{2} C H_{2})_{3} B \\ \to_{O H^{-}}^{H_{2} O_{2}} 3 R C H_{2} C H_{2} O H \end{aligned}

(7.2)

Compare

Ek alkene, do alag alcohols

Acid-catalysed hydration

$(C H_{3})_{2} C = C H_{2}$ se 2-methylpropan-2-ol milta hai
–OH zyada substituted carbon par aata hai
carbocation se hokar jaata hai, jo rearrange ho sakta hai

Hydroboration–oxidation

$(C H_{3})_{2} C = C H_{2}$ se 2-methylpropan-1-ol milta hai
–OH kam substituted carbon par aata hai
koi carbocation nahi, isliye koi rearrangement nahi

Carbonyl compounds se

Aldehydes aur ketones ka reduction. Reduction C=O group mein do hydrogen atoms add karta hai, ek carbon par aur ek oxygen par. Starting compound product tay karta hai: aldehyde ka –CHO $- C H_{2} O H$ ban jaata hai, yaani primary alcohol, aur ketone ka C=O CH–OH ban jaata hai, yaani secondary alcohol. Bade scale par hydrogen gas aur metal catalyst (Ni, Pd ya Pt) yeh kaam karte hain; laboratory mein hydride donors sodium borohydride, $N a B H_{4}$ , aur lithium aluminium hydride, $L i A l H_{4}$ , zyada convenient hain.

\begin{aligned} R C H O \to_{N i}^{H_{2}} R C H_{2} O H \\ aur \\ R_{2} C = O \\ \overset{N a B H_{4}}{\to} R_{2} C H O H \end{aligned}

(7.3)

Carboxylic acids aur esters ka reduction. –COOH group ko reduce karna mushkil hai: $N a B H_{4}$ use chhoota tak nahi, aur sirf kaafi zyada strong $L i A l H_{4}$ , uske baad water, use $- C H_{2} O H$ mein badalta hai. Neeche arrow par likhe do numbers ka matlab hai: pehla reagent daalo, woh reaction poora hone do, phir doosra daalo. Bulk chemicals ke liye $L i A l H_{4}$ bahut mehenga hai, isliye manufacturers ek doosra raasta lete hain: woh acid ka ester banate hain aur ester ko metal catalyst par hydrogenate karte hain.

\begin{aligned} R C O O H \\ \to_{2 \cdot H_{2} O}^{1 \cdot L i A l H_{4}} R C H_{2} O H \end{aligned}

(7.4)

Grignard reagents se

Grignard reagent, $R^{'} M g X$ , mein partial negative charge wala ek carbon magnesium se bonded hota hai. Woh carbon carbonyl group ke partly positive carbon par attack karta hai (nucleophilic addition) aur ek naya C–C bond banata hai, jisse magnesium alkoxide, yaani adduct, milta hai. Phir water ya dilute acid adduct ko hydrolyse karke alcohol deta hai.

\begin{aligned} R_{2} C = O + R^{'} M g X \\ \overset{}{\to} R_{2} C (R^{'}) O M g X \\ \overset{H_{2} O}{\to} R_{2} C (R^{'}) O H \\ + M g (O H) X \end{aligned}

(7.5)

Carbonyl partner alcohol ki class tay karta hai (Fig. 7.6): methanal se primary alcohol milta hai, kisi aur aldehyde se secondary alcohol, aur ketone se tertiary alcohol. Kyunki chain R′ group se badhti bhi hai, isliye carbon skeleton banane ka yeh sabse useful tareekon mein se ek hai.

3/3Propanone se 2-methylbutan-2-ol milta hai, ek 3° alcohol.

Fig. 7.6Methanal → 1°, baaki aldehydes → 2°, ketones → 3°.NCERT p. 201

Teen rows mein same Grignard reagent, ethylmagnesium bromide aur uske baad water, teen carbonyl compounds se react karta dikhta hai. Row 1: methanal se propan-1-ol milta hai, ek primary alcohol. Row 2: ethanal se butan-2-ol milta hai, ek secondary alcohol. Row 3: propanone se 2-methylbutan-2-ol milta hai, ek tertiary alcohol. Har step ek row ko shade karta hai.

Example 7.2NCERT Example 7.2 · p. 201

Teen reactions se alcohols predict karna

Har reaction ke main product ki structure aur IUPAC name batao.

Pentan-3-one sodium borohydride ke saath.
2-Methylbut-2-ene, $(C H_{3})_{2} C = C H C H_{3}$ , water aur dilute sulphuric acid ke saath.
Cyclohexanone methylmagnesium iodide ke saath, phir water.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Example

Grignard synthesis plan karna

Grignard reagent aur carbonyl compound ke do alag pairs suggest karo jo 2-methylbutan-2-ol, $(C H_{3})_{2} C (O H) C H_{2} C H_{3}$ , dete hain.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

7.4.2 Phenols ka Preparation

Phenol ka pehla source coal tar tha, aur yeh carbolic acid naam se bikta tha. Aaj ka phenol uski jagah benzene aur uske derivatives se banta hai; Fig. 7.7 chaar routes dikhata hai.

Haloarenes se. Sodium hydroxide chlorobenzene se chlorine ko sirf bahut sakht conditions mein hatata hai: lagbhag 623 K aur kareeb 300 atm. Isse pata chalta hai ki aryl C–Cl bond substitution ka kitni mazbooti se virodh karta hai. Result sodium phenoxide hai; acid daalne par phenol free ho jaata hai.
Benzenesulphonic acid se. Yahan chlorine ki jagah $- S O_{3} H$ group nikalta hai. Benzene aur oleum (fuming sulphuric acid) se benzenesulphonic acid milta hai; ise solid NaOH ke saath fuse karne par sulphonate group –O⁻ se badal jaata hai, aur acid phenoxide ko phenol bana deta hai.
Diazonium salts se. Thanda nitrous acid ( $N a N O_{2}$ aur HCl se, 273–278 K par rakha hua) aniline ko benzenediazonium chloride mein badalta hai. Yeh salt sirf thand mein stable hai: solution garam karo to nitrogen bulbulon mein nikal jaati hai aur ring par uski jagah water aa jaata hai, jisse phenol milta hai. Diazonium salts tumhe Unit 9 mein phir milenge.
Cumene se. Industry ka favourite route cumene (isopropylbenzene) se shuru hota hai, jo khud benzene aur propene se banta hai. Cumene mein se air guzaarne par cumene hydroperoxide banta hai; phir dilute acid use phenol aur propanone mein tod deta hai. Ek process se do bikne layak products milne se cost kam rehti hai, aur aaj banne wala zyaadatar phenol isi route se aata hai.

\begin{aligned} C_{6} H_{5} C l + N a O H \\ \to_{h i g h P}^{623 K} C_{6} H_{5} O N a \\ \overset{H^{+}}{\to} C_{6} H_{5} O H \end{aligned}

(7.6)

\begin{aligned} C_{6} H_{6} \overset{o l e u m}{\to} \\ C_{6} H_{5} S O_{3} H \\ \to_{f u s e}^{N a O H} C_{6} H_{5} O N a \\ \overset{H^{+}}{\to} C_{6} H_{5} O H \end{aligned}

(7.7)

\begin{aligned} C_{6} H_{5} N H_{2} \to_{H C l}^{N a N O_{2}} \\ C_{6} H_{5} N_{2}^{+} C l^{-} \\ \to_{w a r m}^{H_{2} O} C_{6} H_{5} O H \\ + N_{2} ↑ + H C l \end{aligned}

(7.8)

\begin{aligned} C_{6} H_{5} C H (C H_{3})_{2} \overset{O_{2}}{\to} \\ C_{6} H_{5} C (C H_{3})_{2} O O H \\ \to_{H_{2} O}^{H^{+}} C_{6} H_{5} O H \\ + C H_{3} C O C H_{3} \end{aligned}

(7.9)

4/4Cumene air ke saath, phir dilute acid: phenol aur propanone.

Fig. 7.7Phenol tak chaar routes; cumene route propanone bhi deta hai.NCERT p. 202

Beech mein ek phenol ring hai. Chaar konon se arrows us tak aate hain: chlorobenzene (upar left, NaOH ke saath 623 K par phir acid), aniline se bana benzenediazonium chloride (upar right, water ke saath garam), benzenesulphonic acid (neeche left, NaOH ke saath fuse phir acid) aur cumene (neeche right, air phir dilute acid, aur doosre product ke roop mein propanone). Har step ek route ko shade karta hai.

Practice · 2 questions

Practice: alcohols banana: answers ke saath

1
Short answerMediumNCERT Intext Question 7.4
Kaun sa Grignard reagent, methanal mein daal kar aur uske baad water se, har alcohol deta hai?
1. $(C H_{3})_{2} C H C H_{2} C H_{2} O H$
  Solution dikhao
  $C H_{2} O H$ hatao: Grignard reagent $(C H_{3})_{2} C H C H_{2} M g B r$ hai, jo 3-methylbutan-1-ol deta hai.
2. $C_{6} H_{5} C H_{2} C H_{2} O H$
  Solution dikhao
  Benzylmagnesium chloride, $C_{6} H_{5} C H_{2} M g C l$ , methanal ke saath 2-phenylethanol deta hai.
2
Short answerMediumNCERT Intext Question 7.5
Har reaction ka main organic product likho.
1. $C H_{3} C H_{2} C H = C H_{2}$ $H_{2} O$ / $H^{+}$ ke saath
  Solution dikhao
  Butan-2-ol, $C H_{3} C H_{2}$ – $C H (O H) C H_{3}$ , kyunki –OH andar wale carbon par jaata hai.
2. $C H_{3} C O C H_{2}$ – $C H_{2} C O O C H_{3}$ $N a B H_{4}$ ke saath
  Solution dikhao
  Sirf ketone reduce hota hai, aur methyl 4-hydroxypentanoate milta hai, $C H_{3} C H (O H)$ – $C H_{2} C H_{2}$ – $C O O C H_{3}$ . Ester bacha rehta hai.
3. $C H_{3} (C H_{2})_{2}$ – $C H (C H_{3}) C H O$ $N a B H_{4}$ ke saath
  Solution dikhao
  Aldehyde primary alcohol ban jaata hai, 2-methylpentan-1-ol: $C H_{3} (C H_{2})_{2}$ – $C H (C H_{3})$ – $C H_{2} O H$ .

7.4.3 Physical Properties

Har molecule ko aise socho: ek water jaisa head, yaani –OH group, ek hydrocarbon tail par laga hai. Head physical behaviour ka pattern tay karta hai; tail use fine-tune karti hai.

Boiling points. Chaar butanols ek badhiya test hain. Sab $C_{4} H_{10} O$ hain, phir bhi butan-1-ol 391 K par boil karta hai, 2-methylpropan-1-ol 381 K par, butan-2-ol 373 K par aur compact, lagbhag gol 2-methylpropan-2-ol 355 K par. Molecule jitna zyada branched hoga, utni kam surface woh apne neighbours se laga paayega, aur van der Waals (dispersion) attraction utna weak hoga. Chain lambi karne se ulta hota hai, isliye boiling points methanol se ethanol, propanol aur aage tak lagaataar badhte hain.

Isse bada effect hydrogen bonding (हाइड्रोजन आबंध) ka hai. Ek molecule ka O–H hydrogen doosre molecule ke oxygen ke lone pair ki taraf attract hota hai, isliye alcohol molecules chains aur clusters mein ek doosre se chipke rehte hain (Fig. 7.8). Boiling ke liye in links ko todna padta hai, jismein extra energy lagti hai.

1/3Har molecule ka O–H hydrogen agle molecule ke oxygen se bond karta hai.

Fig. 7.8Alcohols hydrogen bonds de bhi sakte hain aur le bhi sakte hain; ethers sirf le sakte hain.NCERT p. 203

Step 1 mein teen alcohol molecules, R–O–H, ek diagonal chain mein hain, aur dotted lines har molecule ke H ko agle ke O se jodti hain: molecules ke beech hydrogen bonds. Step 2 mein teen ether molecules, R–O–R prime, bikhre hue hain aur koi dotted line nahi hai, kyunki ether mein O–H hydrogen nahi hota. Step 3 mein ek alcohol molecule hai, jiske oxygen ko ek water molecule hydrogen bond deta hai aur ek doosra water molecule uske O–H se hydrogen bond leta hai.

Table 7.5Milte-julte masses, bahut alag boiling points

Compound (molar mass)	Boiling point
butane (58 g/mol)	273 K
methoxyethane (60 g/mol)	281 K
chloroethane (64.5 g/mol)	285 K
propan-1-ol (60 g/mol)	370 K

Butane, methoxyethane aur propan-1-ol ka molar mass lagbhag same hai, phir bhi alcohol ether se lagbhag 90 K upar boil karta hai. Sirf alcohol ke paas share karne ke liye O–H hydrogen hai. Chloroethane polar hai aur thoda bhaari bhi, lekin hydrogen bonds ke bina woh ether ke aas-paas hi boil karta hai. Isi wajah se alcohols aur phenols milte-julte mass wale hydrocarbons, ethers aur haloalkanes se kaafi upar boil karte hain.

Solubility. Water kisi molecule ko tabhi andar aane deta hai jab woh water ke hydrogen bonds ke network mein shaamil ho sake. –OH head yeh kar sakta hai, hydrogen bonds de bhi sakta hai aur le bhi; hydrocarbon tail nahi kar sakti, aur woh water molecules ko side mein dhakelti hai. Head aur tail ki takkar result tay karti hai. Chhoti tail ho to head seedha jeet jaata hai: methanol, ethanol aur propan-1-ol water mein kisi bhi proportion mein mix ho jaate hain. Tail badhti hai to head haarne lagta hai: 100 mL water mein lagbhag 7 g butan-1-ol ghulta hai, lagbhag 2 g pentan-1-ol aur sirf lagbhag 0.6 g hexan-1-ol.

Try karke dekho

Alcohol kahan jaata hai?

Tumhe chahiye

ethanol (rectified spirit)
butan-1-ol
liquid paraffin
stoppers wali teen test tubes
ek 10 mL measuring cylinder

Pehle guess karo

Kaun si tubes mein do layers dikhengi?

butan-1-ol aur paraffinsirf ethanolteenon

Teen labelled test tubes mein se har ek mein 5 mL water daalo.
Pehli tube mein 2 mL ethanol, doosri mein 2 mL butan-1-ol aur teesri mein 2 mL liquid paraffin daalo.
Har tube par stopper lagao, 20 seconds hilao aur ek minute rakha rehne do.
Dekho ki ek saaf layer hai ya do layers, aur note karo ki kaun si layer upar hai.

Table 7.6Observations

Daala gaya liquid	Ek layer ya do?
Ethanol
Butan-1-ol
Liquid paraffin

Tumhari entries apne aap save hoti hain.

Example 7.3NCERT Example 7.3 · p. 204

Boiling points ki ranking

Har set ko boiling point ke badhte order mein arrange karo aur reason batao.

Hexan-1-ol, 2-methylbutan-2-ol, ethanol, pentan-1-ol, pentan-2-ol.
Butanal, propane-1,2-diol, ethoxyethane, butan-1-ol (molar masses 72–76 g/mol).

Pehle khud try karo. Phir solution ek-ek step karke kholo.

7.4.4 Chemical Reactions

Alcohol apne do polar bonds mein se kisi par bhi react kar sakta hai. Nucleophile ki tarah woh oxygen ke lone pair se kisi electrophile par attack karta hai, aur aakhir mein O–H bond toot jaata hai. Electrophile ki tarah woh pehle apne oxygen par ek proton leta hai; phir protonated alcohol water kho deta hai aur C–O bond toot jaata hai.

Compare

Kaun sa bond tootta hai?

O–H tootta hai

alcohol acid ya nucleophile ki tarah kaam karta hai
alkoxides aur esters deta hai
phenols bhi aise react karte hain

C–O tootta hai

protonated alcohol electrophile hai
alkyl halides aur alkenes deta hai
phenols lagbhag kabhi nahi (sirf zinc dust ke saath)

\begin{aligned} R - O H + H^{+} \\ \overset{}{⇌} R - O H_{2}^{+} \\ R - O H_{2}^{+} + B r^{-} \\ \overset{}{\to} R - B r + H_{2} O \end{aligned}

(7.10)

(a) O–H bond ke cleavage wale reactions

1. Acidity: active metals ke saath reaction. Ethanol mein sodium ka chhota tukda daalo to usmein bubbles uthte hain: hydrogen nikalti hai aur sodium ethoxide solution mein reh jaata hai. Potassium aur aluminium bhi aisa hi karte hain, aur phenol bhi. Propan-2-ol se isi tarah bana aluminium isopropoxide laboratory ka ek useful reagent hai.

\begin{aligned} 2 R - O H + 2 N a \\ \overset{}{\to} 2 R - O^{-} N a^{+} \\ + H_{2} ↑ \end{aligned}

(7.11)

\begin{aligned} 6 (C H_{3})_{2} C H O H \\ + 2 A l \overset{}{\to} \\ 2 [(C H_{3})_{2} C H O]_{3} A l \\ + 3 H_{2} ↑ \end{aligned}

(7.12)

Phenol isse aage jaata hai: woh aqueous sodium hydroxide mein bhi ghul jaata hai aur sodium phenoxide aur water banata hai. Alcohols aqueous NaOH se mushkil se react karte hain. Isliye dono families Brønsted acids (proton donors) hain, lekin phenol zyada strong acid hai.

\begin{aligned} C_{6} H_{5} O H + N a O H \\ \overset{}{\to} C_{6} H_{5} O^{-} N a^{+} \\ + H_{2} O \end{aligned}

(7.13)

Alcohols ki acidity. Alcohol proton de hi kyun paata hai? Oxygen O–H bond ke shared electrons ko apni taraf kheenchta hai, jisse hydrogen thoda positive reh jaata hai, aur kaafi strong base use le sakta hai. Oxygen ke bagal wale carbon par lage alkyl groups electron density ko wapas oxygen ki taraf dhakelte hain (+I effect). Isse O–H bond kam polar hota hai aur banne wala alkoxide ion kam stable. Isliye solution mein acid strength methanol se primary, secondary aur tertiary alcohols tak ghatti hai.

Sodium ethoxide ko water mein daalo to woh tikta nahi: woh water se proton le leta hai, aur ethanol aur hydroxide ions bante hain. Proton transfer zyaadatar weak acid ki taraf chalta hai, isliye is pair mein water zyada strong acid hona chahiye. Sach mein zyaadatar alcohols water se thode weak acids hain (methanol lagbhag barabar hai), aur alkoxide ion hydroxide se zyada strong base hai.

\begin{aligned} R - O^{-} + H_{2} O \\ \overset{}{\to} R - O H + O H^{-} \end{aligned}

(7.14)

Wahi oxygen proton le bhi sakta hai. Concentrated acid mein alcohol kuch had tak apne protonated form, $R O H_{2}^{+}$ , mein rehta hai, isliye alcohols weak Brønsted bases bhi hain, aur yahi protonation un zyaadatar reactions ko shuru karta hai jinmein C–O bond tootta hai.

Phenols ki acidity. Phenol, jiska $p K_{a} \approx 10$ hai, ethanol ( $p K_{a} \approx 16$ ) se lagbhag das lakh guna zyada strong acid hai. $p K_{a} = - \log K_{a}$ . Kam $p K_{a}$ ka matlab zyada strong acid; $p K_{a}$ ki ek unit $K_{a}$ mein 10 ka factor hai. Do baatein iske proton chhodne ke favour mein hain. Pehli, oxygen ek $s p^{2}$ ring carbon se bonded hai, jo $s p^{3}$ carbon se zyada electronegative hai, isliye O–H bond zyada polar hai. Doosri, aur zyada important, phenoxide ion ka negative charge oxygen aur teen ring carbons par phaila hota hai, jabki alkoxide ion mein woh sirf oxygen par rehta hai (Fig. 7.9).

\begin{aligned} C_{6} H_{5} O H + H_{2} O \\ \overset{}{⇌} C_{6} H_{5} O^{-} \\ + H_{3} O^{+} \end{aligned}

(7.15)

5/5Asli ion ek mix hai: charge O aur teen ring carbons mein share hota hai.

Fig. 7.9Resonance phenoxide ke charge ko chaar atoms par phailata hai; alkoxide use ek hi par rakhta hai.NCERT p. 206

Ek phenoxide ion bana hai jismein benzene ring ke upar oxygen hai. Step 1: negative charge oxygen par hai aur ring mein teen alternating double bonds hain. Step 2: oxygen ek C=O double bond banata hai aur negative charge right wale ortho carbon par dikhta hai. Step 3: charge neeche para carbon par chala gaya hai. Step 4: woh left wale doosre ortho carbon par hai. Step 5 mein hybrid dikhta hai: circle wali ek ring, oxygen tak partial double bond, aur oxygen, dono ortho aur ek para carbon par partial negative charges; bagal mein ethoxide hai, jiska charge oxygen par hi rehta hai.

Phenol ke bhi apne resonance structures hain, lekin unmein charge alag hota hai, positive oxygen aur negative ring carbon, jismein energy lagti hai. Phenoxide ion ke saare structures ek negative charge rakhte hain aur kuch alag nahi karte. Isliye resonance acid se zyada ion ko stabilise karta hai, aur yeh equilibrium 7.15 ko right ki taraf dhakelta hai.

SimulationEk atom par ek charge, ya ek charge share hua

Stage par fixed negative charges ke do groups hain. Left mein −1 ka ek akela charge alkoxide ion ke oxygen ko dikhata hai. Right mein chaar chhote charges, upar phenoxide oxygen ke liye −0.55 aur dono ortho carbons aur para carbon par −0.15 each, milkar wahi −1 banate hain. Field lines dono groups par converge hoti hain. Ek positive test charge, jo proton ko dikhata hai, kahin bhi drag kiya ja sakta hai, aur readout wala ek arrow us par lagne wala force dikhata hai.

Fig. 7.10Left: ek alkoxide, jiska poora −1 charge oxygen par hai. Right: ek phenoxide, jismein wahi −1 oxygen (−0.55) aur teen ring carbons mein share hota hai (illustrative shares). Positive test charge proton ka role karta hai.

Try karo

Proton ko drag karke left wale akele charge ke theek upar rakho, phir lagbhag utni hi doori par right wale top charge ke theek upar. Kaun sa pull zyada strong hai?
Proton ko dono groups se kaafi door le jao. Kya dono pulls ab bhi alag hain? Woh ek jaise kyun ho jaate hain?
Kaun sa ion proton ko zyada kaskar pakdega, aur isliye zyada strong base hoga? Isse matching acids ki strength ke baare mein kya pata chalta hai?

Ring par substituents. Table 7.7 ko upar se padho. Methyl group, jaise 4-methylphenol (ek cresol) mein, pKa ko thoda upar kar deta hai: electron-releasing groups us ring mein charge dhakelte hain jo pehle se negative charge utha rahi hai, isliye acid thoda weak ho jaata hai. Nitro group pKa ko neeche kheenchta hai, para position par lagbhag 3 units, lekin meta position par sirf lagbhag 1.6 units. Yeh farak resonance se aata hai. Jab $- N O_{2}$ ortho ya para carbon par ho, to anion ka ek resonance structure negative charge ko theek usi carbon par rakhta hai, aur woh nitro group ke electronegative oxygens par phail sakta hai. Meta position par resonance charge ko wahan kabhi nahi laata, isliye nitro group sirf σ bonds ke through madad karta hai (−I effect).

Table 7.725 °C par water mein acid strength (kam pKa = zyada strong acid)NCERT Table 7.3 · p. 207

Compound	pKa
ethanol	15.9
4-methylphenol	10.3
phenol	10.0
4-chlorophenol	9.4
3-nitrophenol	8.4
4-nitrophenol	7.2
2,4-dinitrophenol	4.1
2,4,6-trinitrophenol (picric acid)	0.4

InteractivePhenol acidity explorer

Buttons se phenol ring par substituent (none, methyl, methoxy, chloro, cyano ya nitro) aur uski position (ortho, meta ya para) chunte hain. 0 se 18 tak ka ek horizontal pKa scale chune gaye phenol ko ethanol, phenol aur carbonic acid ke saamne mark karta hai, aur ek line batati hai ki acid phenol se kitne guna strong ya weak hai aur kya woh sodium hydrogencarbonate se carbon dioxide nikalega. Phenoxide ion ki drawing mein substituent apni jagah dikhta hai; Step button negative charge ko oxygen se ortho, para aur doosre ortho carbons par le jaata hai, aur jab nitro ya cyano group ortho ya para par ho to ek extra structure us group par charge dikhata hai. Ek text line group ka effect samjhati hai.

Fig. 7.11Ek substituent aur ring position chuno, phir phenoxide ion ke resonance structures ek-ek karke dekho.

Example 7.4NCERT Example 7.4 · p. 207

Acid strength ki ranking

Acid strength ke badhte order mein arrange karo: 4-nitrophenol, ethanol, 4-chlorophenol, phenol, 2,4-dinitrophenol, 4-methylphenol.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

2. Esterification. –OH group ke hydrogen ko acyl group, $R C O^{-}$ , se badlo to ester milta hai. Acyl group carboxylic acid, acid chloride ya acid anhydride se aa sakta hai, aur alcohols aur phenols dono isme hissa lete hain. Yeh hai esterification (एस्टरीकरण).

\begin{aligned} R^{'} O H + R C O O H \\ \overset{H^{+}}{⇌} R C O O R^{'} + H_{2} O \end{aligned}

(7.16)

\begin{aligned} R^{'} O H + R C O C l \\ \overset{p y r i d i n e}{\to} R C O O R^{'} \\ + H C l \end{aligned}

(7.17)

Teeno reagents ko alag tarah se handle karna padta hai. Carboxylic acid dheere aur sirf aadha-adhoora react karta hai, isliye concentrated sulphuric acid ki kuch boondein use tez karti hain, aur bana hua water hata diya jaata hai (ya excess alcohol use hota hai) taaki equilibrium aage badhta rahe. Acid chloride aasaani se react karta hai lekin HCl chhodta hai; pyridine jaisa base HCl ko soak kar leta hai aur reaction ko poora karta hai. Phenols free carboxylic acids se bahut dheere react karte hain, isliye unhe acid chlorides ya anhydrides se esterify karte hain.

Jab acyl group acetyl, $C H_{3} C O^{-}$ , ho to reaction ko acetylation kehte hain. Aspirin, jo dard, bukhaar aur inflammation ki dawai hai, theek isi tarah banti hai: ethanoic anhydride salicylic acid (2-hydroxybenzoic acid) ke phenolic –OH ko acetylate karta hai.

(b) Alcohols mein C–O bond ke cleavage wale reactions

Yeh reactions alcohols ke hain. Phenol mein C–O bond mein partial double-bond character hota hai, aur ring carbon par peeche se attack nahi ho sakta, isliye phenols apne –OH ko halogen se nahi badalte. Phenol ka sirf ek C–O cleavage tumhe jaanna hai: zinc dust se reduction ((c) Phenols ke reactions).

1. Hydrogen halides ke saath. Alcohols HCl, HBr ya HI ke saath alkyl halides dete hain, jaisa tumne Unit 6 mein dekha. Protonation –OH ko ek achhe leaving group, water, mein badal deta hai. Tertiary alcohols sabse tez react karte hain, kyunki woh stable carbocations banate hain.

\begin{aligned} R - O H + H X \\ \overset{}{\to} R - X + H_{2} O \end{aligned}

(7.18)

Kyunki teeno classes HCl ke saath itni alag speed se react karti hain, yeh reaction ek test ka kaam bhi karta hai, Lucas test. Lucas reagent concentrated hydrochloric acid aur anhydrous zinc chloride hai. Trick solubility mein hai: chhota alcohol reagent mein ghul jaata hai lekin uska chloride nahi ghulta, isliye jaise hi chloride banta hai, saaf liquid milky (turbid) ho jaata hai. Ghadi dekho: tertiary alcohol turant dhundhla hota hai, secondary alcohol lagbhag paanch minute mein, aur primary alcohol room temperature par saaf rehta hai.

Try karke dekhoNCERT Lucas test · p. 208

Teen butanols ki race

Tumhe chahiye

Lucas reagent (teacher banayenge aur denge)
butan-1-ol, butan-2-ol aur 2-methylpropan-2-ol
stoppers wali teen sookhi test tubes
ek stopwatch

Pehle guess karo

Kaun si tube sabse pehle dhundhli hogi?

butan-1-olbutan-2-ol2-methylpropan-2-ol

Tumhare teacher teen labelled, sookhi test tubes mein se har ek mein 2 mL Lucas reagent daalenge.
Har tube mein ek alag butanol ki paanch boondein daalo, stopper lagao, ek baar hilao aur stopwatch shuru karo.
Tubes ko dark background ke saamne pakdo aur note karo ki har ek kab dhundhli hoti hai. Das minute baad ruk jao.

Table 7.8Observations

Alcohol	Time
Butan-1-ol
Butan-2-ol
2-Methylpropan-2-ol

Tumhari entries apne aap save hoti hain.

2. Phosphorus halides ke saath. Phosphorus tribromide alcohols ko alkyl bromides mein badalta hai, aur phosphorus trichloride, phosphorus pentachloride ya thionyl chloride alkyl chlorides dete hain.

\begin{aligned} 3 R - O H + P B r_{3} \\ \overset{}{\to} 3 R - B r \\ + H_{3} P O_{3} \end{aligned}

(7.19)

3. Dehydration. Alcohol se ek water molecule nikaal do to alkene bachta hai. Strong protic acids, concentrated sulphuric ya phosphoric acid, liquid mein yeh karte hain; alcohol vapour ke liye garam alumina ya anhydrous zinc chloride catalyst ka kaam karte hain. Yeh hai dehydration (निर्जलीकरण). Alcohol ki class tay karti hai ki kitna zor lagana padega. Ethanol ko lagbhag 443 K par concentrated sulphuric acid chahiye; secondary alcohols naram conditions mein water kho dete hain; tertiary alcohols ko sirf kaafi dilute acid aur 350 K se thoda upar temperature chahiye. Dehydration ki aasaani, tertiary > secondary > primary, involved carbocations ki stability ko follow karti hai.

\begin{aligned} C H_{3} C H_{2} O H \\ \to_{443 K}^{H_{2} S O_{4}} C H_{2} = C H_{2} \\ + H_{2} O \end{aligned}

(7.20)

Mechanism acid-catalysed hydration ka ulta hai (Fig. 7.12). Pehle –OH oxygen acid se ek proton leta hai; yeh fast aur reversible hai. Phir protonated alcohol ek water molecule chhod deta hai, aur carbocation bachta hai. Yeh step sabse slow hai, isliye yahi rate control karta hai. Aakhir mein ek base (water ya $H S O_{4}^{-}$ ) cation ke bagal wale carbon se proton kheench leta hai, aur C=C banta hai. Protons gino: ek shuru mein andar jaata hai aur ek aakhir mein bahar aata hai, isliye acid use nahi hota; woh catalyst hai. Kyunki har step ulta chal sakta hai, isliye alkene bante hi use distil karke hata dete hain.

2/4Water nikalta hai; carbocation banta hai (slow step).

Fig. 7.12Protonate karo, water nikaalo (slow), proton nikaalo: alkene banta hai aur acid wapas mil jaata hai.NCERT Mechanism · p. 209

Ek cyclohexane ring ke upar-right carbon par OH group hai. Step 1: OH oxygen ke lone pair se ek proton tak curved arrow, fast likha hai. Step 2: oxygen ab OH2 plus hai, aur ek curved arrow C–O bond ke electrons ko water ke saath nikalte dikhata hai, slow aur rate-determining likha hai. Step 3: ring carbon ab positive hai, aur ek water molecule agle carbon se hydrogen kheenchta hai jabki woh C–H bond double bond ban jaata hai. Step 4: product, cyclohexene, aur wapas mila acid catalyst, saath mein note ki alkene distil karke hata diya jaata hai.

Ethanol jaise primary alcohols ke liye textbooks yahi teen steps banati hain. Sach kahein to primary carbocation akele exist karne ke liye bahut unstable hai; primary alcohol mein steps 2 aur 3 saath-saath hote hain, jab water nikalte hi base β-hydrogen hata deta hai. Product same rehta hai.

Example

Dehydration se kaun sa alkene?

3-methylpentan-3-ol, $C H_{3} C H_{2} C (O H) (C H_{3}) C H_{2} C H_{3}$ , ko acid ke saath garam karne par main product predict karo.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

4. Oxidation. Oxidation mein alcohol do hydrogen atoms khota hai, ek oxygen wala aur ek uske bagal wale carbon ka, aur unki jagah C=O bond aa jaata hai; isliye chemists ise dehydrogenation bhi kehte hain. Yeh ho sakta hai ya nahi, aur kitna aage jaata hai, yeh is par depend karta hai ki –OH wale carbon par kitne hydrogens hain (Fig. 7.13).

1/4Primary: 2 H; secondary: 1 H; tertiary: koi nahi.

Fig. 7.13Carbinol carbon par H atoms ki ginti product tay karti hai.NCERT p. 209

Teen rows mein ek primary, ek secondary aur ek tertiary alcohol hai, har ek mein OH wala carbon apne chaar bonds ke saath bana hai. Step 1 us carbon ke hydrogens ko circle karta hai: primary ke do, secondary ka ek, tertiary ka koi nahi. Step 2 mein primary alcohol oxidise hokar aldehyde aur phir carboxylic acid banta hai, aur note hai ki PCC aldehyde par ruk jaata hai. Step 3 mein secondary alcohol oxidise hokar ketone banta hai, jo wahin ruk jaata hai. Step 4 note karta hai ki tertiary alcohol ke paas hatane ko koi hydrogen nahi, isliye C=O nahi banta.

Primary alcohols aldehydes dete hain, jo aasaani se aage oxidise hokar carboxylic acids ban jaate hain. Acidified potassium permanganate ya dichromate, dono strong oxidants, seedhe acid tak jaate hain. Aldehyde par rokna ho to milder reagent use karo: pyridinium chlorochromate (PCC, chromium trioxide, pyridine aur HCl se bana), ya anhydrous solvent mein $C r O_{3}$ .
Secondary alcohols ketones dete hain, jaise $C r O_{3}$ ya acidified dichromate ke saath. Ketone ke carbonyl carbon par koi hydrogen nahi hota, isliye woh aage oxidation ka virodh karta hai.
Tertiary alcohols ke –OH wale carbon par koi hydrogen nahi hota, isliye ordinary oxidising agents unhe chhod dete hain. Garam, concentrated permanganate se zabardasti karo to carbon skeleton hi toot jaata hai, aur chhote acids ka mixture bachta hai.

\begin{aligned} R C H_{2} O H \\ \overset{P C C}{\to} R C H O \\ ya \\ \to_{H^{+}}^{K M n O_{4}} R C O O H \end{aligned}

(7.21)

\begin{aligned} R_{2} C H O H \\ \overset{C r O_{3}}{\to} R_{2} C = O \end{aligned}

(7.22)

Garam copper par. 573 K par copper bina reagent wala tareeka deta hai. Alcohol vapour garam metal ke upar se guzarti hai aur hydrogen gas nikalti hai, aur aldehyde (1° alcohol se) ya ketone (2° alcohol se) bachta hai. Tertiary alcohol ke paas dene ko hydrogen nahi hai, isliye garam copper par woh uski jagah water kho deta hai aur alkene ban jaata hai.

\begin{aligned} (C H_{3})_{2} C H O H \to_{573 K}^{C u} \\ C H_{3} C O C H_{3} + H_{2} \\ (C H_{3})_{3} C O H \to_{573 K}^{C u} \\ (C H_{3})_{2} C = C H_{2} \\ + H_{2} O \end{aligned}

(7.23)

(c) Phenols ke reactions

–OH group phenol ki ring ko electrophiles ke liye benzene se kahin zyada reactive bana deta hai. Oxygen ka ek lone pair ring mein delocalise hota hai, usi resonance se jaise phenoxide ion mein (Fig. 7.9), isliye ortho aur para carbons electron-rich ho jaate hain. Isliye –OH group ek activating, ortho/para-directing group hai, aur neeche ke reactions inhi positions par hote hain.

1. Nitration. Phenol itna reactive hai ki sirf dilute nitric acid, lagbhag 298 K par, use nitrate kar deta hai; benzene ko concentrated nitric aur sulphuric acids ka garam mixture chahiye. Product 2-nitrophenol aur 4-nitrophenol ka mixture hai, jise steam distillation alag karta hai: 2-nitrophenol steam ke saath chala jaata hai aur 4-nitrophenol peeche reh jaata hai. 2-nitrophenol mein O–H hydrogen theek bagal wale nitro group ke ek oxygen se, usi molecule ke andar (intramolecular), bond karta hai, isliye molecules na ek doosre se zyada chipakte hain na water se. 4-nitrophenol mein dono groups bahut door hain, isliye hydrogen bonds alag-alag molecules ko jodte hain (intermolecular) aur unhe peeche rokte hain (Fig. 7.14).

\begin{aligned} C_{6} H_{5} O H \to_{298 K}^{d i l \cdot H N O_{3}} \\ H O C_{6} H_{4} N O_{2} \\ (2- aur 4-isomers) \end{aligned}

(7.24)

Fig. 7.14Ek molecule ke andar ka hydrogen bond (left) neighbours ko jodne ke liye kuch nahi chhodta; molecules ke beech wala (right) unhe saath pakde rakhta hai.NCERT p. 211

Left mein 2-nitrophenol: OH group aur nitro group bagal-bagal ke ring carbons par hain, aur ek dotted line OH hydrogen ko ek nitro oxygen se jodti hai, jisse molecule ke andar six-membered ring band ho jaati hai. Right mein 4-nitrophenol: OH group aur nitro group ring ke aamne-saamne sides par hain, aur dotted lines iske OH hydrogen ko ek padosi molecule ke nitro group se aur iske nitro oxygen ko doosre ke OH se jodti hain, jisse alag molecules jud jaate hain.

Teen nitro groups tak jaana zyada mushkil hai. Akela concentrated nitric acid kaafi phenol ko oxidise kar deta hai, isliye 2,4,6-trinitrophenol (picric acid) ki yield kam aati hai. Pehle sulphonation ring ko protect karta hai: concentrated sulphuric acid se phenol-2,4-disulphonic acid milta hai, aur phir concentrated nitric acid dono $- S O_{3} H$ groups ko nitro groups se badal deta hai aur ek teesra bhi jod deta hai. Picric acid ek strong acid hai (pKa 0.4), kyunki teen nitro groups uske anion se charge kheench lete hain.

2. Halogenation. Benzene ko bromine polarise karne ke liye $F e B r_{3}$ jaisa Lewis acid chahiye; phenol ki activated ring yeh polarising khud kar leti hai. Bromination kitna aage jaata hai, yeh solvent par depend karta hai. Carbon disulphide ya chloroform mein 273 K par, jahan phenol un-ionised rehta hai, ek bromine andar aata hai, zyaadatar –OH ke para par. Water mein kuch phenol ionise hokar kahin zyada reactive phenoxide ion banata hai, aur teeno ortho aur para positions ek saath brominate ho jaati hain: 2,4,6-tribromophenol white solid ki tarah alag ho jaata hai. Bromine ka colour gayab hona aur white precipitate aana phenol ka ek quick test hai.

\begin{aligned} C_{6} H_{5} O H + B r_{2} \\ \to_{273 K}^{C S_{2}} B r C_{6} H_{4} O H \\ + H B r \\ (zyaadatar para) \end{aligned}

(7.25)

\begin{aligned} C_{6} H_{5} O H + 3 B r_{2} \overset{H_{2} O}{\to} \\ C_{6} H_{2} B r_{3} O H ↓ \\ + 3 H B r \end{aligned}

(7.26)

Try karke dekho

Phenol ke do quick tests

Tumhe chahiye

dilute (lagbhag 1 %) phenol solution, teacher handle karenge
ethanol
neutral iron(III) chloride solution
bromine water
chaar test tubes

Pehle guess karo

Neutral iron(III) chloride ke saath kaun sa liquid violet ho jaayega?

ethanoldonophenol solutionkoi nahi

Tumhare teacher do tubes mein 2 mL dilute phenol solution aur do aur tubes mein 2 mL ethanol daalenge.
Ek phenol tube aur ek ethanol tube mein neutral iron(III) chloride solution ki do boondein daalo. Colour note karo.
Baaki do tubes mein hilate hue boond-boond karke bromine water daalo. Colour aur koi solid ho to note karo.

Table 7.9Observations

Tube	Tumhe kya dikhta hai
Phenol + iron(III) chloride
Ethanol + iron(III) chloride
Phenol + bromine water
Ethanol + bromine water

Tumhari entries apne aap save hoti hain.

Example 7.5NCERT Example 7.5 · p. 212

Naye groups kahan jaate hain?

Har reaction ka major product batao.

4-methylphenol ka mononitration.
3-methylphenol ke saath excess bromine water.
4-methoxyphenol ka mononitration.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

3. Kolbe's reaction. Carbon dioxide itna kamzor electrophile hai ki benzene, ya phenol par bhi, attack nahi kar sakta. Phenoxide ion, jiska poora negative charge ring ko mil raha hai, kaafi reactive hai. Sookhe sodium phenoxide ko $C O_{2}$ ke saath lagbhag 400 K aur 4–7 atm par garam karo, to oxygen ke bagal mein ring par ek carboxylate group jud jaata hai; acidify karo, to 2-hydroxybenzoic acid (salicylic acid) milta hai, jo aspirin ka starting material hai. Yeh hai Kolbe reaction.

\begin{aligned} C_{6} H_{5} O N a + C O_{2} \\ \to_{4 - 7 a t m}^{400 K} \\ C_{6} H_{4} (O H) C O O N a \\ \overset{H^{+}}{\to} C_{6} H_{4} (O H) C O O H \end{aligned}

(7.27)

4. Reimer–Tiemann reaction. Chloroform aur aqueous alkali ek alag one-carbon electrophile dete hain. Base $C H C l_{3}$ se HCl nikaal kar dichlorocarbene, $: C C l_{2}$ , banata hai, jo oxygen ke bagal mein phenoxide ring par attack karta hai. Jo $- C H C l_{2}$ group banta hai (jisse intermediate ek substituted benzal chloride ban jaata hai), use wahi alkali hydrolyse karke –CHO bana deta hai, aur acid work-up se 2-hydroxybenzaldehyde (salicylaldehyde) milta hai. Yeh hai Reimer–Tiemann reaction.

\begin{aligned} C_{6} H_{5} O H \to_{N a O H}^{C H C l_{3}} \\ C_{6} H_{4} (O^{-}) C H C l_{2} \\ \overset{O H^{-}}{\to} \overset{H^{+}}{\to} \\ C_{6} H_{4} (O H) C H O \end{aligned}

(7.28)

5. Zinc dust se reduction. Zinc dust ke saath garam karne par phenol apna oxygen kho deta hai aur benzene deta hai, jabki zinc, zinc oxide ban jaata hai. Yahan yahi ek reaction hai jismein phenol ka C–O bond tootta hai.

\begin{aligned} C_{6} H_{5} O H + Z n \\ \overset{h e a t}{\to} C_{6} H_{6} + Z n O \end{aligned}

(7.29)

6. Oxidation. Phenol ki ring aasaani se oxidise hoti hai. Chromic acid (acidified dichromate) use 1,4-benzoquinone mein badal deta hai, jo ek yellow compound hai jismein do C=O groups conjugation mein hain. Air bhi dheere-dheere yeh kar deta hai: mahino tak rakhi phenol ki bottle quinone-type products jama hone se pehle pink aur phir brown ho jaati hai.

\begin{aligned} C_{6} H_{5} O H \\ \to_{H_{2} S O_{4}}^{N a_{2} C r_{2} O_{7}} O = C_{6} H_{4} = O \end{aligned}

(7.30)

Practice · 4 questions

Practice: alcohols aur phenols ke reactions: answers ke saath

1
Short answerMediumNCERT Intext Question 7.6
Har alcohol ka (i) HCl aur $Z n C l_{2}$ , (ii) HBr, (iii) $S O C l_{2}$ ke saath main organic product batao.
1. Pentan-1-ol
  Solution dikhao
  (i) 1-chloropentane (dheere, garam karne par); (ii) 1-bromopentane; (iii) 1-chloropentane, saath mein $S O_{2}$ aur HCl gases.
2. 1-Methylcyclopentan-1-ol
  Solution dikhao
  (i) 1-chloro-1-methylcyclopentane (turant: tertiary alcohol hai); (ii) 1-bromo-1-methylcyclopentane; (iii) 1-chloro-1-methylcyclopentane.
2
Short answerMediumNCERT Intext Question 7.7
Har alcohol ko concentrated phosphoric acid ke saath garam karne par banne wala major alkene predict karo.
1. 2-Methylbutan-2-ol
  2-methylbut-2-ene2-methylbut-1-ene3-methylbut-1-ene
  Answer dekho
  Answer (A) 2-methylbut-2-ene
  C2 par tertiary cation C3 se H khota hai, aur trisubstituted alkene $(C H_{3})_{2} C = C H C H_{3}$ milta hai.
2. Pentan-2-ol
  pent-1-enepentan-2-onepent-2-ene
  Answer dekho
  Answer (C) pent-2-ene
  C3 se H nikalne par disubstituted pent-2-ene milta hai, jo pent-1-ene se zyada stable hai. Ketone ke liye oxidising agent chahiye hota.
Long answerHardNCERT Intext Question 7.8
Anions ke resonance structures use karke samjhao ki 4-nitrophenol (pKa 7.2) 3-nitrophenol (pKa 8.4) se kaafi zyada strong acid kyun hai.
Solution dikhao
Phenoxide ion mein negative charge oxygen aur C2, C4 aur C6 par dikhta hai.
4-nitrophenoxide mein ek structure charge ko C4 par rakhta hai, yaani $- N O_{2}$ wale carbon par. Phir charge nitro oxygens par chala jaata hai, aur aisa structure banta hai jismein C=N hai aur do O atoms charge share karte hain. In electronegative atoms par delocalise hone se anion bahut stable ho jaata hai.
3-nitrophenoxide mein charge kabhi C3 tak nahi pahunchta, isliye nitro group sirf σ bonds ke through electrons kheench sakta hai (−I). Anion kam stable hota hai, aur acid weak hota hai, phir bhi phenol (pKa 10.0) se strong.
4
Short answerMediumNCERT Intext Question 7.9
Woh reactions likho jo 4-methylphenol ko (a) 2-hydroxy-5-methylbenzoic acid aur (b) 2-hydroxy-5-methylbenzaldehyde mein badalte hain. Har reaction ka naam batao.
1. 2-Hydroxy-5-methylbenzoic acid
  Solution dikhao
  Kolbe reaction: NaOH se sodium 4-methylphenoxide milta hai; $C O_{2}$ ke saath lagbhag 400 K aur 4–7 atm par garam karo; acidify karo. –COOH, –OH ke ortho par aata hai, jo acid group ke relative C5 hai.
2. 2-Hydroxy-5-methylbenzaldehyde
  Solution dikhao
  Reimer–Tiemann reaction: $C H C l_{3}$ aur aqueous NaOH ke saath garam karo, phir acidify karo. –CHO, –OH ke ortho par aata hai.

InteractiveReaction bench: alcohols aur phenol

Chaar buttons compound chunte hain: ethanol (primary), propan-2-ol (secondary), 2-methylpropan-2-ol (tertiary) ya phenol. Nau buttons reagent chunte hain: sodium metal, aqueous sodium hydroxide, Lucas reagent, PCC, acidified dichromate, 573 K par garam copper, heat ke saath concentrated sulphuric acid, bromine water aur neutral iron(III) chloride. Add dabane par ek test tube dikhti hai jiske contents zaroorat ke hisaab se colour badalte hain, dhundhle hote hain, bubbles dete hain ya precipitate banate hain, saath mein product ka formula aur naam aur result samjhane wala ek sentence. Jo reagents phenol ke saath use nahi hote, woh yeh bata dete hain.

Fig. 7.15Ek compound aur ek reagent chuno, phir Add dabao aur dekho ki kya product banta hai aur tumhe kya dikhega.

7.5 Kuch Commercially Important Alcohols

Do alcohols bahut bade scale par bante hain: methanol aur ethanol.

Methanol

Purana naam wood spirit yaad dilata hai ki methanol, $C H_{3} O H$ , pehle kahan se aata tha: band bartan mein lakdi garam karne par nikalne wala liquid (destructive distillation). Aaj ke plants ise synthesis gas se banate hain, carbon monoxide aur hydrogen ko high pressure aur temperature par catalyst ke upar milakar. Original process kuch sau atmospheres par zinc oxide–chromium(III) oxide catalyst use karta tha; naye copper–zinc oxide catalysts kam pressure par kaam karte hain.

\begin{aligned} C O + 2 H_{2} \\ \to_{h i g h P, T}^{Z n O - C r_{2} O_{3}} C H_{3} O H \end{aligned}

(7.31)

Methanol (b.p. 338 K) dikhne aur smell mein kaafi had tak ethanol jaisa hai, aur yahi use khatarnaak banata hai: kuch millilitres nigalne se insaan andha ho sakta hai, aur thoda zyada maar sakta hai (methanol zeher kyun hai). Iska sabse bada single use methanal (formaldehyde) ke raw material ki tarah hai; yeh paints aur varnishes mein solvent ki tarah, aur badhte taur par fuel ki tarah bhi use hota hai.

Ethanol

Yeast hazaaron saalon se sugars ke fermentation (किण्वन) se insaanon ke liye ethanol, $C_{2} H_{5} O H$ , bana raha hai. India mein zyaadatar fermentation ethanol molasses se aata hai, woh dark syrup jo ganne ke ras se sugar crystallise karne ke baad bachta hai. Do enzymes chemistry karte hain: invertase sucrose ko glucose aur fructose mein todta hai, aur yeast ka zymase dono ko ethanol aur carbon dioxide mein badalta hai (Fig. 7.16).

\begin{aligned} C_{12} H_{22} O_{11} + H_{2} O \\ \overset{i n v e r t a s e}{\to} \\ C_{6} H_{12} O_{6} + C_{6} H_{12} O_{6} \\ (glucose + fructose) \end{aligned}

(7.32)

\begin{aligned} C_{6} H_{12} O_{6} \overset{z y m a s e}{\to} \\ 2 C_{2} H_{5} O H + 2 C O_{2} ↑ \end{aligned}

(7.33)

3/4Zymase sugars ko ethanol mein badalta hai; $C O_{2}$ bubbles bankar nikal jaati hai.

Fig. 7.16Do enzymes, koi air nahi: sucrose → glucose aur fructose → ethanol aur carbon dioxide.NCERT p. 214

Beech mein bina air ka ek band vessel hai. Step 1: usmein molasses ka sucrose hai, aur yeast daala jaata hai. Step 2: enzyme invertase ne sucrose ko glucose aur fructose, C6H12O6, mein tod diya hai. Step 3: yeast ka enzyme zymase sugars ko ethanol mein badalta hai, aur carbon dioxide ke bubbles upar uthkar bahar nikalte hain. Step 4: lagbhag 14 per cent ethanol par yeast kaam karna band kar deta hai; ek side note warn karta hai ki agar air andar aaye to ethanol oxidise hokar ethanoic acid ban jaata hai.

Do limits process ko shape dete hain. Yeast sugar ko sirf bina air ke (anaerobic conditions) ferment karta hai, isliye fermenters seal kiye jaate hain aur carbon dioxide ek valve se nikalti hai. Aur yeast apna hi product bardaasht nahi kar sakta: lagbhag 14 % ethanol par zymase kaam karna band kar deta hai, isliye isse strong kuch bhi distil karna padta hai. Air andar aane do to doosre microbes kabza kar lete hain aur ethanol ko oxidise karke ethanoic acid bana dete hain; isi tarah jaan-boojh kar vinegar banaya jaata hai, aur laaparwaahi se rakha drink kharaab hota hai.

Industry ke liye ethanol ko jaan-boojh kar kharaab kiya jaata hai taaki koi use piye nahi. Is denaturation mein thoda copper sulphate milate hain, jo use neela rang deta hai, aur pyridine, jo use badboodaar bana deta hai. Fermentation ke alawa industry ethene ko hydrate karke bhi ethanol banati hai (Alkenes se). 351 K boiling point aur polar aur non-polar dono substances ko ghol sakne ki taakat ke saath, ethanol paints, medicines aur sanitisers ke liye ek mehnati solvent hai, ek fuel hai, aur kai doosre carbon compounds ka starting material hai.

7.6 Ethers

O–H bond na hone se ethers alcohols se kaafi kam reactive hote hain. Isi se woh useful solvents bante hain: diethyl ether fats, oils aur kai organic compounds ko unse react kiye bina ghol deta hai.

7.6.1 Ethers ka Preparation

1. Alcohols ka dehydration. Ethanol ko concentrated sulphuric acid ke saath 443 K tak garam karo to ethene nikalti hai ((b) Alcohols mein C–O bond ke cleavage wale reactions). Mixture ko thanda rakho, lagbhag 413 K par, aur ethanol excess mein ho, to uski jagah do ethanol molecules ek oxygen ke through jud jaate hain: product ethoxyethane (diethyl ether) hai.

\begin{aligned} 2 C_{2} H_{5} O H \to_{413 K}^{H_{2} S O_{4}} \\ C_{2} H_{5} O C_{2} H_{5} + H_{2} O \end{aligned}

(7.34)

Ether ek SN2 reaction se banta hai. Ek ethanol molecule protonate hota hai. Doosra ethanol molecule, nucleophile ki tarah, pehle wale ke $C H_{2}$ carbon par peeche se attack karta hai aur water ko bahar dhakel deta hai. Phir ek proton nikalne se ether milta hai. Equations mein R ethyl group, $C_{2} H_{5}$ , ke liye hai.

\begin{aligned} R O H + H^{+} \\ \overset{}{⇌} R O H_{2}^{+} \\ R O H + R O H_{2}^{+} \\ \overset{}{\to} R - O^{+} (H) - R \\ + H_{2} O \\ R - O^{+} (H) - R \\ \overset{}{\to} R - O - R + H^{+} \end{aligned}

(7.35)

Teen conditions poori honi chahiye. SN2 step ko attack ke liye ek khula, primary carbon chahiye. Temperature kam rehna chahiye, kyunki heat elimination ko favour karti hai. Aur ether ke dono hisse same alcohol se aane chahiye. Secondary aur tertiary alcohols pehla test fail karte hain: acid mein woh carbocations banate hain, jo doosra alcohol molecule lene se kahin tezi se proton chhodkar alkenes de dete hain. Do alag alcohols aakhri test fail karte hain: ethanol aur propan-1-ol ko acid mein garam karne par diethyl, dipropyl aur ethyl propyl ethers saath mein bante hain, jinhe phir alag karna padta hai.

2. Williamson synthesis. Laboratory mein do groups ko ek oxygen se jodne ka bharosemand tareeka hai C–O bond ko SN2 se banana: alcohol aur sodium se bana alkoxide ion ek alkyl halide par attack karta hai aur halide ion ko bahar dhakel deta hai. Yeh symmetrical aur unsymmetrical, dono tarah ke ethers ke liye kaam karta hai. Yeh hai Williamson synthesis.

\begin{aligned} R - X + R^{'} - O^{-} N a^{+} \\ \overset{}{\to} R - O - R^{'} + N a X \end{aligned}

(7.36)

Is reaction ka har rule usi SN2 step se nikalta hai. Jis carbon par attack ho, woh khula hona chahiye: methyl ya primary. Alkoxide ek strong base bhi hai, isliye crowded secondary halide ether aur alkene ka mixture deta hai, aur tertiary halide lagbhag sirf alkene deta hai. Isliye planning rule: tertiary ya koi aur bulky group hamesha alkoxide bankar aana chahiye, kabhi halide bankar nahi (Fig. 7.17).

3/3Methoxide 3° halide se β-H kheench leta hai: alkene banta hai.

Fig. 7.17Bulky group alkoxide par rakho aur chhota group halide par.NCERT p. 216

Target ether, tert-butyl methyl ether (CH3)3C–O–CH3, upar bana hai. Step 1 iske do C–O bonds mark karta hai, methyl side par a aur tert-butyl side par b. Step 2 route a dikhata hai: sodium tert-butoxide aur bromomethane khule methyl carbon par SN2 se ether dete hain, tick laga hai. Step 3 route b jodta hai: sodium methoxide aur 2-bromo-2-methylpropane uski jagah 2-methylpropene dete hain, kyunki methoxide base ki tarah kaam karke β-hydrogen hata deta hai; koi ether nahi banta, cross laga hai.

Phenols bhi isi tarah alkyl aryl ethers dete hain. Sodium hydroxide phenol ko sodium phenoxide mein badalta hai, jo phir primary alkyl halide par attack karta hai. Ulta pair fail hota hai: alkoxide ordinary aryl halide ke $s p^{2}$ carbon par peeche se attack nahi kar sakta, isliye koi ether nahi banta.

\begin{aligned} C_{6} H_{5} O H \overset{N a O H}{\to} \\ C_{6} H_{5} O^{-} N a^{+} \\ \overset{C H_{3} I}{\to} C_{6} H_{5} O C H_{3} \\ + N a I \end{aligned}

(7.37)

Example 7.6NCERT Example 7.6 · p. 216

Sahi Williamson pair chunna

Ek student petrol additive 2-methoxy-2-methylbutane, $(C H_{3})_{2} C (O C H_{3}) C H_{2} C H_{3}$ , banane ke liye sodium methoxide ko 2-chloro-2-methylbutane ke saath garam karta hai.

Main product kya hai?
Reactants ka ek behtar pair suggest karo.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

7.6.2 Physical Properties

Ether molecule bent hota hai, isliye uske do polar C–O bonds use ek chhota dipole moment dete hain. Chhota hi asli baat hai. Table 7.10 dikhata hai ki 1-ethoxypropane hexane se kuch hi kelvin ke andar boil karta hai, jabki same mass wala pentan-1-ol lagbhag 70 K upar boil karta hai. Alcohol ke molecules hydrogen bonds se bandhe hote hain; ether, jismein O–H hydrogen nahi hai, apne molecules ke beech yeh nahi bana sakta.

Table 7.10Milte-julte mass ka ek alkane, ek ether aur ek alcohol

Compound (molar mass)	Boiling point
hexane (86 g/mol)	342 K
1-ethoxypropane (88 g/mol)	lagbhag 337 K
pentan-1-ol (88 g/mol)	411 K

Water ke saath picture badal jaati hai. Ether oxygen par ab bhi lone pairs hain, isliye woh water molecule se hydrogen bond le sakta hai. Isliye ethers milte-julte size ke hydrocarbons se kahin behtar ghulte hain, aur ether aam taur par milte-julte mass ke alcohol jitna hi soluble hota hai. Ek zabardast example tetrahydrofuran hai, ek oxygen wali five-membered ring, jo water mein kisi bhi proportion mein mix ho jaati hai, jabki cyclopentane, wahi ring jismein oxygen ki jagah $C H_{2}$ hai, lagbhag bilkul nahi ghulta.

7.6.3 Chemical Reactions

Jalne ke alawa ethers room temperature par bahut kam kuch karte hain, isiliye chemists solvents ki tarah un par bharosa karte hain. Yahan do reactions important hain.

1. C–O bond ka cleavage. Garam concentrated HI ya HBr ether ko ek alcohol aur ek alkyl halide mein tod deta hai; excess acid ke saath alcohol aage doosra alkyl halide ban jaata hai. Reactivity ka order HI > HBr > HCl hai, kyunki HI sabse strong acid hai aur iodide sabse achha nucleophile; HCl mushkil se kaam karta hai.

\begin{aligned} R - O - R + H X \\ \overset{}{\to} R - X + R - O H \\ excess HX: \\ R - O H + H X \\ \overset{}{\to} R - X + H_{2} O \end{aligned}

(7.38)

Mechanism (Fig. 7.18) ether oxygen ke protonation se shuru hota hai, jo alkoxy group ko ek neutral alcohol mein badal deta hai jo nikal sakta hai. Phir halide ion attack karta hai. Agar dono groups primary ya secondary hon, to iodide kam hindered carbon par SN2 se attack karta hai, isliye chhota group alkyl iodide banta hai. Agar ek group tertiary ho, to uska C–O bond pehle tootta hai (SN1), kyunki isse stable tertiary carbocation milta hai; phir tertiary group iodide ban jaata hai.

2/4 $I^{-}$ methyl carbon par attack karta hai, jo kam crowded side hai.

Fig. 7.18Pehle protonate karo; phir chhote group par SN2, ya ek group tertiary ho to SN1. Aryl–O bond bacha rehta hai.NCERT Mechanism · p. 218

Step 1: 2-methoxypropane aur HI se protonated ether aur ek iodide ion milte hain. Step 2: iodide methyl carbon par attack karta hai, jo kam crowded side hai, aur iodomethane aur propan-2-ol milte hain. Step 3: tert-butyl methyl ether mein protonated ether methanol aur tert-butyl carbocation mein tootta hai, jo phir iodide lekar 2-iodo-2-methylpropane deta hai. Step 4: protonated methoxybenzene se phenol aur iodomethane milte hain; ring–oxygen bond kabhi nahi tootta.

Alkyl aryl ethers hamesha alkyl–oxygen bond par toot-te hain aur phenol aur alkyl halide dete hain. Aryl–oxygen bond zyada strong hai, ismein kuch double-bond character hai, aur ring carbon SN2 nahi kar sakta. Isi wajah se phenol aage aryl halide nahi banta, excess HI ke saath bhi nahi.

\begin{aligned} C_{6} H_{5} O C H_{3} + H I \\ \overset{}{\to} C_{6} H_{5} O H + C H_{3} I \end{aligned}

(7.39)

Example 7.7NCERT Example 7.7 · p. 219

HI kaun sa bond todta hai?

Har ether ko HI ke ek equivalent ke saath garam karne par main products batao.

$C H_{3} C H_{2} O C H_{2} C H (C H_{3})_{2}$
$(C H_{3})_{2} C (O C_{2} H_{5}) C H_{2} C H_{3}$
4-methylmethoxybenzene, $p$ - $C H_{3} C_{6} H_{4} O C H_{3}$

Pehle khud try karo. Phir solution ek-ek step karke kholo.

2. Aryl alkyl ethers mein electrophilic substitution. –OH ki tarah alkoxy group bhi ring ko ek lone pair deta hai. Yeh ring ko activate karta hai aur aane wale groups ko ortho aur para positions par bhejta hai; aam taur par para product zyada banta hai kyunki alkoxy group ortho positions ko crowd karta hai.

Halogenation. Ethanoic acid mein ghula bromine methoxybenzene (anisole) ko bina kisi Lewis-acid catalyst ke brominate kar deta hai; lagbhag poora product 4-bromoanisole hota hai.
Friedel–Crafts reactions. Alkyl halides aur acyl chlorides bhi attack karte hain, anhydrous $A l C l_{3}$ catalyst ke saath, aur phir se para product zyada banta hai: chloroethane se zyaadatar 4-ethylanisole milta hai, aur propanoyl chloride se zyaadatar 1-(4-methoxyphenyl)propan-1-one.
Nitration. Concentrated nitric aur sulphuric acids ka mixture 2- aur 4-nitroanisole deta hai, zyaadatar 4-isomer.

\begin{aligned} C_{6} H_{5} O C H_{3} + B r_{2} \\ \overset{C H_{3} C O O H}{\to} \\ B r C_{6} H_{4} O C H_{3} \\ + H B r \end{aligned}

(7.40)

\begin{aligned} C_{6} H_{5} O C H_{3} \\ + C_{2} H_{5} C O C l \overset{A l C l_{3}}{\to} \\ C_{2} H_{5} C O C_{6} H_{4} O C H_{3} \\ + H C l \end{aligned}

(7.41)

\begin{aligned} C_{6} H_{5} O C H_{3} \to_{H_{2} S O_{4}}^{H N O_{3}} \\ O_{2} N C_{6} H_{4} O C H_{3} \\ + H_{2} O \end{aligned}

(7.42)

Practice · 3 questions

Practice: ethers: answers ke saath

Short answerMediumNCERT Intext Question 7.10
Dikhao ki 2-methoxy-4-methylpentane, $C H_{3} C H (O C H_{3})$ – $C H_{2} C H (C H_{3})_{2}$ , ko methanol aur 4-methylpentan-2-ol se shuru karke Williamson synthesis se kaise banaya ja sakta hai.
Solution dikhao
Methanol ko HBr (ya $P B r_{3}$ ) se methyl halide mein badlo: $C H_{3} O H + H B r$ → $C H_{3} B r + H_{2} O$ .
4-methylpentan-2-ol mein sodium metal daalo: hydrogen nikalti hai aur sodium alkoxide banta hai.
Alkoxide ka bromomethane par SN2 ether aur NaBr deta hai. Uski jagah sodium methoxide aur 2-bromo-4-methylpentane use karne par elimination se zyaadatar alkene milta.
Quick answerMediumNCERT Intext Question 7.11
1-ethoxy-4-methylbenzene banane ke liye kaun sa pair behtar choice hai, aur kyun?
4-bromotoluene + $C_{2} H_{5} O N a$ 4-methylphenol + ethanol, acid ke saathsodium 4-methylphenoxide + $C_{2} H_{5} B r$
Answer dekho
Answer (C) sodium 4-methylphenoxide + $C_{2} H_{5} B r$
Phenoxide bromoethane ke primary carbon par SN2 se attack karta hai. Alkoxide 4-bromotoluene ke $s p^{2}$ carbon par attack nahi kar sakta, aur acid dehydration se aryl ethers nahi bante.
3
Short answerMediumNCERT Intext Question 7.12
Products predict karo.
1. $C H_{3} O C H_{2} C H_{2} C H_{2} C H_{3}$ + HBr
  Solution dikhao
  Bromomethane + butan-1-ol (methyl carbon par SN2).
2. $C_{6} H_{5} O C H_{3}$ + HBr
  Solution dikhao
  Phenol + bromomethane.
3. $C_{6} H_{5} O C_{2} H_{5}$ + $C_{2} H_{5} C l$ , $A l C l_{3}$
  Solution dikhao
  Zyaadatar 1-ethoxy-4-ethylbenzene, saath mein thoda 2-isomer: ethoxy group naye ethyl group ko para par bhejta hai.
4. $(C H_{3})_{3} C O C H_{3}$ + HI
  Solution dikhao
  2-Iodo-2-methylpropane + methanol (tertiary carbocation ke through SN1).

Recap

Summary aur key points

Alcohols ( $R - O H$ ), phenols ( $A r - O H$ ) aur ethers ( $R - O - R^{'}$ ) ko –OH groups ki ginti se, –OH wale carbon se (1°, 2°, 3°, allylic, benzylic, vinylic) aur, ethers ke liye, dono groups same hain ya nahi isse classify karte hain (Section 7.1).
IUPAC names: alkane -e → -ol, –OH ko sabse chhota locant; diols mein -e rehta hai; ethers bade group ke alkoxy derivatives hain (Section 7.2).
Oxygen $s p^{3}$ hai: alcohols mein lone pairs angle ko 109.5° se neeche band karte hain, ethers mein bulky groups use lagbhag 112° tak kholte hain, aur phenol ka C–O bond chhota (136 pm) hai (Section 7.3).
Alcohols alkenes se (acid hydration, Markovnikov; hydroboration–oxidation, anti-Markovnikov), aldehydes, ketones, acids aur esters ke reduction se, aur Grignard reagents se methanal (1°), baaki aldehydes (2°) ya ketones (3°) ke saath bante hain (Section 7.4.1).
Phenol chlorobenzene, benzenesulphonic acid, benzenediazonium salts ya, zyaadatar, cumene se banta hai (Section 7.4.2).
Hydrogen bonding alcohols aur phenols ko high boiling points aur water solubility deti hai; boiling points chain length ke saath badhte hain aur branching se girte hain (Section 7.4.3).
Phenol (pKa 10) alcohols (pKa lagbhag 16) se kaafi zyada strong acid hai kyunki phenoxide ka charge delocalised hai; ortho/para electron-withdrawing groups use strong banate hain, alkyl groups weak ((a) O–H bond ke cleavage wale reactions).
Alcohols esters banate hain, HX ke saath alkyl halides dete hain (Lucas test: 3° fast, 1° slow), dehydrate hokar alkenes bante hain (3° > 2° > 1°), aur oxidise hote hain: 1° → aldehyde → acid, 2° → ketone, 3° virodh karte hain ((b) Alcohols mein C–O bond ke cleavage wale reactions).
–OH group phenol ki ring ko ortho/para substitution ke liye activate karta hai: nitration, bromination, Kolbe (→ salicylic acid) aur Reimer–Tiemann (→ salicylaldehyde) ((c) Phenols ke reactions).
Methanol CO aur $H_{2}$ se banta hai aur bahut toxic hai; ethanol sugars ke fermentation aur ethene se banta hai (Section 7.5).
Ethers primary alcohols ke 413 K par acid dehydration se ya Williamson synthesis (alkoxide + primary halide) se bante hain (Section 7.6.1).
Ethers alkanes ki tarah boil karte hain lekin alcohols ki tarah ghulte hain; HI unhe chhote group par SN2 se ya tertiary group par SN1 se todta hai, aur alkoxy groups ortho/para direct karte hain (Section 7.6.3).

Flash cards · 8

Named reactions aur tests

1 / 8

Practice · 36 questions

Practice questions answers ke saath (NCERT “Exercises”)

1
Short answerMediumNCERT Exercises Q7.1
Har compound ka IUPAC name likho.
1. $(C H_{3})_{2} C H$ – $C H (O H) C H_{2} C H_{3}$
  Solution dikhao
  2-Methylpentan-3-ol: kisi bhi end se –OH C3 par hai, aur phir methyl group ko 4 ki jagah 2 milta hai.
2. $H O C H_{2} C H_{2}$ – $C H (O H) C H_{3}$
  Solution dikhao
  Butane-1,3-diol: locants {1,3}, {2,4} se behtar hain.
3. $(C H_{3})_{3} C C H_{2} C H_{2} O H$
  Solution dikhao
  3,3-Dimethylbutan-1-ol.
4. $o$ - $C_{2} H_{5} C_{6} H_{4} O H$
  Solution dikhao
  2-Ethylphenol.
5. ek phenol jiske dono meta positions par $C H_{3}$ groups hain
  Solution dikhao
  3,5-Dimethylphenol.
6. thymol: C1 par –OH, C2 par isopropyl, C5 par methyl
  Solution dikhao
  5-Methyl-2-(propan-2-yl)phenol, jise 2-isopropyl-5-methylphenol bhi likhte hain: locants {2,5}, {3,6} se behtar hain.
7. $C H_{3} O (C H_{2})_{4} C H_{3}$
  Solution dikhao
  1-Methoxypentane.
8. $C_{6} H_{5} O C H_{2} C H_{2} C H_{3}$
  Solution dikhao
  Propoxybenzene.
2
Short answerMediumNCERT Exercises Q7.2
Har compound ki structure likho.
1. 3-Methylpentan-3-ol
  Solution dikhao
  $C H_{3} C H_{2}$ – $C (O H) (C H_{3})$ – $C H_{2} C H_{3}$
2. 2-Phenylethan-1-ol
  Solution dikhao
  $C_{6} H_{5} C H_{2} C H_{2} O H$
3. 2-Methylbutane-1,4-diol
  Solution dikhao
  $H O C H_{2} C H (C H_{3})$ – $C H_{2} C H_{2} O H$
4. 2,4-Dichlorophenol
  Solution dikhao
  Ek phenol ring jismein Cl, C2 (–OH ke bagal mein) aur C4 (–OH ke saamne) par hai.
5. 1-Methoxybutane
  Solution dikhao
  $C H_{3} O (C H_{2})_{3} C H_{3}$
6. 3-Ethoxy-2-methylhexane
  Solution dikhao
  $(C H_{3})_{2} C H$ – $C H (O C_{2} H_{5})$ – $C H_{2} C H_{2} C H_{3}$
7. 2-Cyclohexylpropan-2-ol
  Solution dikhao
  $C_{6} H_{11} C (C H_{3})_{2} O H$ : C–OH carbon par ek cyclohexane ring, jis carbon par do methyl groups bhi hain.
8. Cyclohex-2-en-1-ol
  Solution dikhao
  Ek cyclohexene ring jismein –OH C1 par hai aur double bond C2 aur C3 ke beech hai.
Long answerMediumNCERT Exercises Q7.3
Saat compounds ka formula $C_{4} H_{10} O$ hai. Sabko banao aur naam do, aur alcohols ko 1°, 2° ya 3° mein classify karo.
Solution dikhao
Alcohols: butan-1-ol, $C H_{3} (C H_{2})_{3} O H$ (1°); butan-2-ol, $C H_{3} C H_{2} C H (O H) C H_{3}$ (2°); 2-methylpropan-1-ol, $(C H_{3})_{2} C H C H_{2} O H$ (1°); 2-methylpropan-2-ol, $(C H_{3})_{3} C O H$ (3°).
Ethers: 1-methoxypropane, $C H_{3} O C H_{2} C H_{2} C H_{3}$ ; 2-methoxypropane, $C H_{3} O C H (C H_{3})_{2}$ ; ethoxyethane, $C_{2} H_{5} O C_{2} H_{5}$ .
Short answerEasyNCERT Exercises Q7.4
Butan-1-ol ( $M = 74$ ) 391 K par boil karta hai lekin pentane ( $M = 72$ ) 309 K par. Samjhao.
Solution dikhao
Masses, aur isliye dispersion forces, milte-julte hain. Butan-1-ol ke molecules ek molecule ke O–H hydrogen aur agle ke oxygen ke beech hydrogen bonds se bhi jude rehte hain, aur liquid ko boil karne ke liye inhe todna padta hai. Pentane mein sirf dispersion forces hain.
Short answerEasyNCERT Exercises Q7.5
Methanol water mein har proportion mein mix ho jaata hai, lekin 100 mL water mein sirf lagbhag 0.6 g hexan-1-ol ghulta hai. Samjhao.
Solution dikhao
Dono mein ek –OH group hai jo water ke saath hydrogen bond banata hai. Methanol mein yeh ek chhote se $C H_{3}$ group par haavi hai. Hexan-1-ol mein lambi $C_{6} H_{13}$ chain hydrogen bond nahi bana sakti aur water ke hydrogen-bonded network ko bigaad degi, isliye bahut kam ghulta hai.
Short answerMediumNCERT Exercises Q7.6
1-methylcyclohexene se hydroboration–oxidation kaun sa product deta hai, aur woh acid-catalysed hydration ke product se kaise alag hai?
Solution dikhao
Hydroboration–oxidation: boron C2 (C=C ka CH) par add hota hai aur –OH se replace hota hai, jisse 2-methylcyclohexan-1-ol milta hai (anti-Markovnikov).
Acid hydration: $H^{+}$ C2 par add hota hai, tertiary cation C1 par banta hai, aur water wahin add hota hai, jisse 1-methylcyclohexan-1-ol milta hai (Markovnikov).
Short answerHardNCERT Exercises Q7.7
$C_{8} H_{10} O$ formula wale kitne monohydric phenols hain? Unki list banao.
Solution dikhao
Ethylphenols: 2-, 3- aur 4-ethylphenol (3).
Dimethylphenols: 2,3-, 2,4-, 2,5-, 2,6-, 3,4- aur 3,5-dimethylphenol (6). Total 9.
Short answerMediumNCERT Exercises Q7.8
2-Hydroxybenzaldehyde steam ke saath distil hota hai; 4-hydroxybenzaldehyde nahi. Samjhao.
Solution dikhao
2-isomer mein O–H hydrogen usi molecule ke andar bagal wale C=O oxygen se hydrogen bond banata hai, isliye molecules ek doosre aur water ki taraf sirf weakly attract hote hain, aur compound volatile hai. 4-isomer mein groups door-door hain, isliye hydrogen bonds alag molecules ko jodte hain aur compound kaafi kam volatile hai.
Short answerMediumNCERT Exercises Q7.9
Benzene aur propene se shuru karke cumene route se phenol banane ke steps likho. Doosre product ka naam batao.
Solution dikhao
Benzene + propene acid catalyst ( $H_{3} P O_{4}$ ya $A l C l_{3}$ ) ke saath cumene, $C_{6} H_{5} C H (C H_{3})_{2}$ , dete hain.
Air cumene ko oxidise karke cumene hydroperoxide, $C_{6} H_{5} C (C H_{3})_{2} O O H$ , banati hai.
Dilute acid hydroperoxide ko phenol aur propanone (acetone) mein todta hai; propanone doosra product hai.
Short answerEasyNCERT Exercises Q7.10
Chlorobenzene se phenol banane ke reactions conditions ke saath likho, aur samjhao ki aakhri step mein acid kyun chahiye.
Solution dikhao
Chlorobenzene NaOH ke saath lagbhag 623 K aur high pressure par sodium phenoxide, $C_{6} H_{5} O^{-} N a^{+}$ , deta hai.
Alkali mein phenol phenoxide salt ki form mein rehta hai kyunki acid ke roop mein woh water se strong hai. HCl jaisa strong acid daalne par phenoxide protonate hota hai aur phenol free ho jaata hai.
Long answerMediumNCERT Exercises Q7.11
Step by step dikhao ki acid ki maujoodgi mein propene aur water propan-2-ol kaise dete hain, aur samjhao ki propan-1-ol main product kyun nahi hai.
Solution dikhao
Step 1: $H_{3} O^{+}$ propene ke $C H_{2}$ end ko ek proton deta hai. Isse secondary carbocation $(C H_{3})_{2} C H^{+}$ aur water bante hain.
Step 2: ek water molecule positive carbon se bond karta hai, aur oxonium ion $(C H_{3})_{2} C H O H_{2}^{+}$ milta hai.
Step 3: ek aur water molecule proton hata deta hai, aur propan-2-ol aur $H_{3} O^{+}$ milte hain.
Proton ko beech wale carbon par add karne se primary carbocation banta, jo kaafi kam stable hai, isliye –OH C2 par aata hai.
Short answerMediumNCERT Exercises Q7.12
Tumhare paas toluene, concentrated sulphuric acid, sodium hydroxide aur dilute hydrochloric acid hain. 4-methylphenol banane ke steps likho.
Solution dikhao
Toluene ko concentrated $H_{2} S O_{4}$ se sulphonate karo, zyaadatar 4-methylbenzenesulphonic acid milega.
Ise high temperature par solid NaOH ke saath fuse karo, sodium 4-methylphenoxide milega.
Dilute HCl se acidify karo taaki 4-methylphenol free ho jaaye.
13
Short answerMediumNCERT Exercises Q7.13
Dikhao ki tum har alcohol kaise banaoge.
1. Alkene se 2-Phenylpropan-2-ol
  Solution dikhao
  2-Phenylpropene, $C_{6} H_{5} C (C H_{3}) = C H_{2}$ , water aur dilute acid ke saath: $H^{+}$ $C H_{2}$ end par add hota hai aur benzylic tertiary cation water le leta hai, jisse $C_{6} H_{5} C (C H_{3})_{2} O H$ milta hai.
2. Alkyl halide se SN2 dwara 2-Cyclohexylethan-1-ol
  Solution dikhao
  (2-Bromoethyl)cyclohexane, $C_{6} H_{11} C H_{2} C H_{2} B r$ , ko aqueous NaOH ke saath garam karo: hydroxide primary carbon par bromide ko replace karta hai.
3. Alkyl halide se 3-Methylbutan-1-ol
  Solution dikhao
  1-Bromo-3-methylbutane aqueous NaOH ya KOH ke saath.
Short answerMediumNCERT Exercises Q7.14
Do experiments batao jo dikhate hain ki phenol ek acid hai, aur ek jo dikhata hai ki woh carbonic acid se weak hai. Phenol ethanol se lagbhag kitne guna zyada strong acid hai?
Solution dikhao
Phenol sodium ke saath hydrogen deta hai: $2 C_{6} H_{5} O H + 2 N a$ → $2 C_{6} H_{5} O N a + H_{2}$ .
Yeh aqueous NaOH mein ghul jaata hai: $C_{6} H_{5} O H + N a O H$ → $C_{6} H_{5} O N a + H_{2} O$ .
Phenol sodium hydrogencarbonate solution se $C O_{2}$ nahi nikaalta, isliye woh carbonic acid (pKa 6.4) se weak hai.
Ethanol aqueous NaOH se react nahi karta. Phenol (pKa 10) lagbhag $10^{6}$ guna zyada strong hai, kyunki phenoxide ka charge ring par delocalised hai.
Short answerMediumNCERT Exercises Q7.15
Samjhao ki 4-cyanophenol (pKa 7.9) 4-methoxyphenol (pKa 10.2) se zyada strong acid kyun hai.
Solution dikhao
4-cyanophenoxide mein negative charge C4 tak pahunchta hai aur –C≡N group ke nitrogen par phail sakta hai, jo electronegative hai; anion stable hota hai aur acid zyada strong hota hai.
Methoxy group ring mein ek lone pair deta hai (+R), jo wahin electron density badhata hai jahan phenoxide ka charge pehle se hai, aur anion ko destabilise karta hai. 4-Methoxyphenol to phenol se bhi thoda weak hai.
Short answerMediumNCERT Exercises Q7.16
Bromine water bina catalyst ke phenol ko turant brominate kar deta hai, lekin benzene ko liquid bromine aur $F e B r_{3}$ chahiye. Samjhao, aur batao ki bromine atoms kahan jaate hain.
Solution dikhao
–OH ke oxygen ka ek lone pair ring mein delocalise hota hai, isliye resonance structures C2, C4 aur C6 par negative charge rakhte hain. Ring benzene se kahin zyada electron-rich hai aur bina catalyst ke $B r_{2}$ ko polarise kar deti hai.
Electrophile electron-rich ortho aur para carbons par attack karta hai, isliye water mein teeno positions (2, 4 aur 6) brominate ho jaati hain.
17
Short answerMediumNCERT Exercises Q7.17
Har reaction ka main organic product likho.
1. Butan-1-ol ko excess acidified potassium dichromate ke saath reflux mein garam kiya
  Solution dikhao
  Butanoic acid, $C H_{3} C H_{2} C H_{2} C O O H$ .
2. 4-Methylphenol 273 K par $C S_{2}$ mein $B r_{2}$ ke saath
  Solution dikhao
  2-Bromo-4-methylphenol: para position blocked hai, isliye bromine –OH ke ortho par jaata hai.
3. 2-Methylphenol dilute nitric acid ke saath
  Solution dikhao
  2-Methyl-4-nitrophenol aur 2-methyl-6-nitrophenol (–OH ke para aur ortho par).
4. Phenol ko zinc dust ke saath garam kiya
  Solution dikhao
  Benzene (aur zinc oxide).
18
Long answerMediumNCERT Exercises Q7.18
Har ek ko example ke saath samjhao.
1. Kolbe reaction
  Solution dikhao
  Sodium 2-methylphenoxide ko $C O_{2}$ ke saath lagbhag 400 K aur 4–7 atm par garam karke, phir acidify karne par 2-hydroxy-3-methylbenzoic acid milta hai: –COOH, –OH ke ortho wali khaali position par aata hai.
2. Reimer–Tiemann reaction
  Solution dikhao
  Phenol ko chloroform aur aqueous NaOH ke saath garam karne par ortho dichloromethyl intermediate banta hai, jise alkali hydrolyse karta hai; acidify karne par 2-hydroxybenzaldehyde milta hai.
3. Williamson synthesis
  Solution dikhao
  Sodium propoxide bromoethane ke saath SN2 se 1-ethoxypropane aur NaBr deta hai.
4. Unsymmetrical ether
  Solution dikhao
  Aisa ether jiske oxygen par do alag groups hon, jaise methoxybenzene, $C_{6} H_{5} O C H_{3}$ , ya 2-methoxypropane.
Long answerMediumNCERT Exercises Q7.19
Propan-2-ol ko concentrated sulphuric acid ke saath garam karne par propene milta hai. Teen steps mein mechanism banao aur slow step mark karo.
Solution dikhao
Step 1 (fast): $(C H_{3})_{2} C H O H + H^{+}$ ⇌ $(C H_{3})_{2} C H O H_{2}^{+}$ .
Step 2 (slow): protonated alcohol water khokar secondary carbocation $(C H_{3})_{2} C H^{+}$ deta hai.
Step 3: ek base methyl group se proton hata deta hai, jisse $C H_{3} C H = C H_{2}$ milta hai aur $H^{+}$ wapas mil jaata hai.
20
Short answerMediumNCERT Exercises Q7.20
Tum har conversion kaise karoge?
1. But-1-ene → butan-1-ol
  Solution dikhao
  Hydroboration–oxidation: $B H_{3}$ ( $B_{2} H_{6}$ se), phir $H_{2} O_{2}$ aur NaOH.
2. 4-Methylbenzyl chloride → (4-methylphenyl)methanol
  Solution dikhao
  Aqueous NaOH ke saath garam karo (benzylic carbon par SN2).
3. Methylmagnesium bromide → ethanol
  Solution dikhao
  Methanal daalo, phir water ya dilute acid: $C H_{3} M g B r + H C H O$ se $C H_{3} C H_{2} O M g B r$ milta hai, jo hydrolyse hokar $C H_{3} C H_{2} O H$ banta hai.
4. Ethylmagnesium bromide → 3-methylpentan-3-ol
  Solution dikhao
  Butanone, $C H_{3} C O C H_{2} C H_{3}$ , daalo, phir water: ethyl group carbonyl carbon se bond karta hai, jis par aakhir mein $C H_{3}$ , do ethyl groups aur –OH hote hain.
21
Short answerEasyNCERT Exercises Q7.21
Har change ke liye ek reagent ka naam batao.
1. Propan-2-ol → propanone
  Solution dikhao
  $C r O_{3}$ , PCC ya acidified dichromate.
2. Ethanol → ethanal (wahin rukna hai)
  Solution dikhao
  Pyridinium chlorochromate (PCC).
3. Phenol → 4-bromophenol
  Solution dikhao
  273 K par $C S_{2}$ (ya $C H C l_{3}$ ) mein bromine.
4. Ethanol → ethanoic acid
  Solution dikhao
  Acidified potassium dichromate ya permanganate.
5. Butan-2-ol → but-2-ene
  Solution dikhao
  Concentrated sulphuric ya phosphoric acid, garam karke.
6. Propanal → propan-1-ol
  Solution dikhao
  $N a B H_{4}$ , $L i A l H_{4}$ ya Ni par $H_{2}$ .
Short answerEasyNCERT Exercises Q7.22
Propan-1-ol aur methoxyethane ka molar mass same (60 g/mol) hai, lekin woh 370 K aur 281 K par boil karte hain. Samjhao.
Solution dikhao
Propan-1-ol ke molecules apne O–H groups ke through aapas mein hydrogen bond banate hain, jinhe todne mein extra energy lagti hai. Methoxyethane mein O–H hydrogen nahi hai, isliye sirf weak dipole aur dispersion forces uske molecules ko saath rakhti hain.
23
Short answerMediumNCERT Exercises Q7.23
Har ether ka IUPAC name batao.
1. $C H_{3} O C H_{2} C H_{2} C H_{2} C l$
  Solution dikhao
  1-Chloro-3-methoxypropane (prefixes alphabetical order mein).
2. $p$ - $C H_{3} C_{6} H_{4} O C H_{3}$
  Solution dikhao
  1-Methoxy-4-methylbenzene.
3. $(C H_{3} C H_{2} C H_{2})_{2} O$
  Solution dikhao
  1-Propoxypropane.
4. $C_{6} H_{5} O C H_{2} C_{6} H_{5}$
  Solution dikhao
  (Benzyloxy)benzene; iska common name benzyl phenyl ether hai.
5. $C_{2} H_{5} O C_{5} H_{9}$ (ek cyclopentane ring)
  Solution dikhao
  Ethoxycyclopentane.
6. $(C H_{3})_{3} C O C_{2} H_{5}$
  Solution dikhao
  2-Ethoxy-2-methylpropane.
24
Short answerMediumNCERT Exercises Q7.24
Har ether ke Williamson synthesis ke liye reagents batao.
1. 1-Butoxybutane
  Solution dikhao
  Sodium butoxide + 1-bromobutane.
2. Methoxybenzene
  Solution dikhao
  Sodium phenoxide + iodomethane (bromobenzene + methoxide nahi).
3. 2-Ethoxy-2-methylbutane
  Solution dikhao
  Sodium 2-methylbutan-2-oxide + bromoethane.
4. 1-Methoxypropane
  Solution dikhao
  Sodium methoxide + 1-bromopropane, ya sodium propoxide + bromomethane: dono halides unhindered hain.
Short answerHardNCERT Exercises Q7.25
Ek student ne Williamson synthesis se di-tert-butyl ether aur diphenyl ether banane ki koshish ki. Samjhao ki dono koshishein fail kyun hoti hain.
Solution dikhao
Di-tert-butyl ether ko kisi bhi tarah todo, tertiary halide chahiye. tert-Butoxide ek strong base hai, isliye woh 2-bromo-2-methylpropane se β-hydrogen hata deta hai aur 2-methylpropene deta hai.
Diphenyl ether ke liye phenoxide ko aryl halide par attack karna hoga, lekin $s p^{2}$ ring carbon par SN2 se peeche se attack nahi ho sakta, isliye Williamson conditions mein koi ether nahi banta.
Long answerMediumNCERT Exercises Q7.26
Dibutyl ether (1-butoxybutane) sirf butan-1-ol se banaya ja sakta hai. Conditions batao aur mechanism dikhao.
Solution dikhao
Butan-1-ol ko concentrated $H_{2} S O_{4}$ ke saath moderate temperature par garam karo, alcohol excess mein ho.
Step 1: $C_{4} H_{9} O H + H^{+}$ ⇌ $C_{4} H_{9} O H_{2}^{+}$ .
Step 2 (SN2): butan-1-ol ka doosra molecule $O H_{2}^{+}$ ke bagal wale $C H_{2}$ par attack karta hai, water ko hatakar $C_{4} H_{9} O^{+} (H) C_{4} H_{9}$ deta hai.
Step 3: $H^{+}$ nikalne se $C_{4} H_{9} O C_{4} H_{9}$ milta hai.
Short answerMediumNCERT Exercises Q7.27
2-methylpropan-2-ol ko concentrated sulphuric acid ke saath garam karne par 2-methylpropene milta hai, di-tert-butyl ether nahi. Kyun?
Solution dikhao
Protonated tertiary alcohol turant water khokar stable tertiary carbocation banata hai. Cation β-hydrogen itni tezi se khota hai ki bulky doosra alcohol molecule us tak pahunch hi nahi paata, isliye elimination jeetta hai. SN2 ether route ko unhindered primary carbon chahiye.
28
Short answerMediumNCERT Exercises Q7.28
Har ether ke garam concentrated HI ke saath products likho.
1. 1-Butoxybutane excess HI ke saath
  Solution dikhao
  1-iodobutane ke do molecules (aur water).
2. Ethoxybenzene
  Solution dikhao
  Phenol + iodoethane.
3. 2-Methoxy-2-methylpropane
  Solution dikhao
  2-Iodo-2-methylpropane + methanol.
Short answerMediumNCERT Exercises Q7.29
Samjhao ki ethoxybenzene ka nitration benzene ke nitration se tez kyun hota hai aur zyaadatar ortho aur para products kyun deta hai.
Solution dikhao
Ether oxygen ka ek lone pair ring mein delocalise hota hai, jisse C2, C4 aur C6 par extra electron density aati hai. Ring electrophile $N O_{2}^{+}$ ko benzene se tez attract karti hai, aur in carbons par attack se aise intermediates bante hain jinmein oxygen positive charge share kar sakta hai. Para product zyada banta hai kyunki ethoxy group ortho positions ko crowd karta hai.
Long answerMediumNCERT Exercises Q7.30
Methoxyethane ko HI ke ek equivalent ke saath garam kiya jaata hai. Mechanism ka har step dikhao aur tay karo ki kaun sa alkyl iodide banta hai.
Solution dikhao
Step 1: $C H_{3} O C H_{2} C H_{3} + H I$ ⇌ $C H_{3} O^{+} (H)$ – $C H_{2} C H_{3}$ + $I^{-}$ .
Step 2 (SN2): $I^{-}$ methyl carbon par attack karta hai, jo ethyl $C H_{2}$ se kam hindered hai, aur $C H_{3} I$ aur ethanol milte hain.
Excess HI ke saath ethanol aage iodoethane mein badal jaata hai.
31
Short answerMediumNCERT Exercises Q7.31
Ethoxybenzene ke har reaction ka main product likho.
1. Chloromethane, anhydrous $A l C l_{3}$
  Solution dikhao
  1-Ethoxy-4-methylbenzene (saath mein thoda 2-isomer).
2. Concentrated nitric aur sulphuric acids
  Solution dikhao
  1-Ethoxy-4-nitrobenzene (saath mein thoda 2-isomer).
3. Ethanoic acid mein bromine
  Solution dikhao
  1-Bromo-4-ethoxybenzene.
4. Ethanoyl chloride, anhydrous $A l C l_{3}$
  Solution dikhao
  1-(4-Ethoxyphenyl)ethan-1-one.
32
Short answerHardNCERT Exercises Q7.32
Har alcohol banane ke liye tum kaun sa alkene aur kaun sa method use karoge?
1. 2-Methylpentan-2-ol
  Solution dikhao
  2-Methylpent-1-ene (ya 2-methylpent-2-ene) water aur dilute acid ke saath.
2. 1-Ethylcyclopentan-1-ol
  Solution dikhao
  1-Ethylcyclopentene water aur dilute acid ke saath.
3. 2-Methylpropan-1-ol
  Solution dikhao
  2-Methylpropene, hydroboration–oxidation se.
4. Cyclohexylmethanol
  Solution dikhao
  Methylenecyclohexane, $C_{6} H_{10} = C H_{2}$ , hydroboration–oxidation se.
Long answerHardNCERT Exercises Q7.33
2-Methylpentan-3-ol HBr se react karta hai, lekin product 2-bromo-2-methylpentane hai: bromine C3 par nahi, C2 par aata hai. Mechanism se samjhao.
Solution dikhao
Step 1: C3 par laga –OH ek proton leta hai aur $- O H_{2}^{+}$ ban jaata hai, jo achha leaving group hai.
Step 2: water nikalta hai, aur C3 par secondary carbocation banta hai.
Step 3: C2 ka ek hydrogen apne bonding pair ke saath C3 par shift hota hai (1,2-hydride shift). Positive charge ab C2 par hai, jis par do methyl groups hain: ek zyada stable tertiary carbocation.
Step 4: $B r^{-}$ C2 se bond karta hai, aur $(C H_{3})_{2} C B r C H_{2} C H_{2} C H_{3}$ , 2-bromo-2-methylpentane, milta hai.
Quick answerEasy
Kaun sa reagent phenol aur cyclohexanol mein farak batata hai?
sodium metalneutral iron(III) chlorideconcentrated HClwater
Answer dekho
Answer (B) neutral iron(III) chloride
Dono compounds sodium ke saath hydrogen dete hain; sirf phenol neutral iron(III) chloride ke saath violet colour deta hai.
35
Quick answerEasy
Acid ke saath dehydration ki badhti aasaani ke order mein arrange karo.
1. 2-methylpropan-2-ol
2. butan-1-ol
3. butan-2-ol
Answer dekho
Answer
butan-1-ol
butan-2-ol
2-methylpropan-2-ol
Carbocation jitni aasaani se bane (3° > 2° > 1°), dehydration utna aasaan.
Quick answerMedium
Picric acid, 2,4,6-trinitrophenol, sodium hydrogencarbonate solution se $C O_{2}$ nikaalta hai; phenol nahi nikaalta.
SahiGalat
Answer dekho
Answer Sahi
Picric acid (pKa 0.4) carbonic acid (pKa 6.4) se kahin zyada strong hai; phenol (pKa 10) weak hai.

Apna NCERT exercise question dhoondo

Hamare practice questions ncert.ai ke liye likhe gaye hain aur NCERT exercises ko follow karte hain. Apni textbook ke question se match karne wala question dhoondo; uska answer uske saath hai.

Tumhari NCERT textbook mein	Yahan practice question
NCERT Intext Question 7.1	Practice: alcohols ko classify karna · Q1
NCERT Intext Question 7.2	Practice: alcohols ko classify karna · Q2
NCERT Intext Question 7.3	Practice: naamkaran · Q1
NCERT Intext Question 7.4	Practice: alcohols banana · Q1
NCERT Intext Question 7.5	Practice: alcohols banana · Q2
NCERT Intext Question 7.6	Practice: alcohols aur phenols ke reactions · Q1
NCERT Intext Question 7.7	Practice: alcohols aur phenols ke reactions · Q2
NCERT Intext Question 7.8	Practice: alcohols aur phenols ke reactions · Q3
NCERT Intext Question 7.9	Practice: alcohols aur phenols ke reactions · Q4
NCERT Intext Question 7.10	Practice: ethers · Q1
NCERT Intext Question 7.11	Practice: ethers · Q2
NCERT Intext Question 7.12	Practice: ethers · Q3
NCERT Exercises Q7.1	Exercises · Q1
NCERT Exercises Q7.2	Exercises · Q2
NCERT Exercises Q7.3	Exercises · Q3
NCERT Exercises Q7.4	Exercises · Q4
NCERT Exercises Q7.5	Exercises · Q5
NCERT Exercises Q7.6	Exercises · Q6
NCERT Exercises Q7.7	Exercises · Q7
NCERT Exercises Q7.8	Exercises · Q8
NCERT Exercises Q7.9	Exercises · Q9
NCERT Exercises Q7.10	Exercises · Q10
NCERT Exercises Q7.11	Exercises · Q11
NCERT Exercises Q7.12	Exercises · Q12
NCERT Exercises Q7.13	Exercises · Q13
NCERT Exercises Q7.14	Exercises · Q14
NCERT Exercises Q7.15	Exercises · Q15
NCERT Exercises Q7.16	Exercises · Q16
NCERT Exercises Q7.17	Exercises · Q17
NCERT Exercises Q7.18	Exercises · Q18
NCERT Exercises Q7.19	Exercises · Q19
NCERT Exercises Q7.20	Exercises · Q20
NCERT Exercises Q7.21	Exercises · Q21
NCERT Exercises Q7.22	Exercises · Q22
NCERT Exercises Q7.23	Exercises · Q23
NCERT Exercises Q7.24	Exercises · Q24
NCERT Exercises Q7.25	Exercises · Q25
NCERT Exercises Q7.26	Exercises · Q26
NCERT Exercises Q7.27	Exercises · Q27
NCERT Exercises Q7.28	Exercises · Q28
NCERT Exercises Q7.29	Exercises · Q29
NCERT Exercises Q7.30	Exercises · Q30
NCERT Exercises Q7.31	Exercises · Q31
NCERT Exercises Q7.32	Exercises · Q32
NCERT Exercises Q7.33	Exercises · Q33

Quick check: MCQs

7.1.3 Ethers3 questions
Ethers ka naamkaran4 questions
7.3 Functional Groups ki Structures3 questions
7.4.2 Phenols ka Preparation4 questions
7.4.3 Physical Properties4 questions
(a) O–H bond ke cleavage wale reactions5 questions
(b) Alcohols mein C–O bond ke cleavage wale reactions4 questions
(c) Phenols ke reactions4 questions
Ethanol4 questions
7.6.3 Chemical Reactions4 questions

Glossary · 15

Key terms (English + Hindi)

alcoholऐल्कोहॉलaelkohol: Aisa compound jismein –OH group ek $s p^{3}$ carbon se bonded ho, $R - O H$ .Chapter mein pehli baar yahan aaya →

dehydrationनिर्जलीकरणnirjaleekaran: Ek water molecule ko hatana, jaise alcohol se alkene ya ether banane mein.Chapter mein pehli baar yahan aaya →
denaturation of alcohol: Copper sulphate aur pyridine jaise substances milakar ethanol ko peene layak na rehne dena.Chapter mein pehli baar yahan aaya →

esterificationएस्टरीकरणesteereekaran: Alcohol ya phenol aur carboxylic acid, acid chloride ya anhydride se ester banana.Chapter mein pehli baar yahan aaya →
etherईथरeethar: Aisa compound jismein ek oxygen atom do carbon groups se bonded ho, $R - O - R^{'}$ .Chapter mein pehli baar yahan aaya →

fermentationकिण्वनkinvan: Yeast jaise microbes ke enzymes se bina air ke sugars ka tootna, jisse ethanol aur carbon dioxide milte hain.Chapter mein pehli baar yahan aaya →

hydroboration–oxidation: Alkene mein $B H_{3}$ , phir $H_{2} O_{2}$ aur NaOH daalna, jisse aisa alcohol mile jiska –OH kam substituted carbon par ho.Chapter mein pehli baar yahan aaya →
hydrogen bondहाइड्रोजन आबंधhaaidrojan aabandh: O, N ya F se bonded hydrogen aur aise hi kisi doosre atom ke lone pair ke beech ka attraction.Chapter mein pehli baar yahan aaya →

Kolbe reaction: Sodium phenoxide aur pressure mein $C O_{2}$ , phir acid, jisse 2-hydroxybenzoic (salicylic) acid milta hai.Chapter mein pehli baar yahan aaya →

Lucas test: Conc. HCl aur $Z n C l_{2}$ : 3° alcohol ise turant dhundhla karta hai, 2° alcohol minutes mein, 1° alcohol room temperature par nahi.Chapter mein pehli baar yahan aaya →

phenolफ़ीनॉलpheenol: Aisa compound jismein –OH group seedha aromatic ring ke carbon se bonded ho, $A r - O H$ ; sabse simple wala bhi, $C_{6} H_{5} O H$ .Chapter mein pehli baar yahan aaya →
phenoxide ion: Phenol ke proton khone par bacha anion $C_{6} H_{5} O^{-}$ ; iska charge oxygen aur teen ring carbons par phaila hota hai.Chapter mein pehli baar yahan aaya →

Reimer–Tiemann reaction: Phenol aur $C H C l_{3}$ aur aqueous NaOH, phir acid, jisse 2-hydroxybenzaldehyde milta hai.Chapter mein pehli baar yahan aaya →

symmetrical ether: Aisa ether jiske oxygen par dono groups same hon; alag hon to ether unsymmetrical (mixed) hai.Chapter mein pehli baar yahan aaya →

Williamson synthesis: Sodium alkoxide ya phenoxide aur primary alkyl halide ke SN2 reaction se ether banana.Chapter mein pehli baar yahan aaya →

Alcohols, Phenols and Ethers: Class 12 Chemistry Chapter 7 Hinglish mein

Is chapter mein aap kya seekhenge

7.1 Classification

7.1.1 Alcohols — Mono, Di, Tri ya Polyhydric alcohols

7.1.2 Phenols — Mono, Di aur trihydric phenols

7.1.3 Ethers

Practice: alcohols ko classify karna: answers ke saath

7.2 Nomenclature

Alcohols ka naamkaran

Phenols ka naamkaran

Ethers ka naamkaran

Practice: naamkaran: answers ke saath

7.3 Functional Groups ki Structures

7.4 Alcohols aur Phenols

7.4.1 Alcohols ka Preparation

Alkenes se

Carbonyl compounds se

Grignard reagents se

7.4.2 Phenols ka Preparation

Practice: alcohols banana: answers ke saath

7.4.3 Physical Properties

7.4.4 Chemical Reactions

(a) O–H bond ke cleavage wale reactions

(b) Alcohols mein C–O bond ke cleavage wale reactions

(c) Phenols ke reactions

Practice: alcohols aur phenols ke reactions: answers ke saath

7.5 Kuch Commercially Important Alcohols

Methanol

Ethanol

7.6 Ethers

7.6.1 Ethers ka Preparation

7.6.2 Physical Properties

7.6.3 Chemical Reactions

Practice: ethers: answers ke saath

Summary aur key points

Practice questions answers ke saath (NCERT “Exercises”)

Apna NCERT exercise question dhoondo

Quick check: MCQs

Key terms (English + Hindi)

Tum chapter ke end tak pahunch gaye