Aldehydes, Ketones and Carboxylic Acids: Class 12 Chemistry Chapter 8 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
29 practice questions
45 MCQs

Is chapter mein aap kya seekhenge

Aldehydes, ketones aur carboxylic acids ke naam common aur IUPAC rules se rakho, aur naam se unke structures banao
Carbonyl aur carboxyl groups ka flat, polar structure samjhao aur usse predict karo ki reagents kahan attack karte hain
Alcohols, hydrocarbons, acid derivatives, nitriles aur Grignard reagents se aldehydes, ketones aur carboxylic acids banane ke liye sahi reagents aur named reactions chuno
Carbonyl compounds aur acids ke boiling points aur solubility ko dipole–dipole forces aur hydrogen bonding se jodo
Carbonyl group par nucleophilic addition aur addition–elimination samjhao, aur aldehydes aur ketones ko reactivity ke hisaab se rank karo
Reduction, oxidation, haloform, aldol aur Cannizzaro reactions ke products predict karo, aur simple tests se carbonyl compounds ko alag pehchano
Carboxylic acids ki acidity samjhao, inductive, resonance aur hybridisation effects se acids ko rank karo, aur carboxyl group ke reactions predict karo
Aldehydes, ketones aur carboxylic acids ke common uses batao

NCERT Chemistry Class 12, Chapter 8, pp. 227–258 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Nail-polish remover ki bottle kholo, to jo tez smell aati hai woh propanone (acetone) hai. Thoda ghee garam karo, to uski rich, buttery khushboo ka ek hissa butane-2,3-dione se aata hai. Masala chai mein daali lemongrass ki lemony khushboo citral ki wajah se hai, aur achaar ke jar mein vinegar ka khattapan ethanoic acid se hai. Yeh chaaron molecules ek hi chhoti unit ke around bane hain: ek carbon atom jo ek oxygen atom se double bond se juda hai, yaani carbonyl group, $> C = O$ .

Unit 7 mein humne aise compounds padhe jinmein C–O single bond hota hai: alcohols, phenols aur ethers. C=O double bond bilkul alag tarah behave karta hai. Yeh flat hai, strongly polar hai aur attack ke liye khula hai. Isi wajah se carbonyl compounds organic synthesis aur living cells ki chemistry ke centre mein hain (sugars aldehydes aur ketones hain, fats esters hain). Solvents, plastics, perfumes aur medicines banane wali industries bhi inhi par depend karti hain.

Carbonyl carbon se aur kya juda hai, yahi family decide karta hai (Fig. 8.1). Aldehyde mein wahan kam se kam ek hydrogen hota hai, ketone mein do carbon groups hote hain, aur carboxylic acid mein ek hydroxyl group hota hai. Us –OH ko kisi aur group se replace karo to acid derivatives milte hain: acyl chlorides (–Cl), esters (–OR′), amides (–NH₂) aur acid anhydrides (–OCOR′).

3/7Ek –OH group: carboxylic acid, RCOOH.

Fig. 8.1C=O group same rehta hai; dashed slot wala group family decide karta hai.NCERT p. 227

Ek carbonyl group bana hai jismein O upar aur C neeche hai, aur lower left par ek R group hai; lower right wala slot highlight kiya gaya hai, aur right side par saat general formulas ki list neeche tak jaati hai. Step 1 slot mein H rakhta hai aur family ka naam aldehyde, RCHO batata hai. Step 2 slot mein R′ rakhta hai: ketone, RCOR′. Step 3 OH rakhta hai: carboxylic acid, RCOOH. Steps 4 se 7 slot mein Cl, OR′, NH₂ aur OCOR′ rakhte hain, aur acyl chloride, ester, amide aur acid anhydride ke naam dete hain, har ek par mark hai ki woh acid se banta hai. Har step par list mein matching formula highlight hota hai.

Definition

Carbonyl group

Ek carbon atom jo oxygen atom se double bond se juda ho, $> C = O$ ; yeh aldehydes aur ketones ka functional group hai, aur carboxyl group ka hissa bhi.

ExamplePropanone, $C H_{3} C O C H_{3}$ , mein do methyl groups ke beech ek carbonyl group hota hai.

8.1 Nomenclature and Structure of Carbonyl Group

8.1.1 Nomenclature

Aldehydes aur ketones ke do tarah ke naam hote hain. Common names purane hain aur labs aur industry mein ab bhi sunne ko milte hain. IUPAC names systematic hain, isliye tum sirf structure se naam bana sakte ho, aur naam se structure.

Common names

Zyaadatar aldehydes apne common names usi carbon skeleton wale carboxylic acid se lete hain: -ic acid hatao aur aldehyde jodo. Formic acid se formaldehyde, acetic acid se acetaldehyde aur butyric acid se butyraldehyde banta hai. Chain par positions ko Greek letters se label karte hain, –CHO group ke bagal wale carbon se shuru karke: woh carbon α hai, uske baad wala β, phir γ aur δ. To $C l C H_{2} C H_{2} C H O$ β-chloropropionaldehyde hai.

Ketones ka naam carbonyl carbon par lage do groups ko alphabetical order mein likhkar aur ketone jodkar rakhte hain: $C H_{3} C O C H_{2} C H_{3}$ ethyl methyl ketone hai aur $(C H_{3})_{2} C H C O C H_{3}$ isopropyl methyl ketone hai. Do purane naam is pattern ko todte hain aur aaj bhi har jagah chalte hain: dimethyl ketone ke liye acetone, aur jin ketones ke carbonyl carbon par benzene ring ho unke liye ending -phenone, jaise acetophenone, $C_{6} H_{5} C O C H_{3}$ , aur butyrophenone, $C_{6} H_{5} C O C H_{2} C H_{2} C H_{3}$ . Substituent mark karne ke liye C=O se dono taraf bahar ki taraf Greek letters gino, do neighbouring carbons ke liye α aur α′, phir β aur β′, to $C l C H_{2} C O C H_{3}$ α-chloroacetone hai.

IUPAC names

Open-chain aldehyde ya ketone ka IUPAC naam chaar steps mein milta hai:

Parent chain dhoondo. Yeh woh sabse lambi chain hai jismein carbonyl carbon ho (aldehyde ke liye, khud –CHO carbon).
Numbering karo. Aldehyde carbon hamesha C1 hota hai, isliye uska locant kabhi likha nahi jaata. Ketone ke liye us end se number karo jisse C=O carbon ko chhota locant mile.
Ending chuno. Alkane naam ke last -e ko -al (aldehyde) ya -one (ketone) se replace karo; C=C ya C≡C ke liye -en- ya -yn- rakho, jaise but-3-en-2-one mein.
Substituents jodo prefixes ki tarah alphabetical order mein, har ek apne locant ke saath.
Rings. Ring ketone mein C=O carbon ko C1 gina jaata hai, jaise 3-methylcyclohexanone mein. Ring par laga –CHO group ring ka hissa nahi hota, isliye use suffix -carbaldehyde se dikhate hain, aur numbering us ring carbon se karte hain jis par woh laga hai: cyclopentanecarbaldehyde, 2-methylcyclohexanecarbaldehyde.
Benzene rings. $C_{6} H_{5} C H O$ ka jaana-pehchana naam benzaldehyde hi rehta hai, jise IUPAC benzenecarbaldehyde ki jagah accept karta hai; ring substituents ki numbering –CHO wale carbon se hoti hai, jaise 4-chlorobenzaldehyde mein.

Table 8.1Das aldehydes aur ketones aur unke naamNCERT Table 8.1 · p. 230

Formula	Naam
$C H_{3} C H_{2} C H O$	propanal (propionaldehyde)
$(C H_{3})_{2} C H C H_{2} C H O$	3-methylbutanal (isovaleraldehyde)
$C l C H_{2} C H_{2} C H O$	3-chloropropanal (β-chloropropionaldehyde)
$C_{6} H_{5} C H_{2} C H O$	2-phenylethanal (phenylacetaldehyde)
$C H_{2} = C (C H_{3}) C H O$	2-methylprop-2-enal (methacrolein)
$C l C_{6} H_{4} C H O$ (para)	4-chlorobenzaldehyde (p-chlorobenzaldehyde)
$C H_{3} C O C H_{2} C H_{3}$	butan-2-one (ethyl methyl ketone)
$C H_{3} C H_{2} C O C H_{2} C H_{3}$	pentan-3-one (diethyl ketone)
$(C H_{3})_{2} C H C O C H_{3}$	3-methylbutan-2-one (isopropyl methyl ketone)
$C_{6} H_{5} C O C H_{2} C H_{2} C H_{3}$	1-phenylbutan-1-one (butyrophenone)

8.1.2 Structure of the Carbonyl Group

Carbonyl carbon ke around bond angles naapo to woh lagbhag 120° aate hain, aur carbon aur usse jude teen atoms ek hi plane mein hote hain. Yeh geometry sp² hybridisation ki taraf ishaara karti hai: ek plane mein teen hybrid orbitals σ bonds banate hain, oxygen se aur baaki do groups se. Carbon ka bacha hua electron ek unhybridised p orbital mein rehta hai jo us plane se seedha upar khada hota hai. Oxygen bhi apna ek p orbital uske bagal mein line up karta hai, aur dono ka sideways overlap π bond banata hai, jiski electron density do lobes mein hoti hai, ek plane ke upar aur ek neeche (Fig. 8.2).

Angles bilkul barabar nahi hote. Methanal mein H–C–H angle lagbhag 116° hai aur har H–C=O angle lagbhag 122°: electron-rich double bond baaki do bonds ko thoda paas dhakel deta hai. Oxygen par do lone pairs bhi hote hain, jo tab important ho jaate hain jab acids aur Lewis acids us par attack karte hain.

4/4Oxygen π electrons ko apni taraf kheenchta hai: carbon δ+ ho jaata hai, oxygen δ−.

Fig. 8.2Carbonyl carbon sp² aur flat hai; π bond plane ke upar aur neeche hai, aur oxygen use apni taraf kheenchta hai.NCERT Fig. 8.1 · p. 231

Left panel, ek top view: ek carbon atom jo groups a aur b se juda hai aur O se double bond se, teen 120 degree angles mark kiye gaye hain, aur label hai sp2 carbon, flat. Right panel, ek edge-on view jismein molecular plane ek dashed line hai aur C aur O ek sigma bond se jude hain. Step 1 sirf woh sigma bond dikhata hai. Step 2 carbon par aur oxygen par ek-ek khada p orbital jodta hai, har ek ka ek lobe plane ke upar aur ek neeche. Step 3 unki jagah C–O axis ke upar aur neeche ek pi cloud dikhata hai, label pi bond. Step 4 pi cloud ko oxygen ki taraf jhuka deta hai, C par delta plus aur O par delta minus label lagata hai, aur C se O ki taraf point karta ek dipole arrow banata hai.

Oxygen (electronegativity 3.4) shared electrons ko carbon (2.6) se kahin zyada mazbooti se pakadta hai, aur dheele bandhe π electrons sabse zyada kheenche jaate hain. Carbonyl carbon par partial positive charge aur oxygen par partial negative charge reh jaata hai. Ise do resonance structures describe karte hain: poore C=O double bond wala covalent form, aur $C^{+}$ aur $O^{-}$ wala charge-separated form. Asli molecule ek hybrid hai jo zyaadatar pehla hai lekin usmein doosre ka bhi achha-khaasa hissa hai.

Carbonyl group ke do resonance forms

\begin{aligned} > C = O \overset{}{\leftrightarrow} \\ > C^{+} - O^{-} \end{aligned}

Isse do predictions nikalte hain. δ+ carbon electrophilic hai (ek Lewis-acid site), isliye electron-rich reagents, yaani nucleophiles, us par attack karte hain. δ− oxygen, apne lone pairs ke saath, nucleophilic aur weakly basic hai (ek Lewis-base site), isliye protons aur Lewis acids wahin judte hain. Aur kyunki bond itna polar hai, carbonyl compounds ke dipole moments bade hote hain: methanal ke lagbhag 2.3 D se propanone ke 2.9 D tak, jo methoxymethane (1.3 D) jaise ethers ke do guna se bhi zyada hai.

SimulationC=O bond partial charges ke ek pair ki tarah

Stage ke beech mein do fixed point charges aamne-saamne hain: carbonyl carbon ke liye left mein ek positive charge aur oxygen ke liye right mein ek negative charge, aur unke around field lines aur equipotential curves. Ek chhota negative test charge, jo nucleophile ko dikhata hai, kahin bhi drag kiya ja sakta hai; ek arrow aur readout us par lagne wale force ka size aur direction batate hain.

Fig. 8.3+ charge δ+ carbonyl carbon ko dikhata hai aur − charge δ− oxygen ko. Chhota negative probe paas aate nucleophile, jaise

C N^{-}

, ka role nibhata hai.

Try karo

Negative probe ko upper left se dheere-dheere pair ki taraf drag karo. Woh kis atom ki taraf khinchta hai?
Probe ko oxygen end ke thoda aage, dono charges se guzarti line par rakho. Woh attract hota hai ya door dhakela jaata hai?
Probe ko carbon charge ke theek upar rakho aur force ko oxygen ke upar utni hi doori par force se compare karo.

Practice · 1 question

Practice 8.1: answers ke saath

1
Short answerEasyNCERT Intext Question 8.1
Har compound ka condensed structural formula likho.
1. α-Chloropropionaldehyde
  Solution dikhao
  $C H_{3} C H C l C H O$ : chlorine –CHO ke bagal wale carbon par hai (IUPAC: 2-chloropropanal).
2. 4-Hydroxypentan-2-one
  Solution dikhao
  $C H_{3} C O C H_{2}$ – $C H (O H) C H_{3}$
3. Hexane-2,5-dione
  Solution dikhao
  $C H_{3} C O C H_{2}$ – $C H_{2} C O C H_{3}$ : do C=O groups, C2 aur C5 par.
4. 3-Ethylcyclohexanone
  Solution dikhao
  Ek six-membered ring jismein C=O carbon C1 hai aur C3 par, yaani usse do carbons door, ek ethyl group hai.
5. Ethyl isopropyl ketone
  Solution dikhao
  $C H_{3} C H_{2} C O$ – $C H (C H_{3})_{2}$ (IUPAC: 2-methylpentan-3-one).
6. 4-Methylbenzophenone
  Solution dikhao
  $C_{6} H_{5} C O$ – $C_{6} H_{4} C H_{3}$ : ek ring simple phenyl hai, doosri ring par C=O ke para position mein $C H_{3}$ hai.

8.2 Preparation of Aldehydes and Ketones

C=O group banane ke kai tarike hain. Kuch tarike sirf starting material ke hisaab se aldehyde ya ketone dete hain; kuch sirf ek family ke liye khaas hain. Aldehyde banane mein hamesha ek hi challenge hota hai: reaction ko us point par rokna jahan aldehyde aage oxidise hokar acid na ban jaaye, ya aage reduce hokar alcohol na ban jaaye.

8.2.1 Preparation of Aldehydes and Ketones

Alcohols ko oxidise karke. Jaisa tumne Unit 7 mein dekha, primary alcohol oxidise hokar aldehyde aur secondary alcohol ketone banta hai. Aldehyde ke liye pyridinium chlorochromate (PCC) jaisa mild oxidant chuna jaata hai, taaki reaction wahin ruk jaaye; ketone aage oxidation resist karta hai, isliye acidified dichromate achha kaam karta hai.

Alcohols ko dehydrogenate karke. Industry mein volatile alcohol ki vapour ko garam copper (lagbhag 573 K) ya silver ke upar se guzaarte hain. Hydrogen nikal jaata hai aur kisi oxidant ki zaroorat nahi padti. Primary alcohol se aldehyde aur secondary alcohol se ketone milta hai.

Butan-2-ol se butanone

\begin{aligned} C H_{3} C H (O H) C_{2} H_{5} \\ \overset{C u, 573 K}{\to} \\ C H_{3} C O C_{2} H_{5} + H_{2} \end{aligned}

Hydrocarbons se. Ozonolysis alkene ko uske C=C par tod deta hai. Zinc dust aur water ke saath work-up ke baad, purane double bond ke har carbon par ek C=O aa jaata hai, isliye products aldehydes, ketones ya ek-ek dono hote hain, yeh is par depend karta hai ki un carbons se kya juda tha. Jaise 2-methylbut-2-ene se propanone aur ethanal milte hain.

2-methylbut-2-ene ka ozonolysis

\begin{aligned} (C H_{3})_{2} C = C H C H_{3} \\ \to_{2 \cdot Z n, H_{2} O}^{1 \cdot O_{3}} \\ (C H_{3})_{2} C O \\ + C H_{3} C H O \end{aligned}

Dilute sulphuric acid aur mercury(II) salt ke saath garam karne par alkynes mein water add hota hai. Pehla product, ek enol, turant rearrange hokar carbonyl compound ban jaata hai. Kyunki oxygen Markovnikov's rule ke hisaab se carbon par jaata hai, sirf ethyne hi aakhir mein aldehyde (ethanal) banata hai; baaki har alkyne ketone deta hai, jaise propyne se propanone milta hai.

Propyne ka hydration

\begin{aligned} C H_{3} C \equiv C H + H_{2} O \\ \overset{H g^{2 +}, H_{2} S O_{4}}{\to} \\ C H_{3} C O C H_{3} \end{aligned}

8.2.2 Preparation of Aldehydes

Aldehyde ek oxidation ladder ki beech wali seedhi hai, jiske neeche alcohol aur upar acid hai. Yahan har method isi tarah design kiya gaya hai ki reaction beech wali seedhi par hi ruke.

Acyl chlorides se (Rosenmund reduction). Normal palladium par hydrogen acyl chloride ko seedha alcohol tak reduce kar deta. Palladium ko barium sulphate par failane se woh poison ho jaata hai, aur bas itna active rehta hai ki Cl ko H se badal sake, isliye aldehyde bach jaata hai.

Butanoyl chloride ka Rosenmund reduction

\begin{aligned} C_{3} H_{7} C O C l + H_{2} \\ \overset{P d / B a S O_{4}}{\to} \\ C_{3} H_{7} C H O + H C l \end{aligned}

Nitriles se (Stephen reaction). Tin(II) chloride aur hydrochloric acid nitrile ko sirf imine tak reduce karte hain, jo uske salt ke roop mein rehta hai. Phir garam water C=NH group ko hydrolyse karke C=O bana deta hai.

Stephen reaction: propanenitrile se propanal

\begin{aligned} C_{2} H_{5} C \equiv N \\ \overset{S n C l_{2}, H C l}{\to} \\ C_{2} H_{5} C H = N H \\ \overset{H_{3} O^{+}}{\to} C_{2} H_{5} C H O \end{aligned}

Ek zyada modern reagent, diisobutylaluminium hydride (DIBAL-H, $[(C H_{3})_{2} C H C H_{2}]_{2} A l H$ ), thande mein use karne par nitrile ya ester ko sirf ek hydride ion deta hai; phir water aldehyde ko free kar deta hai. Methyl hexanoate jaisa ester hexanal deta hai.

Ester ka DIBAL-H reduction (C₅H₁₁ = pentyl)

\begin{aligned} C_{5} H_{11} C O O C H_{3} \\ \to_{2 \cdot H_{2} O}^{1 \cdot D I B A L - H} \\ C_{5} H_{11} C H O \end{aligned}

Toluene aur benzene se. Garam $K M n O_{4}$ jaisa strong oxidant toluene ke methyl group ko seedha –COOH bana deta hai, aldehyde se aage nikal jaata hai. Teen methods isse bachte hain: pehle – $C H_{3}$ ko aise group mein badalte hain jise reagent aage oxidise nahi kar sakta, phir water mein –CHO free karte hain (Fig. 8.4):

Etard reaction. $C S_{2}$ mein chromyl chloride, $C r O_{2} C l_{2}$ , methyl group ko ek brown chromium complex mein badal deta hai; hydrolysis se benzaldehyde milta hai.
Ethanoic anhydride mein chromic oxide. $C r O_{3}$ methyl group ko oxidise karta hai aur anhydride use thande mein diacetate $C_{6} H_{5} C H (O C O C H_{3})_{2}$ ke roop mein pakad leta hai; aqueous acid ke saath garam karne par aldehyde free ho jaata hai.
Side-chain chlorination. Light mein chlorine methyl group ke do H atoms ko replace karta hai, aur benzal chloride, $C_{6} H_{5} C H C l_{2}$ , banta hai. Water ke saath boil karne par $C H C l_{2}$ group –CHO ban jaata hai. Commercial benzaldehyde ka bada hissa isi tarah banta hai.

2/4Chromyl chloride chromium complex banata hai; hydrolysis se benzaldehyde milta hai.

Fig. 8.4Aldehyde par rukna: side-chain carbon ko ek protected form mein park karo, phir water se –CHO free karo.NCERT p. 232

Ek row mein chaar boxes benzene ring par side chain ko badhte oxidation level par dikhate hain: –CH₃ (toluene), –CH₂OH (alcohol), –CHO (aldehyde, target ke roop mein highlighted) aur –COOH (acid). Step 1: KMnO₄, heat label wala ek dashed arrow –CH₃ se seedha –COOH tak jaata hai, aldehyde ko skip karke. Steps 2 se 4 mein har baar arrow 1 –CH₃ se neeche ek intermediate box tak aur arrow 2 wahan se upar –CHO tak jaata hai: step 2 mein Etard complex (CS₂ mein CrO₂Cl₂, phir H₃O⁺), step 3 mein diacetate –CH(OCOCH₃)₂ (ethanoic anhydride ke saath CrO₃, phir H₃O⁺), step 4 mein dichloride –CHCl₂ (light mein Cl₂, phir water aur heat).

Gattermann–Koch reaction. Benzene ko khud bhi formylate kiya ja sakta hai: anhydrous aluminium chloride aur thode copper(I) chloride ke saath carbon monoxide aur hydrogen chloride ring par seedha ek –CHO group laga dete hain. Isi tarah toluene se mainly 4-methylbenzaldehyde milta hai.

Gattermann–Koch reaction

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

8.2.3 Preparation of Ketones

Acyl chlorides aur dialkylcadmium se. Grignard reagent acyl chloride par attack karta hai, lekin woh apne banaye ketone par bhi aage attack kar dega. Pehle use cadmium chloride ke saath treat karne se dialkylcadmium banta hai, jo ek naram reagent hai: yeh acyl chloride se react karta hai aur ketone ko chhod deta hai.

Dimethylcadmium banana

\begin{aligned} 2 C H_{3} M g B r \\ + C d C l_{2} \\ \overset{}{\to} (C H_{3})_{2} C d \\ + 2 M g (B r) C l \end{aligned}

Butanoyl chloride se pentan-2-one

\begin{aligned} 2 C_{3} H_{7} C O C l \\ + (C H_{3})_{2} C d \\ \overset{}{\to} 2 C_{3} H_{7} C O C H_{3} \\ + C d C l_{2} \end{aligned}

Nitriles aur Grignard reagents se. RMgX ka carbon, jo carbanion ki tarah behave karta hai, C≡N ke carbon par add hota hai. Bana hua imine salt aqueous acid se hydrolyse hota hai, aur =NMgX ki jagah =O aa jaata hai. Ethanenitrile aur ethylmagnesium bromide se butanone milta hai.

Nitrile + Grignard reagent

\begin{aligned} C H_{3} C \equiv N \\ + C_{2} H_{5} M g B r \\ \overset{e t h e r}{\to} imine salt \\ \overset{H_{3} O^{+}}{\to} C H_{3} C O C_{2} H_{5} \end{aligned}

Arenes se (Friedel–Crafts acylation). Acyl chloride aur anhydrous $A l C l_{3}$ acylium ion, $R C \equiv O^{+}$ , banate hain, jo ek electrophile hai aur ring par substitute hota hai. Product ek aryl ketone hota hai. Kyunki iska C=O group ring ko deactivate karta hai, ek acyl group lagne ke baad reaction ruk jaata hai, Friedel–Crafts alkylation ki tarah nahi. (Acyl chloride ki jagah acid anhydrides bhi le sakte hain.)

Toluene ka acylation: mainly 4-methylacetophenone

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

Example 8.1NCERT Example 8.1 · p. 234

Reagents chunna

Har change ke liye ek reagent, ya reagents ka chhota sequence, batao: (a) 3-phenylpropan-1-ol se 3-phenylpropanal; (b) 4-methylcyclohexanol se 4-methylcyclohexanone; (c) 4-chlorotoluene se 4-chlorobenzaldehyde; (d) benzonitrile se benzaldehyde; (e) ethanoyl chloride se ethanal; (f) 2,3-dimethylbut-2-ene se propanone.

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

Practice · 1 question

Practice 8.2: answers ke saath

1
Short answerMediumNCERT Intext Question 8.2
Har reaction ke main organic product ka structure aur naam likho.
1. Propanoyl chloride aur anhydrous $A l C l_{3}$ ke saath methoxybenzene
  Solution dikhao
  Friedel–Crafts acylation. Methoxy group para position ki taraf direct karta hai, isliye main product $C H_{3} O C_{6} H_{4}$ – $C O C H_{2} C H_{3}$ , 1-(4-methoxyphenyl)propan-1-one hai.
2. Benzoyl chloride ke do moles ke saath $(C_{2} H_{5})_{2} C d$
  Solution dikhao
  Har ethyl group ek Cl ko replace karta hai: $C_{6} H_{5} C O C_{2} H_{5}$ , 1-phenylpropan-1-one (propiophenone).
3. Water, $H g^{2 +}$ aur $H_{2} S O_{4}$ ke saath pent-1-yne
  Solution dikhao
  Markovnikov hydration O ko C2 par lagata hai: $C H_{3} C O C H_{2} C H_{2} C H_{3}$ , pentan-2-one.
4. Ethanoic anhydride mein $C r O_{3}$ ke saath 3-bromotoluene, phir $H_{3} O^{+}$
  Solution dikhao
  Methyl group diacetate ke roop mein pakda jaata hai aur –CHO ke roop mein free hota hai: 3-bromobenzaldehyde, $B r C_{6} H_{4} C H O$ .

8.3 Physical Properties

Sirf do sabse chhote members ko bottle mein rakhna mushkil hai: methanal 254 K par boil hota hai, isliye use water mein ghola hua becha jaata hai, aur ethanal 293 K par, jo ek garam kamre ke temperature se thoda kam hai. Isse bade har aldehyde ya ketone room temperature par liquid ya solid hota hai.

Jab molar masses lagbhag barabar hon, to molecules ke beech ke forces boiling point decide karte hain (Fig. 8.5). Hexane jaise hydrocarbon mein sirf weak London forces hote hain. Ether thoda polar hota hai, lekin uska oxygen do carbon groups ke beech chhupa rehta hai. Aldehydes aur ketones mein strongly polar C=O hota hai, isliye paas ke molecules δ+ se δ− line up hote hain, aur yeh dipole–dipole attraction boiling point ko 30 K se zyada badha deta hai. Lekin yeh aapas mein hydrogen bond nahi bana sakte, kyunki inke oxygen par hydrogen nahi hota. Utne hi mass wala alcohol bana sakta hai, isliye woh aur bhi upar boil hota hai.

4/4–COOH hydrogen-bonded pairs banata hai: 437 K (8.8 dekho).

Fig. 8.5Same size, alag forces: polarity lagbhag 30 K jodti hai, aur O–H group kahin zyada.NCERT p. 235

Ek horizontal temperature axis lagbhag 330 K se 450 K tak jaata hai, har compound ke liye ek row hai, sabka molar mass 86 se 88 g/mol. Step 1 hexane ko 342 K par aur 1-methoxybutane ko 343 K par dikhata hai, note ke saath: weak London forces. Step 2 pentanal ko 376 K par aur pentan-2-one ko 375 K par circles ke roop mein jodta hai, note: dipole–dipole attraction. Step 3 pentan-1-ol ko 411 K par triangle ke roop mein jodta hai, note: hydrogen bonds. Step 4 butanoic acid ko 437 K par diamond ke roop mein jodta hai, note: hydrogen-bonded pairs.

Carbonyl oxygen hydrogen bond donate nahi kar sakta, lekin uske lone pairs water se ek hydrogen bond accept kar sakte hain. Itna kaafi hai ki methanal, ethanal aur propanone water mein kisi bhi proportion mein ghul jaate hain. Phir chain badhne ke saath solubility tezi se girti hai, kyunki water mein zyada se zyada non-polar $C H_{2}$ groups fit karne padte hain. 100 mL water mein lagbhag 7 g butanal ghulta hai, lekin hexanal 1 g se bhi kaafi kam.

Tumhari naak bhi isi series ko follow kar sakti hai. Methanal aur ethanal tez aur irritating hote hain, lekin aath se das carbon atoms wale aldehydes mein citrus peel jaisi khushboo hoti hai; perfumers inhe, jasmone (jasmine) aur muscone (musk) jaise ketones ke saath, bahut thodi matra mein use karte hain.

Example 8.2NCERT Example 8.2 · p. 235

Boiling points ki ranking

Hexan-1-ol, heptane, pentanoic acid aur hexanal ko badhte boiling point ke order mein lagao. Inke molar masses sab 100 aur 102 g/mol ke beech hain.

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

8.4 Chemical Reactions

Kyunki aldehydes aur ketones mein carbonyl group common hai, inke zyaadatar reactions bhi common hain. Inhe paanch groups mein baanta jaata hai: nucleophilic addition, reduction, oxidation, α-hydrogens ke reactions, aur kuch aur (Cannizzaro reaction aur aromatic ring par substitution).

Nucleophilic addition reactions

Alkene ka C=C bond non-polar aur electrons se bhara hota hai, isliye us par pehla attack electrophile karta hai. C=O bond iska ulta hai: iske carbon par electrons ki kami hai, isliye pehla attack nucleophile karta hai, aur overall change double bond ke across ek addition hota hai. Yeh nucleophilic addition aldehydes aur ketones ka signature reaction hai.

Mechanism

Electrons ko follow karo (Fig. 8.6):

Attack (slow). Nucleophile ka ek lone pair carbonyl carbon se bond banana shuru karta hai. Yeh molecular plane ke upar ya neeche se aata hai, jahan π orbital hai, C=O axis se lagbhag 107° wali line par.
Push. π electron pair oxygen par chala jaata hai, jo electronegative hone ki wajah se use achhe se sambhaal leta hai. Ab carbon par chaar groups hain: woh flat (sp²) se tetrahedral (sp³) ho gaya hai, aur oxygen ek alkoxide, – $O^{-}$ , hai.
Protonation (fast). Alkoxide oxygen solvent se ya acid se $H^{+}$ le leta hai.

To nucleophile aakhir mein carbon par aur hydrogen oxygen par aa jaata hai.

1/4 $N u^{-}$ plane ke upar se aata hai; π electrons oxygen par chale jaate hain.

Fig. 8.6Nucleophilic addition: δ+ carbon par attack, phir oxygen ka protonation.NCERT Fig. 8.2 · p. 236

Step 1 ek flat carbonyl group dikhata hai: carbon groups a aur b se juda hai aur O se double bond se, C par delta plus aur O par delta minus. Ek nucleophile, Nu minus, carbon ke upar ek dashed approach line par hai jo C=O bond ke saath lagbhag 107 degrees banati hai; curved arrows Nu se C ki taraf aur C=O bond se O ki taraf jaate hain. Step 2 tetrahedral alkoxide dikhata hai: Nu ab C se juda hai, a wedge par, b hashed bond par aur O minus single bond par, labels sp3 aur slow step. Step 3 dikhata hai ki solvent se H plus O minus par aakar O–H group banata hai, label fast. Step 4 carbon par Nu aur oxygen par H ko highlight karta hai: Nu–H C=O ke across add ho gaya.

Definition

Nucleophilic addition

Aisa reaction jismein nucleophile C=O group ke δ+ carbon se bond banata hai aur phir oxygen ek proton leta hai, jisse Nu aur H double bond ke across add ho jaate hain.

ExamplePropanone + HCN (thode se base ke saath) se cyanohydrin, $(C H_{3})_{2} C (O H) C N$ , banta hai.

Reactivity

Methanal, ethanal aur propanone ko line mein rakho (Fig. 8.7). Har baar jab carbonyl carbon par ek hydrogen ko methyl group se replace karte hain, do cheezein badalti hain. Pehli, jagah: methyl group H se kahin bada hai, isliye nucleophile ke liye carbon tak pahunchna mushkil ho jaata hai. Tetrahedral product, jismein ek carbon ke around chaar groups bhare hain, bhi zyada crowded hota hai. Doosri, charge: alkyl groups carbonyl carbon ki taraf electron density dete hain (+I effect), isliye uska δ+ kam ho jaata hai. Dono changes reaction ko slow karte hain. Isi wajah se aldehydes generally ketones se tez react karte hain, aur methanal, jismein koi alkyl group nahi hai, sabse tez.

4/4Dono effects se methanal > ethanal > propanone milta hai.

Fig. 8.7Har alkyl group carbonyl carbon ko crowd karta hai aur use electrons deta hai, isliye reactivity methanal se ketones tak girti hai.NCERT p. 236

Teen carbonyl compounds aamne-saamne hain: do H atoms wala methanal, ek CH₃ aur ek H wala ethanal, aur do CH₃ groups wala propanone. Step 1 simple structures dikhata hai. Step 2 groups ke around dashed halos banata hai, H ke liye chhote aur CH₃ ke liye bade, jo dikhate hain ki propanone ka carbonyl carbon sabse crowded hai. Step 3 har CH₃ group se carbonyl carbon ki taraf orange arrows jodta hai aur carbon par delta plus label lagata hai, jo methanal ke liye bada, ethanal ke liye medium aur propanone ke liye chhota print hai. Step 4 har molecule ke neeche bars jodta hai: methanal ke liye sabse lamba (sabse tez), ethanal ke liye medium (dheema), propanone ke liye sabse chhota (sabse dheema).

Conjugation bhi reactivity kam karta hai. Jab C=O group seedha benzene ring se juda ho, to ring ke π electrons usmein delocalise ho jaate hain, jo carbonyl carbon ki taraf electron density bhejte hain. Isliye aromatic aldehydes aur ketones milte-julte aliphatic waalon se kam reactive hote hain, jabki ring par – $N O_{2}$ jaise electron-withdrawing groups unhe zyada reactive bana dete hain.

Example 8.3NCERT Example 8.3 · p. 236

Kya conjugation attack ko slow karta hai?

HCN ke saath kaun tez react karta hai: benzaldehyde, $C_{6} H_{5} C H O$ , ya phenylethanal, $C_{6} H_{5} C H_{2} C H O$ ? Samjhao.

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

Kuch important addition reactions

(a) Hydrogen cyanide. Product ek cyanohydrin hota hai, jismein pehle wale carbonyl carbon par –OH aur –CN hote hain. HCN ek weak acid hai, isliye pure HCN mein cyanide ions na ke barabar hote hain, aur akele mein yeh bahut dheere add hota hai. Asli attacker $C N^{-}$ hai: thoda sa base (ya KCN) ise deta hai, phir bana hua alkoxide HCN se ek proton wapas le leta hai, aur isse agle molecule ke liye $C N^{-}$ phir ban jaata hai. Chemists cyanohydrins ko isliye pasand karte hain kyunki naya –CN carbon baad mein –COOH (hydrolysis se) ya $- C H_{2} N H_{2}$ (reduction se) ban sakta hai, jisse chain mein ek carbon judta hai.

Propanone cyanohydrin

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

(b) Sodium hydrogensulphite. Maan lo ek aldehyde ko doosre organic liquids se alag karna hai. Mixture ko saturated aqueous $N a H S O_{3}$ ke saath hilane se aldehyde ek crystalline addition compound ban jaata hai jo water mein ghul jaata hai. Baaki liquids dho diye jaate hain, aur adduct ko dilute acid ya alkali ke saath garam karne se pure aldehyde wapas mil jaata hai. Yeh isliye kaam karta hai kyunki addition reversible hai. Yeh aldehydes aur kuch unhindered methyl ketones ke liye theek hai; zyaadatar ketones, jo do carbon groups se crowded hain, bahut kam adduct banate hain.

Hydrogensulphite addition compound

\begin{aligned} R C H O + N a H S O_{3} \\ \overset{}{⇌} \\ R C H (O H) S O_{3} N a \end{aligned}

(c) Grignard reagents. Jaise Unit 7 mein, RMgX C=O group par add hota hai aur phir hydrolysis se alcohol milta hai: methanal se primary alcohol, baaki aldehydes se secondary alcohols, aur ketones se tertiary alcohols.

Propanone se 2-methylbutan-2-ol

\begin{aligned} (C H_{3})_{2} C O \\ + C_{2} H_{5} M g B r \\ \to_{2 \cdot H_{3} O^{+}}^{1 \cdot e t h e r} \\ (C H_{3})_{2} C (O H) C_{2} H_{5} \end{aligned}

(d) Alcohols. Alcohol ek weak nucleophile hai, isliye akele mein woh C=O group ko mushkil se chhoota hai. Dry HCl gas carbonyl oxygen ko protonate karke yeh badal deti hai, aur protonated C=O par aasani se attack hota hai. Ek alcohol molecule se hemiacetal banta hai, ek carbon jis par –OH aur –OR dono hote hain. Unhi acidic conditions mein woh –OH water ke roop mein nikal jaata hai aur uski jagah doosra –OR aa jaata hai, aur acetal banta hai, jismein ek carbon par do –OR groups hote hain. Ketones ko usually ethane-1,2-diol ke saath treat karte hain: iske dono –OH groups ek hi carbon se judte hain aur ek five-membered ring band karte hain, jo ek cyclic (ethylene glycol) ketal hai.

Ethanal: pehle hemiacetal, phir acetal

\begin{aligned} C H_{3} C H O + C H_{3} O H \\ \overset{H C l}{⇌} \\ C H_{3} C H (O H) O C H_{3} \\ \overset{C H_{3} O H, H^{+}}{\to} \\ C H_{3} C H (O C H_{3})_{2} \\ + H_{2} O \end{aligned}

Propanone ethylene glycol ketal (2,2-dimethyl-1,3-dioxolane)

\begin{aligned} (C H_{3})_{2} C O \\ + H O C H_{2} C H_{2} O H \\ \overset{H^{+}}{⇌} cyclic ketal \\ + H_{2} O \end{aligned}

Acetals aur ketals bases aur nucleophiles ke saath tike rehte hain, lekin garam aqueous acid unhe wapas carbonyl compound aur alcohol mein tod deta hai. Isliye jab molecule ka koi aur hissa badla ja raha ho, tab yeh C=O group par useful temporary caps ka kaam karte hain.

(e) Ammonia aur uske derivatives. $H_{2} N - Z$ type ke nitrogen nucleophile ke saath addition ke baad elimination hota hai: addition product (ek carbinolamine) water kho deta hai, aur C=O ki jagah C=N–Z aa jaata hai. Har step reversible hai aur acid se tez hota hai, lekin water ka nikalna fast hai, isliye C=N product jeet jaata hai. Mildly acidic conditions (lagbhag pH 4–5) sabse achhi rehti hain: itna acid ki C=O activate ho jaaye, par itna nahi ki nitrogen ka lone pair $H_{3} N^{+} - Z$ ke roop mein bandh jaaye.

Addition, phir water ka elimination

\begin{aligned} R_{2} C = O + H_{2} N - Z \\ \overset{}{⇌} R_{2} C (O H) - N H Z \\ \overset{}{\to} R_{2} C = N - Z \\ + H_{2} O \end{aligned}

Table 8.2Reagents

H_{2} N

–Z aur propanone ke saath unse kya banta haiNCERT Table 8.2 · p. 238

Reagent (Z)	Propanone se product
ammonia (Z = H)	imine, $(C H_{3})_{2} C = N H$
methylamine (Z = $C H_{3}$ )	substituted imine (Schiff base), $(C H_{3})_{2} C = N C H_{3}$
hydroxylamine (Z = OH)	oxime, $(C H_{3})_{2} C = N O H$
hydrazine (Z = $N H_{2}$ )	hydrazone, $(C H_{3})_{2} C = N N H_{2}$
phenylhydrazine (Z = $N H C_{6} H_{5}$ )	phenylhydrazone
2,4-dinitrophenylhydrazine	2,4-dinitrophenylhydrazone (2,4-DNP derivative)
semicarbazide (Z = $N H C O N H_{2}$ )	semicarbazone, $(C H_{3})_{2} C = N N H C O N H_{2}$

2,4-DNP derivatives chamakdaar rang ke solids ke roop mein crystallise hote hain, yellow se lekar deep red tak, aur inke melting points sharp hote hain. Isliye 2,4-DNP reagent (Brady's reagent) ke saath coloured precipitate aldehyde ya ketone ka ek quick test hai, aur purified solid ka melting point yeh pehchanne mein madad karta hai ki woh kaunsa compound hai.

Quick check

4 mein se 1

Ketone par nucleophilic addition ke dauraan carbonyl carbon ke hybridisation ka kya hota hai?

sp³ → sp²sp² → sp³sp² hi rehta haisp → sp²

Answer dekho

Answer (B) sp² → sp³

Flat sp² carbon, nucleophile ke judte hi tetrahedral sp³ ban jaata hai. Ulta tabhi hota jab koi group nikalkar double bond phir se banata.

Reduction

Alcohols tak. Sodium borohydride, $N a B H_{4}$ , ya lithium aluminium hydride, $L i A l H_{4}$ , carbonyl carbon ko ek hydride ion deta hai (yeh bhi ek nucleophilic addition hai), aur work-up oxygen par $H^{+}$ jodta hai. Nickel, platinum ya palladium par hydrogen bhi yahi kaam karta hai. Aldehydes se primary alcohols aur ketones se secondary alcohols milte hain.

Hydrocarbons tak. Kabhi-kabhi oxygen ko poori tarah hatana hota hai, yaani C=O ko $C H_{2}$ banana. Yeh do named reactions karte hain, ek acid mein aur ek base mein, taaki chemist woh chun sake jise molecule ka baaki hissa jhel sake:

Compare

C=O ko CH₂ banane ke do tarike

Clemmensen reduction

zinc amalgam (Zn–Hg) aur concentrated HCl, garam karke
strongly acidic
acid mein stable molecules ke liye theek
C=O → $C H_{2}$ + $H_{2} O$

Wolff–Kishner reduction

pehle hydrazine hydrazone banata hai
phir ethylene glycol (b.p. 470 K) mein KOH ke saath garam karte hain
strongly basic
C=O → $C H_{2}$ + $N_{2}$

Clemmensen: butanone se butane

\begin{aligned} C H_{3} C O C H_{2} C H_{3} \\ \to_{c o n c \cdot H C l}^{Z n - H g} \\ C H_{3} C H_{2} C H_{2} C H_{3} \end{aligned}

Wolff–Kishner: acetophenone se ethylbenzene

\begin{aligned} C_{6} H_{5} C O C H_{3} \\ + N_{2} H_{4} \\ \overset{}{\to} hydrazone \\ + H_{2} O \\ \overset{K O H, h e a t}{\to} \\ C_{6} H_{5} C H_{2} C H_{3} + N_{2} \end{aligned}

Oxidation

Yahan aldehydes aur ketones ke raaste alag ho jaate hain. Aldehyde ke carbonyl carbon par abhi bhi ek hydrogen hai, aur woh C–H bond aasani se oxidise ho jaata hai. Lagbhag koi bhi oxidant aldehyde ko carboxylic acid bana deta hai: acidified dichromate, permanganate, yahan tak ki hawa ki oxygen bhi (benzaldehyde ki khuli bottle mein dheere-dheere benzoic acid ke crystals bhar jaate hain). Jo naram reagents ketones ko chhoote bhi nahi, woh bhi aldehydes ko oxidise kar dete hain, aur inse useful tests bante hain.

Aldehydes oxidise hokar acids bante hain

R C H O \overset{[O]}{\to} R C O O H

Ketone mein aisa hydrogen nahi hota. Sirf high temperature par strong oxidants hi us par attack karte hain, aur tab C=O ke bagal wala ek C–C bond tootna padta hai. Yeh break kisi bhi side ho sakta hai, isliye ketone usually acids ka mixture deta hai, aur har acid mein ketone se kam carbon atoms hote hain. Jaise hexan-3-one se ethanoic acid aur butanoic acid, ya propanoic acid ke do molecules mil sakte hain.

Is fark se simple tests bante hain jo aldehyde ko ketone se alag pehchante hain (Fig. 8.8).

Tollens' test. Reagent excess aqueous ammonia mein ghula silver nitrate hai, isliye silver alkaline solution mein complex ion $[A g (N H_{3})_{2}]^{+}$ ke roop mein hota hai. Aldehyde is complex ko reduce karta hai: metallic silver glass par mirror ki tarah jam jaata hai, aur aldehyde apna carboxylate ion ban jaata hai. Reagent use se theek pehle thodi matra mein banaya jaata hai (neeche wali caution dekho), aur ketones ise waisa hi chhod dete hain.

Tollens' test

\begin{aligned} R C H O \\ + 2 [A g (N H_{3})_{2}]^{+} \\ + 3 O H^{-} \\ \overset{}{\to} R C O O^{-} \\ + 2 A g ↓ + 2 H_{2} O \\ + 4 N H_{3} \end{aligned}

Fehling's test. Fehling's reagent do bottles mein aata hai jinhe sirf zaroorat padne par milate hain. Ek mein copper(II) sulphate solution hota hai. Doosri mein sodium hydroxide mein sodium potassium tartrate (Rochelle salt) hota hai, aur tartrate $C u^{2 +}$ ko hydroxide ke roop mein precipitate hone dene ke bajaay deep blue complex ke roop mein solution mein rakhta hai. Mixture ko aliphatic aldehyde ke saath boil karo to copper(I) oxide red-brown solid ke roop mein neeche baith jaata hai. Benzaldehyde aur doosre aromatic aldehydes yeh test fail karte hain, aur ketones bhi.

Fehling's test

\begin{aligned} R C H O + 2 C u^{2 +} \\ + 5 O H^{-} \\ \overset{}{\to} R C O O^{-} \\ + C u_{2} O ↓ + 3 H_{2} O \end{aligned}

Haloform reaction. $C H_{3} C O^{-}$ group wale compound ko iodine aur sodium hydroxide ke saath garam karo, to iodoform, $C H I_{3}$ , ke halke yellow crystals dikhte hain, jinki ek khaas antiseptic smell hoti hai. Is test ke peeche ek two-stage reaction hai (haloform reaction). Base aur halogen methyl group ke teeno hydrogens ko halogen se replace karte hain, aur phir hydroxide $C X_{3}$ group ko $C H X_{3}$ ke roop mein kaat deta hai, aur ek carbon chhote acid ka carboxylate bach jaata hai. Chlorine aur bromine, sodium hypochlorite aur hypobromite ke roop mein, isi tarah react karte hain.

Haloform reaction (X = Cl, Br, I)

\begin{aligned} R C O C H_{3} + 3 N a O X \\ \overset{}{\to} R C O C X_{3} \\ + 3 N a O H \\ R C O C X_{3} + N a O H \\ \overset{}{\to} R C O O N a \\ + C H X_{3} \end{aligned}

Aldehydes mein sirf ethanal mein $C H_{3} C O^{-}$ group hota hai. $C H_{3} C H (O H)^{-}$ group wale alcohols bhi respond karte hain, kyunki hypoiodite pehle unhe $C H_{3} C O^{-}$ tak oxidise kar deta hai: ethanol aur propan-2-ol iodoform dete hain, propan-1-ol nahi deta. Kyunki C=C bonds par attack nahi hota, yeh reaction unsaturated methyl ketone ko unsaturated acid mein bhi badal sakta hai.

4/4 $C H_{3} C O$ – ya $C H_{3} C H (O H)$ – yellow $C H I_{3}$ crystals deta hai.

Fig. 8.8Har test mein positive result kaisa dikhta hai.NCERT p. 239

Teen test tubes ek row mein khade hain, headings ke neeche: Tollens' ([Ag(NH₃)₂]⁺), Fehling's (Cu²⁺ + tartrate) aur iodoform (I₂ + NaOH). Step 1 sirf reagents dikhata hai: colourless, deep blue aur halka brown. Step 2 pehli tube ke andar grey silver mirror ki parat chadha deta hai, label: silver mirror, any aldehyde. Step 3 doosri tube ke bottom mein red-brown solid jodta hai aur blue ko halka karta hai, label: red-brown Cu₂O, aliphatic aldehyde. Step 4 teesri tube ke bottom mein yellow crystals jodta hai, label: yellow CHI₃, CH₃CO– group.

Try karke dekho

Kaunsi sugar mirror banati hai?

Tumhe chahiye

teen bahut saaf test tubes (dilute NaOH se, phir distilled water se dhoye hue)
Tollens' reagent, teacher ka taaza banaya hua
glucose solution (5 %)
table sugar (sucrose) solution (5 %)
propanone
lagbhag 60 °C ke garam water ka ek beaker

Pehle guess karo

Tumhe kis sample se silver mirror ki ummeed hai?

sucrose solutionglucose solutionpropanone

Teacher reagent banate hain: silver nitrate solution mein NaOH ki ek boond se brown precipitate banta hai, aur dilute ammonia boond-boond karke tab tak daalte hain jab tak woh bas ghul na jaaye.
Har labelled tube mein 2 mL reagent daalo.
1 mL glucose solution, sucrose solution aur propanone daalo, har tube mein ek.
Tubes ko bina hilaye paanch minute garam water mein khada rakho. Inhe kabhi flame par garam mat karo.
Jo dikhe woh record karo, phir tubes turant teacher ko wapas de do.

Table 8.3Observations

Sample	Kya dikhta hai
Glucose
Sucrose
Propanone

Tumhari entries apne aap save hoti hain.

Example 8.4NCERT Example 8.4 · p. 240

Ek unknown aldehyde ki pehchaan

Compound A, $C_{4} H_{8} O$ , 2,4-DNP reagent ke saath orange precipitate aur Tollens' reagent ke saath silver mirror deta hai, lekin iodine aur sodium hydroxide ke saath koi yellow precipitate nahi deta. A ka Clemmensen reduction 2-methylpropane deta hai. A ko pehchano. Phir dilute NaOH ke saath A jo product deta hai woh likho, aur samjhao ki zyaadatar aldols ki tarah woh product garam karne par water kyun nahi khota.

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

Reactions due to α-hydrogen

Carbonyl group ke bagal wala carbon α-carbon hai, aur us par lage hydrogens α-hydrogens hain. Yeh normal C–H hydrogens se kahin zyada acidic hote hain: propanone ka pKa lagbhag 19 hai, jabki ethane ka lagbhag 50. Do effects saath milte hain. Electron-withdrawing C=O group C–H bond ko kamzor karta hai, aur peeche bacha anion, ek enolate ion, resonance se stable hota hai jo negative charge ko electronegative oxygen par le jaata hai.

Enolate ion aur uske do resonance forms

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

Aldol reaction

Yahan ek hi carbonyl compound dono role nibhata hai. Dilute alkali uske thode se hisse ko enolate bana deta hai; enolate ka carbon ek bina badle molecule ke C=O par attack karta hai, aur protonation addition poora karta hai (Fig. 8.9). Naya bond C–C hai, jo is reaction ko synthesis ke sabse useful reactions mein se ek banata hai. Product mein C=O se β wale carbon par ek –OH hota hai. Aldehyde se yeh β-hydroxy aldehyde hai, jise aldol kehte hain kyunki yeh aldehyde bhi hai aur alcohol bhi; ketone se yeh β-hydroxy ketone, ya ketol, hai. Kam se kam ek α-hydrogen wala koi bhi aldehyde ya ketone is tarah react kar sakta hai.

4/4Garam karne se water nikalta hai: 2-ethylhex-2-enal, ek α,β-unsaturated aldehyde.

Fig. 8.9Butanal: enolate, doosre molecule par attack, aldol, phir water ka nikalna.NCERT p. 241

Row 1 butanal ko CH₃–CH₂–CH₂–CHO ki tarah dikhata hai, CHO ke bagal wale CH₂ par gola bana hai aur label alpha hai; OH minus removes alpha-H plus label wala arrow row 2 tak le jaata hai, enolate CH₃–CH₂–CH⁻–CHO, jiska charge oxygen ke saath share hota hai. Step 2 ek doosra butanal, C₃H₇CHO, jodta hai aur negative carbon se uske C=O carbon tak ek curved arrow. Step 3 aldol dikhata hai, CH₃–CH₂–CH₂–CH(OH)–CH(C₂H₅)–CHO, 2-ethyl-3-hydroxyhexanal, jismein naya C–C bond mota bana hai. Step 4 garam karne par dehydration dikhata hai: CH₃CH₂CH₂–CH=C(C₂H₅)–CHO, 2-ethylhex-2-enal.

Aldols aasani se dehydrate hote hain, khaaskar garam karne par: β-OH aur ek α-H water ke roop mein nikal jaate hain, aur naya C=C, C=O ke saath conjugated ho jaata hai, jisse α,β-unsaturated aldehyde ya ketone milta hai. Chemists addition-plus-dehydration ko aldol condensation kehte hain, chahe starting compound aldehyde ho ya ketone. Butanal wala reaction bahut bade scale par chalaya jaata hai: 2-ethylhex-2-enal ko hydrogenate karne se 2-ethylhexan-1-ol milta hai, jo plasticisers ka raw material hai.

Definition

Aldol

Ek β-hydroxy aldehyde (ya ketone se, β-hydroxy ketone) jo tab banta hai jab ek carbonyl compound ka enolate doosre ke C=O par add hota hai.

ExampleDilute NaOH ke saath do butanal molecules 2-ethyl-3-hydroxyhexanal dete hain.

Cross aldol reaction

Do alag carbonyl compounds milao jin dono mein α-hydrogens hon, to har ek enolate (nucleophile) bhi ban sakta hai aur acceptor (electrophile) bhi. Chaar aldols bante hain aur product ek mixture hota hai. Jaise ethanal aur butanal se milte hain:

Table 8.4Ethanal aur butanal se bane chaar aldols

Enolate kisse	Kis par add	Bana aldol
ethanal	ethanal	3-hydroxybutanal
butanal	butanal	2-ethyl-3-hydroxyhexanal
ethanal	butanal	3-hydroxyhexanal
butanal	ethanal	2-ethyl-3-hydroxybutanal

Mixture wali problem tab khatam ho jaati hai jab ek partner mein α-hydrogen na ho, taaki woh sirf accept kar sake. Aromatic aldehydes classic acceptors hain: propanone aur dilute alkali ke saath benzaldehyde dehydration ke baad 4-phenylbut-3-en-2-one deta hai. Aromatic aldehyde ke saath kisi aldehyde ya ketone ke cross aldol condensations ko Claisen–Schmidt condensations bhi kehte hain.

Benzaldehyde aur propanone (Ph = C₆H₅)

\begin{aligned} P h C H O \\ + C H_{3} C O C H_{3} \\ \overset{O H^{-}}{\to} \\ P h C H = C H C O C H_{3} \\ + H_{2} O \end{aligned}

Doosre reactions

Cannizzaro reaction. Jis aldehyde mein α-hydrogen nahi hota woh enolate nahi bana sakta, isliye dilute alkali ke paas kaam karne ko kuch nahi hota. Lekin use concentrated alkali ke saath garam karo, to molecules ke pairs ek hydride ion ka len-den karte hain: ek oxidise hokar carboxylate salt banta hai, aur doosra reduce hokar alcohol. Yeh self oxidation–reduction (ek disproportionation) Cannizzaro reaction hai. Hydroxide ek C=O group par add hota hai, aur phir tetrahedral anion ek hydride ion seedha doosre molecule ke carbonyl carbon ko de deta hai (Fig. 8.10).

4/4Ek proton transfer se carboxylate aur alcohol milte hain.

Fig. 8.10Ek molecule doosre ko hydride deta hai: ek oxidise hota hai, doosra reduce.NCERT p. 242

Do aldehyde molecules R–CHO, jismein R = (CH₃)₃C aur koi alpha hydrogen nahi, aamne-saamne hain. Step 1: OH minus left molecule ke carbonyl carbon par attack karta hai. Step 2: left carbon ab tetrahedral hai jis par O minus aur OH hain; ek curved arrow uske hydrogen ko, hydride ion ke roop mein, right molecule ke carbonyl carbon tak le jaata hai. Step 3: left molecule carboxylic acid R–COOH ban gaya hai, jise oxidised ke roop mein shade kiya gaya hai, aur right wala alkoxide R–CH₂–O minus, jise reduced ke roop mein shade kiya gaya hai. Step 4: ek proton acid se alkoxide par jaata hai, aur R–COO minus aur R–CH₂OH milte hain.

2,2-Dimethylpropanal: alcohol + carboxylate

\begin{aligned} 2 (C H_{3})_{3} C C H O \\ + N a O H \overset{h e a t}{\to} \\ (C H_{3})_{3} C C H_{2} O H \\ + (C H_{3})_{3} C C O O N a \end{aligned}

Methanal, benzaldehyde aur 2,2-dimethylpropanal sab is tarah react karte hain. Crossed Cannizzaro reaction mein methanal ko aise doosre aldehyde ke saath milate hain jismein α-hydrogens na hon. Methanal, jo zyada reactive hai, oxidise hota hai (methanoate tak), isliye doosra aldehyde reduce hota hai: 4-methylbenzaldehyde achhi yield mein (4-methylphenyl)methanol deta hai.

Electrophilic substitution. Aromatic aldehydes aur ketones mein –CHO ya –COR group ring se electron density kheenchta hai, induction se bhi aur resonance se bhi. Ring electrophiles ke saath dheere react karti hai (group deactivating hai), aur ortho aur para positions sabse zyada electron density khote hain, isliye substitution mainly meta position par hota hai. Thande mein mixed acid se acetophenone ka nitration zyaadatar 3-nitroacetophenone deta hai.

Practice · 2 questions

Practice 8.4–8.5: answers ke saath

1
Quick answerMediumNCERT Intext Question 8.4
Har set ko nucleophilic addition ki taraf reactivity ke badhte order mein lagao.
1. (a)
  methanal, butanone, ethanal, 3-methylbutan-2-one
  ethanal
  butanone
  3-methylbutan-2-one
  methanal
  Answer dekho
  Answer
  3-methylbutan-2-one
  butanone
  ethanal
  methanal
  Ketones aldehydes se dheeme hain, aur bade isopropyl group wala ketone sabse dheema hai; methanal, jismein koi alkyl group nahi, sabse tez hai.
2. (b)
  benzaldehyde, 3-nitrobenzaldehyde, benzophenone, 4-methoxybenzaldehyde
  benzophenone
  3-nitrobenzaldehyde
  benzaldehyde
  4-methoxybenzaldehyde
  Answer dekho
  Answer
  benzophenone
  4-methoxybenzaldehyde
  benzaldehyde
  3-nitrobenzaldehyde
  Benzophenone ek ketone hai jismein do rings conjugation mein hain aur crowding bahut hai. Para-methoxy group ring mein aur C=O par electrons bhejta hai (+R), isliye reactivity kam karta hai; meta-nitro group electrons kheenchta hai (−I) aur use badhata hai.
2
Short answerMediumNCERT Intext Question 8.5
Har reaction ka organic product predict karo.
1. Hydroxylamine (weak acid) ke saath propanone
  Solution dikhao
  $(C H_{3})_{2} C = N O H$ , propanone oxime.
2. Phenylhydrazine ke saath butanal
  Solution dikhao
  $C H_{3} C H_{2} C H_{2} C H = N$ – $N H C_{6} H_{5}$ , butanal phenylhydrazone.
3. Semicarbazide (weak acid) ke saath cyclohexanone
  Solution dikhao
  Ring ka C=O, C=N– $N H C O N H_{2}$ ban jaata hai: cyclohexanone semicarbazone.
4. Methylamine (weak acid) ke saath benzaldehyde
  Solution dikhao
  $C_{6} H_{5} C H = N C H_{3}$ , ek Schiff base (substituted imine).

8.5 Uses of Aldehydes and Ketones

Propanone aur butanone paints, varnishes, lacquers, adhesives aur nail polish ke roz ke solvents hain. Kai carbonyl compounds apni smell ya taste ke liye keemti hain: flavours, perfumes aur dyes mein benzaldehyde (bitter almond), aur medicines, foods aur fragrances mein camphor, citral, muscone aur vanillin. Methanal formalin ke roop mein bikta hai, water mein lagbhag 40 % methanal, jise labs specimens preserve karne ke liye use karti hain. Lekin zyaadatar methanal resins mein jaata hai: phenol ke saath Bakelite-type plastics, aur urea–methanal aur melamine glues jo plywood aur particle board ko jodte hain. Ethanal ethanoic acid, ethyl ethanoate aur doosre chemicals banane mein ek intermediate hai.

8.6 Nomenclature and Structure of Carboxyl Group

Kitchen ke khatte tastes zyaadatar carboxylic acids se hain: vinegar mein ethanoic acid, nimbu mein citric acid, imli mein tartaric acid aur dahi mein lactic acid. Fats aur oils mainly lambe, unbranched fatty acids ke glycerol esters hain, jinmein lagbhag 12 se 18 carbon atoms hote hain. In sab mein carboxyl group, –COOH, common hai, yaani carbonyl carbon par ek hydroxyl group; iska naam dono ko milata hai (carbonyl + hydroxyl). Jin compounds mein yeh hota hai woh carboxylic acids hain. Molecule ka baaki hissa alkyl chain (aliphatic acids, RCOOH) ya aromatic ring (aromatic acids, ArCOOH) ho sakta hai, aur –OH ko replace karne se Fig. 8.1 ke acid derivatives milte hain.

Definition

Carboxylic acid

Carboxyl group, –COOH, wala organic compound, yaani carbonyl carbon se juda ek hydroxyl group.

ExampleEthanoic acid, $C H_{3} C O O H$ , vinegar ka acid.

8.6.1 Nomenclature

Kai acids ke naam unke formulas likhe jaane se bahut pehle rakhe gaye the, us plant ya animal product ke naam par jisse woh mile, isliye unke common names (-ic acid par khatam hone wale) chhote-chhote history lessons hain. Lactic acid khatte doodh se aata hai (Latin lac, yaani doodh), citric acid citrus fruits se, malic acid apples (malum) se aur oxalic acid wood sorrel (Oxalis) se.

IUPAC rules aldehydes waale rules par hi bane hain:

Parent chain: woh sabse lambi chain jismein –COOH carbon shaamil ho. Woh carbon C1 hai.
Ending: alkane naam ke last -e ko -oic acid se replace karo, to ethane se ethanoic acid banta hai.
Chain ke dono ends par do –COOH groups: poora alkane naam rakho aur -dioic acid jodo: $H O O C (C H_{2})_{4} C O O H$ hexanedioic acid hai.
Ring par –COOH, ya do se zyada –COOH groups: suffix -carboxylic acid use karo, aur COOH carbons ko parent mein mat gino. Examples hain cyclohexanecarboxylic acid aur propane-1,2,3-tricarboxylic acid, jo citric acid ka skeleton hai.
Benzene ring: $C_{6} H_{5} C O O H$ benzoic acid hai (systematically benzenecarboxylic acid), aur iske derivatives ke naam substituted benzoic acids ki tarah rakhe jaate hain.

Table 8.5Kuch carboxylic acids ke common aur IUPAC namesNCERT Table 8.3 · p. 244

Formula	Naam
$C H_{3} (C H_{2})_{3} C O O H$	valeric acid (pentanoic acid)
$C H_{3} (C H_{2})_{4} C O O H$	caproic acid (hexanoic acid)
$C H_{3} C H (O H) C O O H$	lactic acid (2-hydroxypropanoic acid)
$C H_{2} = C H C O O H$	acrylic acid (propenoic acid)
$H O O C C H_{2} C H (O H) C O O H$	malic acid (2-hydroxybutanedioic acid)
$C H_{3} (C H_{2})_{14} C O O H$	palmitic acid (hexadecanoic acid)
$C H_{3} (C H_{2})_{16} C O O H$	stearic acid (octadecanoic acid)
$C_{6} H_{5} C H = C H C O O H$	cinnamic acid (3-phenylprop-2-enoic acid)
$H O C_{6} H_{4} C O O H$ (ortho)	salicylic acid (2-hydroxybenzoic acid)

8.6.2 Structure of Carboxyl Group

Carboxyl carbon carbonyl carbon ki tarah sp² hybridised hai, isliye woh, uske do oxygens aur usse juda atom ek plane mein hote hain aur bond angles lagbhag 120° hote hain. Fark hai bagal wala –OH oxygen. Uska ek lone pair C=O π bond ke saath overlap kar sakta hai, jisse ek resonance form banta hai jismein carbonyl oxygen par negative charge aur –OH oxygen par positive charge hota hai (Fig. 8.11). Electron density carbonyl carbon ki taraf behti hai, isliye woh aldehyde ya ketone ke carbon se kam electrophilic hota hai. Isi wajah se carboxylic acids aldehydes aur ketones wale typical nucleophilic additions nahi dete: na cyanohydrins, na oximes, na hydrogensulphite adducts.

2/3Ek OH lone pair C=O mein delocalise hota hai, jisse doosra resonance form banta hai.

Fig. 8.11OH ka lone pair carbonyl carbon ko electrons deta hai, isliye uska δ+ ketone se chhota hota hai.NCERT p. 245

Step 1 R–C(=O)–O–H ko ek flat group ki tarah banata hai, do 120 degree angles mark hain aur note hai: all atoms in one plane. Step 2 OH oxygen par do lone-pair dots jodta hai, unse C–O bond mein jaata ek curved arrow aur C=O bond se upar wale oxygen par jaata ek aur arrow, aur ek double-headed resonance arrow ke baad doosra form R–C(–O minus)=O plus–H. Step 3 delta plus on carbonyl C label wale do bars jodta hai: ketone ke liye lamba bar aur acid ke liye chhota bar.

8.7 Methods of Preparation of Carboxylic Acids

Carboxylic acids tak chhe common routes jaate hain. Inmein se do, nitriles se aur Grignard reagents se, chain mein ek carbon atom bhi jodte hain.

1. Primary alcohols aur aldehydes se. Koi bhi strong oxidant primary alcohol ko aldehyde se hote hue acid tak le jaata hai. Common choices hain $K M n O_{4}$ (yeh solution acidic, neutral ya alkaline, kuch bhi ho, kaam karta hai), dilute sulphuric acid ke saath $K_{2} C r_{2} O_{7}$ , aur aqueous sulphuric acid mein $C r O_{3}$ , jise Jones reagent kehte hain. Alkaline $K M n O_{4}$ ke saath product potassium salt hota hai, isliye acid baad mein dilute acid se free kiya jaata hai. Aldehydes to mild reagents se bhi oxidise ho jaate hain (oxidation wala section).

Hexan-1-ol se hexanoic acid (Jones reagent)

\begin{aligned} C H_{3} (C H_{2})_{4} C H_{2} O H \\ \overset{C r O_{3}, H_{2} S O_{4}}{\to} \\ C H_{3} (C H_{2})_{4} C O O H \end{aligned}

2. Alkylbenzenes se. Benzene ring par side chain par uske benzylic carbon par attack hota hai, yaani jo ring se juda hai, bas shart yeh hai ki us carbon par kam se kam ek hydrogen ho. Garam alkaline ya acidic $K M n O_{4}$ , ya chromic acid, tab tak nahi rukta jab tak chain ke baaki saare carbons chale na jaayein. Methyl, ethyl ya butyl group, sab aakhir mein ring par ek –COOH ban jaate hain. Tert-butyl group, jiske benzylic carbon par koi hydrogen nahi, bach jaata hai (Fig. 8.12).

3/3Acid potassium salt ko benzoic acid bana deta hai.

Fig. 8.12Side-chain oxidation ke liye benzylic hydrogen chahiye; aisi har chain ek –COOH ban jaati hai.NCERT p. 246

Chaar alkylbenzenes ki list hai, jismein benzylic carbon rang mein hai aur note hai ki us par kitne benzylic hydrogens hain: ethylbenzene (2), isopropylbenzene (1), butylbenzene (2) aur tert-butylbenzene (koi nahi). Step 2, heading hot KMnO₄, KOH, arrows banata hai: pehle teen C₆H₅COO⁻ K⁺ dete hain, jabki tert-butylbenzene par cross laga hai aur no change mark hai, note ke saath: chain cut back to one carbon. Step 3, heading then H₃O⁺, teeno salts ko C₆H₅COOH, benzoic acid, bana deta hai.

3. Nitriles aur amides se. C≡N group par water do stages mein add hota hai. Naram conditions amide deti hain, jise alag kiya ja sakta hai; aqueous acid ke saath (ya alkali ke saath aur phir acidification) zyada der garam karne par amide bhi hydrolyse ho jaata hai, ammonia (ya ammonium salt) nikalta hai aur acid bach jaata hai.

Propanenitrile se propanoic acid

\begin{aligned} C_{2} H_{5} C \equiv N \\ \overset{H_{2} O, H^{+}}{\to} \\ C_{2} H_{5} C O N H_{2} \\ \to_{h e a t}^{H_{2} O, H^{+}} \\ C_{2} H_{5} C O O H \\ + N H_{4}^{+} \end{aligned}

4. Grignard reagents se. Grignard reagent carbon dioxide ke C=O group par add hota hai (gas bubble karke, ya crushed dry ice par daalkar), aur magnesium carboxylate banta hai. Phir dilute acid acid ko free karta hai.

2-bromopropane se 2-Methylpropanoic acid

\begin{aligned} (C H_{3})_{2} C H M g B r \\ + C O_{2} \overset{e t h e r}{\to} \\ (C H_{3})_{2} C H C O O M g B r \\ \overset{H_{3} O^{+}}{\to} \\ (C H_{3})_{2} C H C O O H \end{aligned}

Carbons gino: routes 3 aur 4 mein –COOH carbon bahar se aata hai, cyanide se ya carbon dioxide se. Alkyl halide KCN ke saath nitrile aur Mg ke saath Grignard reagent deta hai (Unit 6), isliye dono mein se koi bhi route R–X ko ek zyada carbon atom wale acid mein badal deta hai, ek step jise chemists ascending the series kehte hain.

5. Acyl halides aur anhydrides se. Acyl chlorides nam hawa mein dhuaan dete hain kyunki woh water se itni aasani se react karte hain, aur acid aur HCl dete hain; aqueous alkali ke saath product carboxylate hota hai, jisse dilute acid acid ko free karta hai. Anhydrides zyada shaant hote hain: water unhe dheere-dheere kholkar do acid molecules bana deta hai (agar anhydride mixed ho to do alag acids).

Acyl chloride aur anhydride ka hydrolysis

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

6. Esters se. Acid hydrolysis (dilute $H_{2} S O_{4}$ ke saath water) ek equilibrium hai jo seedha acid aur alcohol deta hai. Alkaline hydrolysis, saponification, poora complete hota hai aur acid ka salt deta hai, jisse dilute acid free acid nikaalta hai.

Ethyl ethanoate ka saponification

\begin{aligned} C H_{3} C O O C_{2} H_{5} \\ + N a O H \overset{h e a t}{\to} \\ C H_{3} C O O N a \\ + C_{2} H_{5} O H \\ C H_{3} C O O N a \overset{H_{3} O^{+}}{\to} \\ C H_{3} C O O H \end{aligned}

Example 8.5NCERT Example 8.5 · p. 247

Acids tak routes plan karna

Har change ke liye reagents likho: (a) propan-1-ol se propanoic acid; (b) 1-bromopropane se butanoic acid; (c) 4-bromotoluene se 4-bromobenzoic acid; (d) cyclopentene se pentanedioic acid; (e) pentanal se pentanoic acid; (f) 1,3-dimethylbenzene se benzene-1,3-dicarboxylic acid.

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

Practice · 1 question

Practice 8.7: answers ke saath

1
Short answerMediumNCERT Intext Question 8.7
Dikhao ki har compound ko benzoic acid mein kaise badla ja sakta hai.
1. Isopropylbenzene (cumene)
  Solution dikhao
  Garam $K M n O_{4}$ /KOH side chain ko kaat kar – $C O O^{-}$ bana deta hai (benzylic carbon par ek H hai); phir $H_{3} O^{+}$ se $C_{6} H_{5} C O O H$ milta hai.
2. Benzonitrile
  Solution dikhao
  Aqueous acid ke saath garam karo: $C_{6} H_{5} C N$ → $C_{6} H_{5} C O N H_{2}$ → $C_{6} H_{5} C O O H$ + $N H_{4}^{+}$ .
3. Methyl benzoate
  Solution dikhao
  NaOH(aq) ke saath garam karke hydrolyse karo, jisse sodium benzoate aur methanol milte hain, phir dilute HCl se acidify karo.
4. Iodobenzene
  Solution dikhao
  Dry ether mein Mg se $C_{6} H_{5} M g I$ banta hai; dry ice ( $C O_{2}$ ) daalo, phir $H_{3} O^{+}$ .

8.8 Physical Properties

Chhote straight-chain acids, lagbhag $C_{9}$ tak, 298 K par liquids hote hain. Kai ki smell tez ya buri hoti hai: butanoic acid kharab (rancid) butter ki smell hai, aur hexanoic (caproic) acid ka naam bakri (Latin caper) se aaya hai. Lambi chain wale acids naram, waxy solids hote hain jinki smell lagbhag nahi hoti, kyunki unke bahut kam molecules hawa mein nikal paate hain.

Fig. 8.5 ka aakhri step phir dekho: butanoic acid pentan-1-ol se 26 K upar boil hota hai, jabki dono ka M = 88 g/mol hai. Alcohol molecules badalti chains mein single hydrogen bonds se jude rehte hain. –COOH group ek partner ke saath ek saath do hydrogen bonds bana sakta hai, isliye acid molecules aamne-saamne cyclic dimers ke roop mein jode bana lete hain (Fig. 8.13). Yeh jode mazboot hote hain. Boiling point ke paas vapour-density measurements, aur benzene mein naape gaye molar masses, formula mass ke lagbhag double aate hain: dimers boiling mein bhi tike rehte hain, aur aise solvent mein ghulne par bhi jo hydrogen bond nahi bana sakta.

2/3Do hydrogen bonds ek jode ko saath rakhte hain, vapour mein bhi.

Fig. 8.13Ethanoic acid do hydrogen bonds se jode banata hai aur water se bhi hydrogen bond banata hai.NCERT p. 249

Step 1 ek ethanoic acid molecule, CH₃–C(=O)–O–H, dikhata hai, dono oxygens par delta minus aur hydroxyl hydrogen par delta plus. Step 2 pehle ke saamne ek doosra molecule jodta hai: har ek ka C=O oxygen doosre ke O–H hydrogen se ek dashed hydrogen bond se juda hai, jisse ek eight-membered ring band hoti hai, label: two H-bonds hold a pair. Step 3 partner ko hata deta hai aur acid se hydrogen-bonded teen water molecules dikhata hai, ek-ek dono oxygens se aur ek O–H hydrogen se, label: H-bonds to water.

Water ke saath –COOH group hydrogen bonds dene mein dildaar hai, isliye methanoic se butanoic tak ke acids usmein poori tarah mix ho jaate hain. Har extra $C H_{2}$ molecule ko zyada oil jaisa banata hai: hexanoic acid sirf lagbhag 1 g per 100 mL tak ghulta hai, aur fatty acids lagbhag bilkul nahi, aur yahi ek wajah hai ki grease saade water se nahi dhulti. Benzoic acid temperature ka effect dikhata hai: 100 mL thande water mein 0.4 g se kam ghulta hai lekin boiling water mein 5 g se zyada, isliye water se recrystallisation karke ise aasani se purify kiya jaata hai.

Quick check

2 mein se 1

Boiling point ke paas ethanoic acid ki vapour ki density

C H_{3} C O O H

se expected value ki lagbhag double hoti hai. Kyun?

Yeh bhaari products mein decompose ho jaata haiVapour mein iske molecules ionised hote hainVapour mein ghula hua water hota haiIske molecules hydrogen-bonded dimers ke roop mein jode mein hote hain

Answer dekho

Answer (D) Iske molecules hydrogen-bonded dimers ke roop mein jode mein hote hain

Do hydrogen bonds se jude do molecules lagbhag double molar mass wale ek particle ki tarah chalte hain. Vapour mein ions nahi bante, aur koi bhaari compound nahi banta.

8.9 Chemical Reactions

Carboxylic acids ke reactions chaar groups mein baante jaate hain. Inhe is hisaab se baanta gaya hai ki kaunsa bond tootta hai ya molecule ka kaunsa hissa react karta hai: O–H bond (acidity), C–OH bond (–OH replace hota hai), poora –COOH group, aur hydrocarbon part.

8.9.1 Reactions Involving Cleavage of O–H Bond

Metals aur bases ke saath reactions. Ghatti strength wale teen bases tumhare jaane-pehchaane O–H compounds ko alag karte hain. Sodium metal alcohols, phenols aur carboxylic acids, sabse hydrogen nikaalta hai. Sodium hydroxide phenols aur carboxylic acids ke saath salts banata hai, lekin alcohols ke saath khaas nahi. Asli filter sodium hydrogencarbonate hai: sirf carbonic acid se strong acids, jo practically carboxylic acids hi hain, ise carbon dioxide mein badalte hain. Isliye $N a H C O_{3}$ solution ke saath tez fizz –COOH group ka laboratory test hai.

Sodium ke saath aur sodium hydroxide ke saath

\begin{aligned} 2 C H_{3} C O O H + 2 N a \\ \overset{}{\to} 2 C H_{3} C O O N a \\ + H_{2} ↑ \\ C H_{3} C O O H + N a O H \\ \overset{}{\to} C H_{3} C O O N a \\ + H_{2} O \end{aligned}

Hydrogencarbonate test

\begin{aligned} C H_{3} C O O H \\ + N a H C O_{3} \\ \overset{}{\to} C H_{3} C O O N a \\ + H_{2} O + C O_{2} ↑ \end{aligned}

Try karke dekho

Kitchen ke kaunse liquids carboxylic acids hain?

Tumhe chahiye

baking soda (sodium hydrogencarbonate)
white vinegar
nimbu ka ras (lemon juice)
water mein ek chutki citric acid (nimbu sat)
ek antiseptic liquid jiske label par chloroxylenol (ek phenol) likha ho, das guna dilute kiya hua
chaar chhote glass aur ek teaspoon

Pehle guess karo

Tumhare hisaab se kaunsa liquid baking soda ke saath fizz nahi karega?

vinegarlemon juicedilute kiya hua antiseptic

Chaar labelled glasses mein se har ek mein aadha teaspoon baking soda daalo.
Do tablespoon vinegar, lemon juice, citric acid solution aur dilute antiseptic daalo, har glass mein ek.
Aadhe minute tak har glass mein bubbles dekho aur table mein haan ya nahi likho.
Kuch bhi chakhna mat; baad mein haath aur glasses dho lo.

Table 8.6Observations

Liquid	Fizz hua?
Vinegar
Lemon juice
Citric acid
Antiseptic

Tumhari entries apne aap save hoti hain.

Water mein carboxylic acid apna O–H proton ek water molecule ko de deta hai, jisse hydronium ion aur resonance-stabilised carboxylate ion bante hain. Is reaction ka equilibrium constant acid ki strength naapta hai.

Water mein ionisation

\begin{aligned} R C O O H + H_{2} O \overset{}{⇌} \\ R C O O^{-} + H_{3} O^{+} \end{aligned}

Acid dissociation constant

K_{a} = \frac{[A^{-}] [H_{3} O^{+}]}{[H A]}

(8.1)

jahan

$H A$: acid, RCOOH
$A^{-}$: uska carboxylate ion, $R C O O^{-}$

Water solvent hai, isliye uska concentration lagbhag nahi badalta aur use constant mein mila diya jaata hai: $K_{a}$ equilibrium constant ko $[H_{2} O]$ se multiply karke milta hai. Kyunki $K_{a}$ values das ki kai powers tak failti hain, chemists usually iski jagah pKa batate hain:

pKa ki definition

p K_{a} = - \log K_{a}

(8.2)

Definition

pKa

Acid dissociation constant ka negative logarithm, $p K_{a} = - \log K_{a}$ ; pKa jitna chhota, acid utna strong.

ExampleEthanoic acid: $K_{a} = 1.7 \times 10^{- 5}$ , pKa 4.76.

Chhote pKa ka matlab bada $K_{a}$ aur strong acid, aur pKa ki ek unit das guna ka fark hai. Rough scale par, 1 se kam pKa strong acid hai, 1–5 moderately strong, 5–15 weak aur 15 se upar kuch bhi very weak. Ethanoic acid (4.76) aur benzoic acid (4.20) moderately strong band mein hain. Sabse strong carboxylic acids, jaise trifluoroethanoic acid, ke pKa values zero ke paas hain, aur mineral acids isse bhi kahin zyada strong hain (HCl, lagbhag −7).

Table 8.725 °C par water mein pKa values

Acid	pKa
trichloroethanoic acid, $C l_{3} C C O O H$	0.66
chloroethanoic acid, $C l C H_{2} C O O H$	2.87
methanoic acid, $H C O O H$	3.75
benzoic acid, $C_{6} H_{5} C O O H$	4.20
ethanoic acid, $C H_{3} C O O H$	4.76
propanoic acid, $C H_{3} C H_{2} C O O H$	4.87
carbonic acid, $H_{2} C O_{3}$	6.35
phenol, $C_{6} H_{5} O H$	10.0
ethanol, $C_{2} H_{5} O H$	lagbhag 16

Carboxylic acids mineral acids se kahin weak hain lekin phenols aur alcohols se kahin strong. Phenol se strong kyun, jabki phenoxide ion ke carboxylate ion se zyada resonance structures hain? Matter karti hai structures ki quality, unki ginti nahi (Fig. 8.14). Carboxylate ion ke do resonance structures bilkul same hain, isliye dono barabar contribute karte hain, aur dono mein negative charge oxygen atom par hai. Hybrid mein har oxygen par aadha charge hota hai, aur dono C–O bonds ki length same hoti hai.

Phenoxide mein sirf ek structure mein charge oxygen par hai. Baaki use ring ke carbon atoms par rakhte hain, jo kam electronegative hain aur negative charge achhe se nahi sambhaal paate, isliye woh structures kam contribute karte hain. Isliye phenoxide par charge kam effectively failta hai, ion kam stable hota hai, aur phenol apna proton kam aasani se chhodta hai.

4/4Phenoxide mein charge ka kuch hissa kam electronegative ring carbons par hota hai.

Fig. 8.14Carboxylate apna charge do oxygens mein barabar baant deta hai; phenoxide uska kuch hissa carbon par dhakel deta hai.NCERT p. 250

Step 1 ethanoic acid dikhata hai jismein 121 pm ka C=O bond aur 136 pm ka C–OH bond hai. Step 2 ethanoate ion ko double-headed arrow se jude do resonance forms ki tarah dikhata hai, ek mein negative charge neeche wale oxygen par aur doosre mein upar wale oxygen par, note: equal in energy. Step 3 hybrid dikhata hai: har C–O bond ek solid aur ek dashed line se bana hai, dono 126 pm, har oxygen par gola aur label minus one half. Step 4 uske bagal mein phenoxide ion jodta hai: O minus wali benzene ring, oxygen par gola aur teen ring carbons (do ortho, ek para) par dashed gole, label one O plus three ring C.

Substituents ka effect. Acid ko uske anion se parkho. Jo group – $C O O^{-}$ se electron density door kheenchta hai woh negative charge ko failata hai, aur isliye anion, aur acid, ko strong banata hai. Yeh σ bonds ke through (−I effect) ya π bonds ke through (−R) kheench sakta hai; – $N O_{2}$ , –CN aur halogens yahi karte hain. Jo group – $C O O^{-}$ ki taraf electron density dhakelta hai, jaise alkyl group (+I), woh charge ko jama karta hai aur acid weak hota hai. Teen patterns yaad rakhne layak hain, aur har ek ko tum Fig. 8.15 mein explore kar sakte ho:

Zyada kheench, zyada strong acid. $X C H_{2} C O O H$ mein ek group X ke liye acid strength is order mein badhti hai: $C H_{3}$ < H < $C_{6} H_{5}$ < I < Br < Cl < F < CN < $N O_{2}$ (pKa 4.87 se gir kar 1.68 tak).
Zyada groups, zyada strong acid. Har chlorine apna kheench jodta hai: ethanoic acid 4.76, chloroethanoic 2.87, dichloroethanoic 1.35, trichloroethanoic 0.66.
Jitna paas, utna strong. Inductive effect chain ke saath jaldi khatam ho jaata hai: 2-chlorobutanoic acid ka pKa 2.86 hai, 3-chloro acid ka 4.05 aur 4-chloro acid ka 4.52, jo khud butanoic acid (4.82) se bas thoda neeche hai.

–COOH se juda carbon. Yahan ek puzzle hai. Benzene ring (ya C=C) aur carboxyl group ke beech resonance ko electrons – $C O O^{-}$ ki taraf dhakelne chahiye aur acid ko weak karna chahiye, phir bhi benzoic acid (4.20) aur propenoic acid (4.25) dono ethanoic acid (4.76) se strong hain. Jawab –COOH se jude carbon atom mein hai. Uske bonding orbital mein jitna zyada s character, carbon electrons ko utna kas kar pakadta hai. sp² carbon (33 % s) sp³ carbon (25 % s) se zyada electronegative hai, isliye woh carboxylate se density door kheenchta hai. sp carbon (50 % s) yeh aur bhi zyada karta hai, isi wajah se propynoic acid ka pKa 1.84 hai. Phir benzoic acid ki ring par lage groups waisa hi kaam karte hain jaisa tum expect karoge: 4-chlorobenzoic acid (3.98) benzoic acid se strong hai, aur 4-methylbenzoic acid (4.37) weak.

InteractiveAcid-strength explorer

Paanch buttons acids ki ek family chunte hain: COOH ke bagal wale carbon par ek group X, ek se teen chlorine atoms, butanoic acid mein alag-alag doori par chlorine, carboxyl group se jude alag carbons (sp3, sp2 aur sp), aur substituted benzoic acids. Neeche ke buttons ek acid chunte hain. Teen readouts uska pKa, uska Ka aur woh ethanoic acid se kitne guna strong ya weak hai, batate hain. 0 se 5.5 tak ka ek pKa scale family ke har acid ko mark karta hai, chuna hua acid highlighted hota hai aur ethanoic acid ek dashed reference line hai, aur ek sentence kaam kar rahe effect ko samjhata hai. Ek doosra scale carboxylic acids ko HCl, carbonic acid, phenol, water aur ethanol ke beech rakhta hai.

Fig. 8.15Acids ki ek family chuno, phir ek acid: panel uska pKa, uska Ka, ethanoic acid se uska comparison, aur wajah dikhata hai.

8.9.2 Reactions Involving Cleavage of C–OH Bond

1. Anhydrides. Acid ko phosphorus pentoxide jaise dehydrating agent ke saath garam karne se do molecules water khokar jud jaate hain, aur acid anhydride milta hai.

Ethanoic anhydride

\begin{aligned} 2 C H_{3} C O O H \to_{h e a t}^{P_{4} O_{10}} \\ (C H_{3} C O)_{2} O + H_{2} O \end{aligned}

2. Esterification. Acid aur alcohol, thode concentrated sulphuric acid ya dry HCl gas ke saath garam karne par, ester aur water dete hain. Reaction reversible hai aur aise equilibrium par ruk jaata hai jahan dono sides kaafi maujood hoti hain, isliye yield badhane ke liye excess alcohol use karte hain ya bante hi water (ya ester) hata dete hain.

Methyl propanoate

\begin{aligned} C H_{3} C H_{2} C O O H \\ + C H_{3} O H \overset{H^{+}}{⇌} \\ C H_{3} C H_{2} C O O C H_{3} \\ + H_{2} O \end{aligned}

Esterification ek nucleophilic acyl substitution hai: acid ka –OH, –OR′ se replace hota hai. Heavy isotope oxygen-18 se bane alcohol ke saath experiments dikhate hain ki alcohol ka oxygen ester mein pahunchta hai, aur water ke roop mein nikalne wala oxygen acid se aata hai. Steps Fig. 8.16 mein dikhaye gaye hain:

Acid catalyst C=O oxygen ko protonate karta hai, jisse carbon kahin zyada electrophilic ho jaata hai.
Alcohol ka oxygen us carbon par attack karta hai, aur ek tetrahedral intermediate banta hai.
Ek proton naye jude oxygen se ek –OH group par chala jaata hai, aur use – $O H_{2}^{+}$ bana deta hai, jo ek achha leaving group hai.
Water nikal jaata hai aur protonated C=O phir se ban jaata hai.
$H^{+}$ nikalne se ester milta hai aur catalyst wapas aa jaata hai.

3/5Ek proton shift hota hai; –OH, – $O H_{2}^{+}$ ban jaata hai.

Fig. 8.16Alcohol ka oxygen ester mein pahunchta hai; acid ka –OH water ke roop mein nikalta hai.NCERT p. 252

Beech mein R–C bana hai aur uske baaki groups badalte rehte hain. Step 1: R–C(=O)–OH, aur H plus C=O oxygen ki taraf aa raha hai. Step 2: oxygen ab double bond par OH plus hai, aur neeche se R′–OH ek curved arrow ke saath carbon par attack karta hai. Step 3: carbon tetrahedral hai, upar OH, neeche OR′ aur right mein ek OH₂ plus group, jise achhe leaving group ke roop mein highlight kiya gaya hai. Step 4: water right ki taraf door chala jaata hai aur upar phir C=OH plus bond hai, neeche OR′. Step 5: H plus upar wale oxygen se nikalta hai, aur ester R–C(=O)–OR′ milta hai.

3. $P C l_{5}$ , $P C l_{3}$ ya $S O C l_{2}$ ke saath. Alcohols ki tarah, –OH ko Cl se badla ja sakta hai, aur acyl chloride milta hai. Teeno reagents mein thionyl chloride chemists ka favourite hai: iske by-products, $S O_{2}$ aur HCl, bas bubble hokar ud jaate hain, jabki phosphorus pentachloride liquid $P O C l_{3}$ chhodta hai aur phosphorus trichloride $H_{3} P O_{3}$ chhodta hai, jinhe product se alag karna padta hai.

Thionyl chloride route

\begin{aligned} R C O O H + S O C l_{2} \\ \overset{}{\to} R C O C l + S O_{2} ↑ \\ + H C l ↑ \end{aligned}

4. Ammonia ke saath. Acid aur ammonia pehle ammonium salt banate hain; phir tez garam karne se water nikal jaata hai aur amide milta hai. Benzene-1,2-dicarboxylic (phthalic) acid jaisa dicarboxylic acid diamide deta hai, jo aur tez garam karne par ammonia kho deta hai aur ek cyclic imide, phthalimide, mein band ho jaata hai.

Propanamide

\begin{aligned} C_{2} H_{5} C O O H + N H_{3} \\ \overset{}{⇌} C_{2} H_{5} C O O N H_{4} \\ \overset{h e a t}{\to} C_{2} H_{5} C O N H_{2} \\ + H_{2} O \end{aligned}

8.9.3 Reactions Involving –COOH Group

1. Reduction. Sirf powerful hydride donors hi –COOH ko reduce karte hain. Sodium borohydride, jo aldehydes aur ketones ke liye itna useful hai, acids ko chhoota bhi nahi; dry ether mein lithium aluminium hydride unhe seedha primary alcohols tak le jaata hai. Diborane, $B_{2} H_{6}$ , yahi kaam zyada selectively karta hai: yeh –COOH group ko jaldi reduce karta hai aur molecule mein kahin aur lage nitro, halo aur ester groups ko zyaadatar ignore karta hai, isliye aksar yahi better choice hota hai.

Benzoic acid se phenylmethanol

\begin{aligned} C_{6} H_{5} C O O H \\ \to_{2 \cdot H_{3} O^{+}}^{1 \cdot L i A l H_{4}} \\ C_{6} H_{5} C H_{2} O H \end{aligned}

2. Decarboxylation. Carboxyl carbon ko poori tarah hataya bhi ja sakta hai. Sodium carboxylate ko soda lime (NaOH aur CaO ka 3 : 1 mixture) ke saath fuse karne se woh sodium carbonate ke roop mein nikal jaata hai aur uski jagah H aa jaata hai. Bana hydrocarbon acid se ek carbon chhota hota hai. Electrolysis alag result deta hai. Kolbe electrolysis (Class XI mein padha) mein sodium ya potassium carboxylate ke concentrated solution ka electrolysis kiya jaata hai. Anode par har carboxylate ion ek electron khota hai aur phir $C O_{2}$ . Peeche bache alkyl radicals jodon mein judte hain, aur alkyl group se double size ka hydrocarbon milta hai.

Sodium propanoate se ethane milta hai

\begin{aligned} C H_{3} C H_{2} C O O N a \\ + N a O H \to_{h e a t}^{C a O} \\ C H_{3} C H_{3} + N a_{2} C O_{3} \end{aligned}

Anode par Kolbe electrolysis

\begin{aligned} 2 C H_{3} C O O^{-} \\ \overset{e l e c t r o l y s i s}{\to} C H_{3} C H_{3} \\ + 2 C O_{2} + 2 e^{-} \end{aligned}

8.9.4 Substitution Reactions in the Hydrocarbon Part

1. α-carbon par halogenation. Kam se kam ek α-hydrogen wale acid ko $C l_{2}$ ya $B r_{2}$ ke saath treat karo, catalyst ke roop mein thoda red phosphorus daalkar, to ek halogen atom ek α-hydrogen ki jagah le leta hai. Yeh Hell–Volhard–Zelinsky (HVZ) reaction hai. Phosphorus $P X_{3}$ banata hai, jo kuch acid ko acyl halide mein badal deta hai; acyl halide acid se kahin aasani se apna enol banata hai, aur enol α-carbon par halogen le leta hai. Aur acid ke saath exchange, aur aakhir mein hydrolysis, α-halo acid dete hain.

2-Bromopropanoic acid

\begin{aligned} C H_{3} C H_{2} C O O H \\ + B r_{2} \overset{r e d P}{\to} \\ C H_{3} C H B r C O O H \\ + H B r \end{aligned}

α-Halo acids useful intermediates hain kyunki halogen aasani se replace ho jaata hai: –OH se, jisse lactic acid jaise 2-hydroxy acids milte hain, ya $- N H_{2}$ se, jisse amino acids milte hain.

2. Ring par substitution. Benzoic acid ko nitrate karo to nitro group mainly meta position par jaata hai: –COOH ring se electrons kheenchta hai, jo electrophilic attack ko slow karta hai aur use ortho aur para positions se door le jaata hai. Friedel–Crafts reactions bilkul fail ho jaate hain, kyunki ring bahut zyada deactivated hai aur Lewis-acid catalyst, $A l C l_{3}$ , ulta carboxyl group se jud jaata hai.

8.10 Uses of Carboxylic Acids

Ethanoic acid vinegar ka acid hai (water mein lagbhag 5 %); pure form mein yeh ek important industrial solvent hai aur ethanoate esters aur vinyl ethanoate polymers jaise plastics ka starting material hai. Methanoic acid rubber latex ko coagulate karne, leather tanning, textiles ki dyeing aur finishing aur electroplating mein use hota hai. Hexanedioic (adipic) acid nylon-6,6 ke do monomers mein se ek hai. Sodium benzoate sauces, squashes aur pickles ko preserve karta hai, aur benzoic acid ke esters perfumes mein khushboo jodte hain. Long-chain fatty acids ke sodium aur potassium salts soaps hain, aur yeh acids detergents ka raw material hain. Citric, lactic aur ethanoic acids foods ko khatta taste dene ke liye khoob use hote hain.

Quick check

2 mein se 1

Har compound ko uske ek main use se match karo.

Left mein koi item tap karo, phir right mein uska match.

Answer dekho

Answer

methanal : resins aur plywood glues
propanone : nail polish remover mein solvent
hexanedioic acid : nylon-6,6 banana
sodium benzoate : food preservative

Methanal phenol–methanal aur urea–methanal resins mein jaata hai; propanone ek common solvent hai; adipic (hexanedioic) acid nylon-6,6 ka monomer hai; sodium benzoate sauces aur squashes ko preserve karta hai.

Revise karne se pehle reaction map use karke check karo ki tum har starting material se uske products tak pahunch sakte ho, aur reagents par khud ko quiz karo.

InteractiveNamed-reaction map

Explore mode mein buttons ek starting family chunte hain: acyl chloride, nitrile, ester, toluene ya benzene, alcohol, alkene ya alkyne, aldehyde ya ketone, aur acid, salt ya Grignard reagent. Phir cards is chapter ke har us reaction ki list dete hain jo wahan se shuru hota hai, har card mein change, reagent, reaction ka naam (agar hai) aur ek chhota tip hota hai. Quiz me mode mein RCOCl se RCHO jaisa ek change teen possible reagents ke saath dikhaya jaata hai; pehli galat choice hint ke saath dhundhli ho jaati hai, doosri galat choice answer dikha deti hai, aur ek running score rakha jaata hai.

Fig. 8.17Har family se shuru hone wale reactions explore karo, ya Quiz me par switch karke diye gaye change ke liye reagent chuno.

Recap

Summary aur key points

Aldehydes (RCHO), ketones (RCOR′) aur carboxylic acids (RCOOH) sab mein C=O hota hai; carbonyl carbon par aur kya laga hai, yahi family decide karta hai (Section 8.1).
IUPAC names -al, -one aur -oic acid par khatam hote hain; common names functional group ke bagal wale carbon se Greek letters (α, β, …) use karte hain (Section 8.1.1, Section 8.6.1).
Carbonyl carbon sp² aur flat hai; C=O bond polar hai, isliye carbon electrophilic aur oxygen nucleophilic hai (Section 8.1.2).
Aldehydes aur ketones alcohols, ozonolysis aur alkyne hydration se milte hain; aldehydes Rosenmund, Stephen, DIBAL-H, Etard aur Gattermann–Koch reactions se bhi; ketones dialkylcadmium, nitrile + RMgX aur Friedel–Crafts acylation se (Section 8.2).
Dipole–dipole forces ki wajah se aldehydes aur ketones hydrocarbons aur ethers se upar lekin alcohols se neeche boil hote hain; chhote waale water mein mix ho jaate hain (Section 8.3).
Nucleophiles C=O par add hote hain: HCN, $N a H S O_{3}$ , RMgX, alcohols (hemiacetals, acetals, ketals) aur $H_{2} N$ –Z (oximes, hydrazones, semicarbazones). Steric aur electronic wajahon se aldehydes ketones se tez react karte hain (nucleophilic addition).
C=O, $N a B H_{4}$ ya $L i A l H_{4}$ se CH–OH tak reduce hota hai, aur Clemmensen (acid) ya Wolff–Kishner (base) reduction se $C H_{2}$ tak (reduction).
Aldehydes Tollens' aur (aliphatic hon to) Fehling's reagents ko reduce karte hain; ketones nahi karte. $C H_{3} C O$ – aur $C H_{3} C H (O H)$ – groups iodoform dete hain (oxidation).
α-Hydrogens acidic hote hain; dilute alkali ke saath yeh aldol reactions aur α,β-unsaturated products tak le jaate hain. Bina α-H wale aldehydes concentrated alkali ke saath Cannizzaro reaction dete hain (α-hydrogen reactions).
Carboxylic acids alcohols, aldehydes aur alkylbenzenes ko oxidise karke, nitriles, amides, acyl halides, anhydrides aur esters ko hydrolyse karke, aur RMgX + $C O_{2}$ se bante hain (Section 8.7).
Hydrogen-bonded dimers ki wajah se acids ke boiling points high hote hain; $C_{4}$ tak ke acids water mein mix ho jaate hain (Section 8.8).
Acids phenols se strong hain kyunki carboxylate ka charge do oxygens mein barabar baanta jaata hai; electron-withdrawing groups, unka paas hona aur sp² carbon acidity badhate hain (Section 8.9.1).
Acids se anhydrides, esters, acyl chlorides aur amides bante hain; yeh $L i A l H_{4}$ ya $B_{2} H_{6}$ se reduce hote hain, soda lime ke saath $C O_{2}$ khote hain, aur HVZ α-halogenation aur meta ring substitution dete hain (Section 8.9).

Flash cards · 15

Yaad rakhne wale named reactions

1 / 15

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 8.1	Practice 8.1 · Q1
NCERT Intext Question 8.2	Practice 8.2 · Q1
NCERT Intext Question 8.4	Practice 8.4–8.5 · Q1
NCERT Intext Question 8.5	Practice 8.4–8.5 · Q2
NCERT Intext Question 8.7	Practice 8.7 · Q1
NCERT Exercises 8.1	Exercises · Q1
NCERT Exercises 8.2	Exercises · Q2
NCERT Exercises 8.3	Exercises · Q3
NCERT Exercises 8.4	Exercises · Q4
NCERT Exercises 8.5	Exercises · Q5
NCERT Exercises 8.6	Exercises · Q6
NCERT Exercises 8.7	Exercises · Q7
NCERT Exercises 8.8	Exercises · Q8
NCERT Exercises 8.9	Exercises · Q9
NCERT Exercises 8.10	Exercises · Q10
NCERT Exercises 8.11	Exercises · Q11
NCERT Exercises 8.12	Exercises · Q12
NCERT Exercises 8.13	Exercises · Q13
NCERT Exercises 8.14	Exercises · Q14
NCERT Exercises 8.15	Exercises · Q15
NCERT Exercises 8.16	Exercises · Q16
NCERT Exercises 8.17	Exercises · Q17
NCERT Exercises 8.18	Exercises · Q18
NCERT Exercises 8.19	Exercises · Q19
NCERT Exercises 8.20	Exercises · Q20

Quick check: MCQs

8.1.2 Structure of the Carbonyl Group4 questions
8.2.3 Preparation of Ketones4 questions
8.3 Physical Properties4 questions
Kuch important addition reactions4 questions
Oxidation4 questions
Doosre reactions4 questions
8.6.2 Structure of Carboxyl Group4 questions
8.7 Methods of Preparation of Carboxylic Acids3 questions
8.8 Physical Properties2 questions
8.9.1 Reactions Involving Cleavage of O–H Bond5 questions
8.9.4 Substitution Reactions in the Hydrocarbon Part5 questions
8.10 Uses of Carboxylic Acids2 questions

Glossary · 14

Key terms (English + Hindi)

acetalऐसीटैलaiseetail: Ek carbon par do –OR groups wala compound, jo aldehyde aur do alcohol molecules se banta hai (ketone se bane to ketal).Chapter mein pehli baar yahan aaya →
aldehydeऐल्डिहाइडaildihaaid: Aisa carbonyl compound jiske carbonyl carbon par kam se kam ek hydrogen ho, RCHO.Chapter mein pehli baar yahan aaya →
aldolऐल्डोलaildol: β-hydroxy aldehyde ya ketone jo tab banta hai jab enolate C=O group par add hota hai.Chapter mein pehli baar yahan aaya →

Cannizzaro reactionकैनिज़ारो अभिक्रियाkainizaaro abhikriya: Concentrated alkali mein bina α-hydrogen wale aldehyde ka alcohol aur carboxylate mein disproportionation.Chapter mein pehli baar yahan aaya →
carbonyl groupकार्बोनिल समूहkaarbonil samooh: Oxygen atom se double bond se juda ek carbon atom, >C=O.Chapter mein pehli baar yahan aaya →
carboxylic acidकार्बोक्सिलिक अम्लkaarboksilik aml: Carboxyl group, –COOH, wala compound.Chapter mein pehli baar yahan aaya →
cyanohydrinसायनोहाइड्रिनsaayanohaaidrin: Ek hi carbon par –OH aur –CN wala compound, jo C=O par HCN add karke banta hai.Chapter mein pehli baar yahan aaya →

esterificationएस्टरीकरणestareekaran: Acid catalyst ki madad se carboxylic acid aur alcohol se ester aur water banna.Chapter mein pehli baar yahan aaya →

haloform reactionहैलोफॉर्म अभिक्रियाhailoform abhikriya: Hypohalite se methyl ketone ka $C H X_{3}$ aur ek carbon kam wale acid ke salt mein badalna.Chapter mein pehli baar yahan aaya →
hemiacetalहेमीऐसीटैलhemiaiseetail: Ek hi carbon par –OH aur –OR wala compound, jo aldehyde par ek alcohol molecule ke add hone se banta hai.Chapter mein pehli baar yahan aaya →

ketoneकीटोनkeeton: Aisa carbonyl compound jiske carbonyl carbon par do carbon groups hon, RCOR′.Chapter mein pehli baar yahan aaya →

nucleophilic additionनाभिकस्नेही योगज अभिक्रियाnaabhikasnehi yogaj abhikriya: C=O ke across addition jo δ+ carbon par nucleophile ke attack se shuru hota hai.Chapter mein pehli baar yahan aaya →

pKapKapee-ke-e: −log Ka; pKa jitna chhota, acid utna strong.Chapter mein pehli baar yahan aaya →

α-hydrogenα-हाइड्रोजनalpha-haaidrojan: C=O group ke bagal wale carbon par laga hydrogen; yeh acidic hai kyunki ise hatane se resonance-stabilised enolate milta hai.Chapter mein pehli baar yahan aaya →

8.1 Nomenclature and Structure of Carbonyl Group

8.1.1 Nomenclature

Common names

IUPAC names

8.1.2 Structure of the Carbonyl Group

8.2 Preparation of Aldehydes and Ketones

8.2.1 Preparation of Aldehydes and Ketones

8.2.2 Preparation of Aldehydes

8.2.3 Preparation of Ketones

8.3 Physical Properties

8.4 Chemical Reactions

Nucleophilic addition reactions

Mechanism

Reactivity

Kuch important addition reactions

Reduction

Oxidation

Reactions due to α-hydrogen

Aldol reaction

Cross aldol reaction

Doosre reactions

8.5 Uses of Aldehydes and Ketones

8.6 Nomenclature and Structure of Carboxyl Group

8.6.1 Nomenclature

8.6.2 Structure of Carboxyl Group

8.7 Methods of Preparation of Carboxylic Acids

8.8 Physical Properties

8.9 Chemical Reactions

8.9.1 Reactions Involving Cleavage of O–H Bond

8.9.2 Reactions Involving Cleavage of C–OH Bond

8.9.3 Reactions Involving –COOH Group

8.9.4 Substitution Reactions in the Hydrocarbon Part

8.10 Uses of Carboxylic Acids

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