Match List - I with List - II. List - I (Reactions) List - II (Reagents) (A) CH3(CH2)5-CO-OC2H5 arrow CH3(CH2)5CHO (I) CH3MgBr, H2O (B) C6H5COC6H5 arrow C6H5CH2C6H5 (II) Zn(Hg) and conc. HCl (C) C6H5CHO arrow C6H5CH(OH)CH3 (III) NaBH4, H^+ (D) CH3COCH2COOC2H5 arrow CH3CH(OH)CH2COOC2H5 (IV) DIBAL-H, H2O Choose the correct answer from options given below:

### Core Logic Let's analyze the transformation happening in each reaction: (A) CH3(CH2)5COOC2H5 arrow CH3(CH2)5CHO An ester is reduced to an aldehyde. This is a selective reduction achieved using DIBAL-H (Diisobutylaluminium hydride) followed by hydrolysis. Thus, (A) arrow (IV). (B) C6H5COC6H5 arrow C6H5CH2C6H5 A ketone (carbonyl group >C=O) is fully reduced to an alkane (>CH2) methylene group. This is the Clemmensen reduction, which uses Zinc amalgam and concentrated HCl. Thus, (B) arrow (II). (C) C6H5CHO arrow C6H5CH(OH)CH3 Benzaldehyde (aldehyde) is converted into a secondary alcohol with an extra methyl group. This is a nucleophilic addition of a Grignard reagent (CH3MgBr) followed by hydrolysis. Thus, (C) arrow (I). (D) CH3COCH2COOC2H5 arrow CH3CH(OH)CH2COOC2H5 A ketone group is reduced to a secondary alcohol while the ester group remains intact. NaBH4 is a mild reducing agent that reduces aldehydes and ketones but generally does not touch esters. Thus, (D) arrow (III). ### Pattern Recognition Ester arrow Aldehyde = DIBAL-H Ketone arrow Alkane = Clemmensen (Zn(Hg)/HCl) or Wolff-Kishner Carbonyl arrow Alcohol with carbon chain extension = Grignard Reagent Ketone arrow Alcohol (leaving ester intact) = NaBH4 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Match List - I with List - II. List - I (Reactions) List - II (Reagents) (A) CH3(CH2)5-CO-OC2H5 arrow CH3(CH2)5CHO (I) CH3MgBr, H2O (B) C6H5COC6H5 arrow C6H5CH2C6H5 (II) Zn(Hg) and conc. HCl (C) C6H5C

### Core Logic Let's analyze the transformation happening in each reaction: (A) CH3(CH2)5COOC2H5 arrow CH3(CH2)5CHO An ester is reduced to an aldehyde. This is a selective reduction achieved using DIBAL-H (Diisobutylaluminium hydride) followed by hydrolysis. Thus, (A) arrow (IV). (B) C6H5COC6H5 arrow C6H5CH2C6H5 A ketone (carbonyl group >C=O) is fully reduced to an alkane (>CH2) methylene group. This is the Clemmensen reduction, which uses Zinc amalgam and concentrated HCl. Thus, (B) arrow (II).

Match List - I with List - II. List - I (Reactions) List - II (Reagents) (A) CH3(CH2)5-CO-OC2H5 arrow CH3(CH2)5CHO (I) CH3MgBr, H2O (B) C6H5COC6H5 arrow C6H5CH2C6H5 (II) Zn(Hg) and conc. HCl (C) C6H5CHO arrow C6H5CH(OH)CH3 (III) NaBH4, H^+ (D) CH3COCH2COOC2H5 arrow CH3CH(OH)CH2COOC2H5 (IV) DIBAL-H, H2O Choose the correct answer from options given below:

### Core Logic Let's analyze the transformation happening in each reaction: (A) CH3(CH2)5COOC2H5 arrow CH3(CH2)5CHO An ester is reduced to an aldehyde. This is a selective reduction achieved using DIBAL-H (Diisobutylaluminium hydride) followed by hydrolysis. Thus, (A) arrow (IV). (B) C6H5COC6H5 arrow C6H5CH2C6H5 A ketone (carbonyl group >C=O) is fully reduced to an alkane (>CH2) methylene group. This is the Clemmensen reduction, which uses Zinc amalgam and concentrated HCl. Thus, (B) arrow (II). (C) C6H5CHO arrow C6H5CH(OH)CH3 Benzaldehyde (aldehyde) is converted into a secondary alcohol with an extra methyl group. This is a nucleophilic addition of a Grignard reagent (CH3MgBr) followed by hydrolysis. Thus, (C) arrow (I). (D) CH3COCH2COOC2H5 arrow CH3CH(OH)CH2COOC2H5 A ketone group is reduced to a secondary alcohol while the ester group remains intact. NaBH4 is a mild reducing agent that reduces aldehydes and ketones but generally does not touch esters. Thus, (D) arrow (III). ### Pattern Recognition Ester arrow Aldehyde = DIBAL-H Ketone arrow Alkane = Clemmensen (Zn(Hg)/HCl) or Wolff-Kishner Carbonyl arrow Alcohol with carbon chain extension = Grignard Reagent Ketone arrow Alcohol (leaving ester intact) = NaBH4 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Match List - I with List - II. List - I (Reactions) List - II (Reagents) (A) CH3(CH2)5-CO-OC2H5 arrow CH3(CH2)5CHO (I) CH3MgBr, H2O (B) C6H5COC6H5 arrow C6H5CH2C6H5 (II) Zn(Hg) and conc. HCl (C) C6H5C

### Core Logic Let's analyze the transformation happening in each reaction: (A) CH3(CH2)5COOC2H5 arrow CH3(CH2)5CHO An ester is reduced to an aldehyde. This is a selective reduction achieved using DIBAL-H (Diisobutylaluminium hydride) followed by hydrolysis. Thus, (A) arrow (IV). (B) C6H5COC6H5 arrow C6H5CH2C6H5 A ketone (carbonyl group >C=O) is fully reduced to an alkane (>CH2) methylene group. This is the Clemmensen reduction, which uses Zinc amalgam and concentrated HCl. Thus, (B) arrow (II).

Match List - I with List - II. List - I (Reactions) List - II (Reagents) (A) CH3(CH2)5-CO-OC2H5 arrow CH3(CH2)5CHO (I)…

Year	2026	2025	2024	Total
Questions	14	21	11	46

List - I (Reactions)	List - II (Reagents)
(A) $CH₃(CH₂)₅-CO-OC₂H₅ arrow CH₃(CH₂)₅CHO$	(I) $CH₃MgBr, H₂O$ $CH_3MgBr, H_2O$
(B) $C₆H₅COC₆H₅ arrow C₆H₅CH₂C₆H₅$	(II) $Zn(Hg)$ $Zn(Hg)$ and conc. $HCl$ $HCl$
(C) $C₆H₅CHO arrow C₆H₅CH(OH)CH₃$	(III) $NaBH₄, H^+$ $NaBH_4, H^+$
(D) $CH₃COCH₂COOC₂H₅ arrow CH₃CH(OH)CH₂COOC₂H₅$	(IV) DIBAL-H, $H₂O$ $H_2O$

Q45 jee_main_2025_24_jan_morning Chemical Reactions of Ketones

The product (A) formed in the following reaction sequence is :

C H _ 3 - C \equiv C H [ (i i) H _ 2 / N i ](i) H g ^ 2 +, H _ 2 S O _ 4 (A)

A. $CH₃-C(NH₂)(CH₃)-CH₂-OH$
B. $CH₃-C(OH)(CH₃)-CH₂-NH₂$
C. $CH₃-CH₂-CH(OH)-CH₂-OH$
D. $CH₃-CH(OH)-CH(CH₃)-NH₂$

Solution

Core Logic

Breaking down the multi-step reaction path sequence:

Hydration of propyne using Kucherov's trigger condition ( $Hg²⁺, H₂SO₄$ $Hg^{2+}, H_2SO_4$) adds water across the triple bond via Markovnikov's rule. The intermediate enol undergoes tautomerization to yield acetone ( $CH₃-CO-CH₃$ $CH_3-CO-CH_3$).
Reacting acetone with $HCN$ $HCN$ drives nucleophilic addition at the carbonyl carbon, forming a cyanohydrin intermediate: $CH₃-C(OH)(CH₃)-CN$ $CH_3-C(OH)(CH_3)-CN$.
Introducing a reducing agent ( $H₂/Ni$ $H_2/Ni$) selectively converts the nitrile group ( $-CN$ $-CN$) into a primary amine side chain ( $-CH₂-NH₂$ $-CH_2-NH_2$).

The final synthesized structure is: $CH₃-C(OH)(CH₃)-CH₂-NH₂$ .

Chemical Reactions of Ketones step sequence product chart for Q45

Pattern Recognition

Alkyne hydration produces a ketone carbonyl system. Cyanohydrin synthesis introduces a carbon coordinate, which subsequently reduces to a primary aliphatic amine functional group.

Chapter Mix

Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Q48 jee_main_2025_24_jan_morning Reactions of Carboxylic Acids

Xg of benzoic acid on reaction with aq.

NaHCO₃

release

CO₂

that occupied 11.2 L volume at STP. X is ______ g.

Numerical Answer. Answer: 61 to 61

Solution

Related Formula

Moles of gas at STP = V in Liters22.4 L/mol

Core Logic

The balanced acid-base reaction equation is:

C₆H₅COOH + NaHCO₃ arrow C₆H₅COO⁻Na⁺ + H₂O + CO₂

This stoichiometry shows a $1:1$ $1:1$ molar ratio between benzoic acid and the released carbon dioxide gas.

Calculate the total moles of evolved $CO₂$ $CO_2$ gas at standard conditions:

moles of CO₂ = 11.2 L22.4 L mol⁻¹ = 0.5 moles

Thus, the reaction consumed exactly $0.5 moles$ $0.5\text{ moles}$ of benzoic acid ( $C₆H₅COOH$ $C_6H_5COOH$, molecular weight = $122 g/mol$ $122\text{ g/mol}$):

mass consumed (X) = 0.5 \times 122 = 61 grams

Pattern Recognition

Carboxylic acids react with sodium bicarbonate in a straightforward $1:1$ $1:1$ molar ratio, releasing exactly 1 mole of carbon dioxide gas per mole of acid group.

Chapter Mix

Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Q37 jee_main_2025_28_jan_evening Oxidation of Alkylbenzenes

The total number of compounds from below when treated with hot

KMnO₄

giving benzoic acid is:

Alkylbenzene structures for Q37 - JEE Main 2025 — The image lists seven distinct aromatic side-chain hydrocarbon structures to assess for side-chain oxidation.

A. 3
B. 4
C. 6
D. 5

Solution

Related Formula

Side-chain oxidation criteria:

Ar-CH(R)₂ hot KMnO₄ Ar-COOH

Requires the presence of at least one benzylic hydrogen atom on the aromatic side chain structure.

Core Logic

Alkyl side chains on a benzene ring are oxidized entirely down to a carboxylic acid group (benzoic acid) by strong oxidizing agents like hot alkaline $KMnO₄$ $KMnO_4$, provided the benzylic carbon contains at least one hydrogen atom.

Evaluating the structures from the diagram:

Toluene (contains $3$ $3$ benzylic H) $arrow$ $\rightarrow$ Yields benzoic acid
Ethylbenzene (contains $2$ $2$ benzylic H) $arrow$ $\rightarrow$ Yields benzoic acid
Isopropylbenzene / Cumene (contains $1$ $1$ benzylic H) $arrow$ $\rightarrow$ Yields benzoic acid
tert-Butylbenzene (contains $0$ $0$ benzylic H) $arrow$ $\rightarrow$ Resists oxidation
Isobutylbenzene (contains $2$ $2$ benzylic H) $arrow$ $\rightarrow$ Yields benzoic acid
2-Phenylpropan-2-ol (contains $0$ $0$ benzylic H, tertiary alcohol center) $arrow$ $\rightarrow$ Resists oxidation
n-Propylbenzene (contains $2$ $2$ benzylic H) $arrow$ $\rightarrow$ Yields benzoic acid
The last biphenyl derivative undergoes complex disruption or ring cleavages and does not cleanly yield simple benzoic acid under standard monocyclic oxidation definitions.

Step 1: Counting Valid Targets

The compounds that undergo oxidation to form benzoic acid are toluene, ethylbenzene, isopropylbenzene, isobutylbenzene, and n-propylbenzene.

Total count = 5 compounds.

Structural evaluation summary for side-chain oxidation targets — The image lists seven distinct aromatic side-chain hydrocarbon structures to assess for side-chain oxidation.

Pattern Recognition

Look immediately at the benzylic carbon (the carbon bonded directly to the ring). If it is a quaternary center (like in tert-butylbenzene) or lacks a hydrogen atom entirely, mark it as unreactive to hot $KMnO₄$ $KMnO_4$ side-chain oxidation.

Chapter Mix

Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Q jee_main_2025_29_jan_morning Clemmensen Reduction

The product (P) formed in the following reaction is:

Clemmensen Reduction diagram for Q41 - JEE Main 2025 Morning — The structural flowchart indicates a multi-functional molecule treated with Zn-Hg/HCl.

A.
B.
C.
D.

Solution

Related Formula

R-CO-R' [HCl]Zn-Hg R-CH₂-R'

Core Logic

The provided reaction relies on classic Clemmensen Reduction reagent configurations ( $Zn-Hg / HCl$ $\mathrm{Zn-Hg} / \mathrm{HCl}$). This reagent explicitly selective targets ketone/aldehyde carbonyl centers ( $>C=O$ $>\mathrm{C}=\mathrm{O}$) and converts them cleanly into methylene units ( $-CH₂-$ $-\mathrm{CH}_2-$). Any free aliphatic alcohol functionalities ( $-OH$ $-\mathrm{OH}$) located on the ring are preserved under these reductive conditions. Thus, the ketone group on the ring is cleanly converted to $-CH₂-$ $-\mathrm{CH}_2-$, yielding option (3):

Clemmensen Reduction solution diagram for Q41 - JEE Main 2025 Morning — The structural flowchart indicates a multi-functional molecule treated with Zn-Hg/HCl.

Pattern Recognition

Clemmensen routes deoxygenate carbonyl clusters selectively without compromising adjacent standalone cyclic alcohol structural components.

Chapter Mix

Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Q jee_main_2025_29_jan_morning Chemical Reactions of Carbonyl Compounds

Based on the reaction sequence:

Organic synthesis reaction sequence diagram for Q50 - JEE Main 2025 Morning — A structural flow charts the transformation of a cyclic dialcohol into final product S.

0.1 mole of compound 'S' will weigh ________ g. (Given molar mass in

g mol⁻¹

C:12, H:1, O:16)

Numerical Answer. Answer: 13 to 13

Solution

Related Formula

Mass = Moles \cdot Molar Mass

Core Logic

Let us trace the reaction scheme row-by-row:

Organic synthesis intermediate layout mapping — A structural flow charts the transformation of a cyclic dialcohol into final product S.

Reactant: 2-(hydroxymethyl)cyclopentan-1-ol.
Step 1: Excess $CrO₃$ $\mathrm{CrO}_3$ (Jones oxidation) oxidizes the secondary alcohol to a ketone and the primary alcohol to a carboxylic acid $arrow$ $\rightarrow$ Product P.
Step 2: Reaction with 1 mole of glycol protects the ketone selectively as a cyclic ketal $arrow$ $\rightarrow$ Product Q.
Step 3: Treatment with $CH₃MgI$ $\mathrm{CH}_3\mathrm{MgI}$ targets the free carboxylic acid (or ester equivalent) to form a methyl ketone after workup $arrow$ $\rightarrow$ Product R.
Step 4: $NaBH₄$ $\mathrm{NaBH}_4$ reduces the methyl ketone to a secondary alcohol, and acid workup deprotects the ketal back to the original ketone $arrow$ $\rightarrow$ Compound S.

Chemical structural formula of S: 2-(1-hydroxyethyl)cyclopentan-1-one ( $C₇H₁₂O₂$ ).

Molar mass of S ( $C₇H₁₂O₂$ ):

M = (7 \cdot 12) + (12 \cdot 1) + (2 \cdot 16) = 84 + 12 + 32 = 130 ~g/mol

Mass of 0.1 mole = 0.1 \cdot 130 = 13 ~g

Pattern Recognition

Ketal groups serve as stable protective masks that shield ketones, allowing selective organometallic reactions to take place elsewhere on the molecule.

Chapter Mix

Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Solution & Explanation

Core Logic

Pattern Recognition

Chapter Mix

More Aldehydes, Ketones and Carboxylic Acids Previous-Year Questions — Page 7

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Core Logic

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Solution

Related Formula

Core Logic

Pattern Recognition

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Solution

Related Formula

Core Logic

Step 1: Counting Valid Targets

Pattern Recognition

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Solution

Related Formula

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Pattern Recognition

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Related Formula

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