Consider the following sequence of reactions. Assuming that the reaction proceeds to completion, then 137 mg of 4-nitrotoluene will produce ___mg of B. (Given molar mass in g mol-1 H : 1, C : 12, N : 14, O : 16, Br : 80)

Follow the sequence of chemical transformations to determine the structure of product B, then apply stoichiometry based on moles of the starting material to find its final mass. Reaction 1: Reduction of 4-nitrotoluene using Sn, HCl / Delta followed by pH neutralization converts the -NO2 group to an -NH2 group, forming 4-methylaniline (p-toluidine). Reaction 2 (forming A): The aniline group is protected by reaction with acetic anhydride (CH3CO)2O, forming an acetanilide derivative (N-(4-methylphenyl)acetamide). Reaction 3 (forming B): Bromination using Br2 / AcOH. The -NHCOCH3 group is strongly activating and ortho-directing, while the -CH3 group is weakly activating and ortho-directing. The incoming -Br will substitute ortho to the -NHCOCH3 group due to dominant directing influence. Molar mass of 4-nitrotoluene (C7H7NO2) = 137 g/mol. Molar mass of product B (C9H10BrNO) = 228 g/mol. Moles of 4-nitrotoluene = 137 x 10-3 g137 g/mol = 0.001 mol. Since the stoichiometry is 1:1 and yields are 100%, moles of B = 0.001 mol. Mass of B = 0.001 mol x 228 g/mol = 0.228 g = 228 mg. When dealing with multi-step synthesis yield questions, immediately check the initial and final molar masses if the reaction achieves 100% completion. Often, 1 mole of reactant gives 1 mole of product. Class 12 Chemistry: Amines

Consider the following sequence of reactions. Assuming that the reaction proceeds to completion, then 137 mg of 4-nitrotoluene will produce ___mg of B. (Given molar mass in g mol-1 H : 1, C : 12, N :

Follow the sequence of chemical transformations to determine the structure of product B, then apply stoichiometry based on moles of the starting material to find its final mass. Reaction 1: Reduction of 4-nitrotoluene using Sn, HCl / Delta followed by pH neutralization converts the -NO2 group to an -NH2 group, forming 4-methylaniline (p-toluidine). Reaction 2 (forming A): The aniline group is protected by reaction with acetic anhydride (CH3CO)2O, forming an acetanilide derivative (N-(4-methylphe

Consider the following sequence of reactions. Assuming that the reaction proceeds to completion, then 137 mg of 4-nitrotoluene will produce ___mg of B. (Given molar mass in g mol-1 H : 1, C : 12, N : 14, O : 16, Br : 80)

Follow the sequence of chemical transformations to determine the structure of product B, then apply stoichiometry based on moles of the starting material to find its final mass. Reaction 1: Reduction of 4-nitrotoluene using Sn, HCl / Delta followed by pH neutralization converts the -NO2 group to an -NH2 group, forming 4-methylaniline (p-toluidine). Reaction 2 (forming A): The aniline group is protected by reaction with acetic anhydride (CH3CO)2O, forming an acetanilide derivative (N-(4-methylphenyl)acetamide). Reaction 3 (forming B): Bromination using Br2 / AcOH. The -NHCOCH3 group is strongly activating and ortho-directing, while the -CH3 group is weakly activating and ortho-directing. The incoming -Br will substitute ortho to the -NHCOCH3 group due to dominant directing influence. Molar mass of 4-nitrotoluene (C7H7NO2) = 137 g/mol. Molar mass of product B (C9H10BrNO) = 228 g/mol. Moles of 4-nitrotoluene = 137 x 10-3 g137 g/mol = 0.001 mol. Since the stoichiometry is 1:1 and yields are 100%, moles of B = 0.001 mol. Mass of B = 0.001 mol x 228 g/mol = 0.228 g = 228 mg. When dealing with multi-step synthesis yield questions, immediately check the initial and final molar masses if the reaction achieves 100% completion. Often, 1 mole of reactant gives 1 mole of product. Class 12 Chemistry: Amines

Consider the following sequence of reactions. Assuming that the reaction proceeds to completion, then 137 mg of 4-nitrotoluene will produce ___mg of B. (Given molar mass in g mol-1 H : 1, C : 12, N :

Follow the sequence of chemical transformations to determine the structure of product B, then apply stoichiometry based on moles of the starting material to find its final mass. Reaction 1: Reduction of 4-nitrotoluene using Sn, HCl / Delta followed by pH neutralization converts the -NO2 group to an -NH2 group, forming 4-methylaniline (p-toluidine). Reaction 2 (forming A): The aniline group is protected by reaction with acetic anhydride (CH3CO)2O, forming an acetanilide derivative (N-(4-methylphe

Consider the following sequence of reactions. Assuming that the reaction proceeds to completion, then 137 mg of…

Year	2026	2025	2024	Total
Questions	16	14	10	40

Q jee_main_2025_08_april_evening Functional Group Analysis and Identification

An organic compound 'A' undergoes the following sequence of transformations:

'A' [(ii) H₃O^+](i) NaOH 'B' [(ii) H₂SO₄, Δ](i) EtOH 'C'

* 'A' shows a positive Lassaigne's test for nitrogen and its molar mass is

121 g mol⁻¹

. * 'B' gives effervescence with aqueous

NaHCO₃

. * 'C' gives a characteristic fruity smell. Identify A, B, and C from the options below:

A.
B.
C.
D.

Solution

Core Logic

Let's perform a step-by-step diagnostic analysis:

Molar Mass & Nitrogen Test: Compound 'A' has a nitrogen atom and a molar mass of $121 g mol⁻¹$ $121 \text{ g mol}^{-1}$. Let's verify Benzamide ( $C₆H₅CONH₂$ $\text{C}_6\text{H}_5\text{CONH}_2$):

Mass = (7 \times 12) + (7 \times 1) + 14 + 16 = 84 + 7 + 14 + 16 = 121 g mol⁻¹

This matches perfectly.

Alkaline Hydrolysis: Hydrolysis of benzamide under basic conditions yields benzoic acid upon acidification:

C₆H₅CONH₂ [H₃O^+]NaOH C₆H₅COOH (Compound B) + NH₃

Benzoic acid reactively gives effervescence with $NaHCO₃$ $\text{NaHCO}_3$ due to the liberation of $CO₂$ $\text{CO}_2$ gas.

Esterification: Reaction of benzoic acid with ethanol in the presence of acid catalyst results in the creation of ethyl benzoate, an ester with a pleasant fruity smell:

C₆H₅COOH + EtOH H₂SO₄, Δ C₆H₅COOEt (Compound C) + H₂O

Esterification reaction mechanism diagram for Q28

Pattern Recognition

"Fruity smell" is an absolute indicator for an ester product. "Effervescence with $NaHCO₃$ $\text{NaHCO}_3$" dictates a carboxylic acid intermediate. Basic hydrolysis converting an organo-nitrogen compound into an acid points directly to an amide or a nitrile—molar mass calculation establishes benzamide over benzonitrile ( $M = 103$ $M = 103$).

Chapter Mix

Class 12 Chemistry: Amines Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids

Q41 jee_main_2025_29_jan_evening Diazotization and Coupling Reactions

Which one of the following reaction sequences will give an azo dye? (1) Nitrobenzene treated with (i)

Sn/HCl

, (ii)

NaNO₂/HCl

, (iii)

β

-naphthol,

NaOH

(2) Benzenesulfonic acid treated with (i)

SOCl₂

, (ii)

NH₃

, (iii) Benzyl chloride (3) Benzonitrile treated with (i)

70% H₂SO₄

, (ii)

PCl₅

, (iii) Aniline (4) Aniline treated with (i)

HCl/NaNO₂

, (ii) Toluene

A. Reaction sequence (1)
B. Reaction sequence (2)
C. Reaction sequence (3)
D. Reaction sequence (4)

Solution

Core Logic

Let's track sequence (1):

Nitrobenzene ( $Ph-NO₂$ $Ph-NO_2$) is reduced using $Sn/HCl$ $Sn/HCl$ to form Aniline ( $Ph-NH₂$ $Ph-NH_2$).
Aniline undergoing diazotization with $NaNO₂/HCl$ $NaNO_{2}/HCl$ at cold temperatures ( $0-5circC$ $0-5^{circ}C$) creates Benzene diazonium chloride ( $Ph-N₂⁺Cl⁻$ $Ph-N_{2}^{+}Cl^{-}$).
The diazonium salt undergoes a coupling reaction with $β$ $\beta$-naphthol in alkaline conditions ( $NaOH$ $NaOH$) to synthesize a highly vibrant red-orange azo dye.

Diazotization and Coupling Reactions diagram for Q41 - JEE Main 2025 Evening

Pattern Recognition

The standard sequence for azo dye preparation is: Aromatic Nitro $arrow$ $\rightarrow$ Primary Amine $arrow$ $\rightarrow$ Diazonium Salt $arrow$ $\rightarrow$ Phenol/Naphthol Coupling.

Chapter Mix

Class 12 Chemistry: Amines

Q49 jee_main_2025_28_jan_morning Yield and Stoichiometric Calculations

Consider the following sequence of reactions :

Reaction flow pathway for Q49 - JEE Main 2025 Morning — The flowchart tracks a chemical conversion starting from chlorobenzene down to final compound B.

11.25 mg of chlorobenzene will produce

x \times 10⁻¹

mg of product B. (Consider the reactions result in complete conversion.) [Given molar mass of C, H, O, N and Cl as 12, 1, 16, 14 and

35.5g mol⁻¹

respectively]

Numerical Answer. Answer: 93 to 93

Solution

Core Logic

The reaction sequence details the functional conversion of chlorobenzene down to product B (aniline, with a molar mass of $93 g mol⁻¹$ $93\,\mathrm{g\,mol}^{-1}$). Following stoichiometric preservation:

moles of chlorobenzene = moles of Aniline (B)

Molar mass of chlorobenzene ( $C₆H₅Cl$ $\mathrm{C}_6\mathrm{H}_5\mathrm{Cl}$) = $112.5 g mol⁻¹$ $112.5\,\mathrm{g\,mol}^{-1}$.

Molar stoichiometry relation graph for Q49 - JEE Main 2025 Morning — The flowchart tracks a chemical conversion starting from chlorobenzene down to final compound B.

moles = 11.25 \times 10⁻³ g112.5 g mol⁻¹ = 10⁻⁴ mol

Mass of product B produced:

Mass = 10⁻⁴ mol \times 93 g mol⁻¹ = 9.3 \times 10⁻³ g = 9.3 mg

Expressing in the specified format:

9.3 mg = 93 \times 10⁻¹ mg \Rightarrow x = 93

Pattern Recognition

Sees: Conversion sequence preserving a 1:1 mole ratio layout. Shortcut: Directly compute target weight via $WB = WA \cdot (MB)/(MA) = 11.25 \cdot (93)/(112.5) = 9.3$ .

Chapter Mix

Class 12 Chemistry: Amines

Q37 jee_main_2025_03_april_morning Diazonium Salts and Reactions

Identify [A], [B], and [C], respectively in the following reaction sequence:

Reaction scheme diagram for Q37 - JEE Main 2025 Morning — Reaction sequence starting from aniline reacting with NaNO2/HCl to give [A], which reacts with KI to give [B], and with 2Na/Dry ether to give [C].

A. Option (1)
B. Option (2)
C. Option (3)
D. Option (4)

Solution

Related Formula

Ar-NH₂ NaNO₂/HCl, 273-278K Ar-N₂^+Cl^- KI Ar-I

2 Ar-I 2Na, dry ether Ar-Ar (Fittig reaction)

Core Logic

Aniline with $NaNO₂/HCl$ $\mathrm{NaNO_2/HCl}$ at $273--278~K$ $273\text{--}278\mathrm{~K}$ undergoes diazotization to yield benzenediazonium chloride $[A] = C₆H₅N₂^+Cl^-$ .
Reaction of $[A]$ $[\mathrm{A}]$ with $KI$ $\mathrm{KI}$ replaces the diazonium group with iodine to form iodobenzene $[B] = C₆H₅I$ $[\mathrm{B}] = \mathrm{C_6H_5I}$.
Treating iodobenzene $[B]$ $[\mathrm{B}]$ with $2Na/dry ether$ $\mathrm{2Na/dry\ ether}$ yields biphenyl $[C] = C₆H₅-C₆H₅$ $[\mathrm{C}] = \mathrm{C_6H_5-C_6H_5}$ via the Fittig reaction.

Step 1: Option Matching

Option (3) correctly identifies $[A] = C₆H₅N₂^+Cl^-$ , $[B] = C₆H₅I$ $[\mathrm{B}] = \mathrm{C_6H_5I}$, and $[C] = Biphenyl$ $[\mathrm{C}] = \text{Biphenyl}$.

Pattern Recognition

Aniline $arrow$ $\rightarrow$ Diazotization $arrow$ $\rightarrow$ Iodination $arrow$ $\rightarrow$ Fittig coupling $arrow$ $\rightarrow$ Biphenyl.

Chapter Mix

Class 12 Chemistry: Amines

Q38 jee_main_2025_03_april_morning Reactions of Diazonium Salts

In the following reactions, which one is NOT correct?

A. Reaction (1)
B. Reaction (2)
C. Reaction (3)
D. Reaction (4)

Solution

Related Formula

Ar-N₂^+Cl^- + CH₃CH₂OH arrow Ar-H + N₂ + HCl + CH₃CHO

Core Logic

Reaction of benzenediazonium chloride with ethanol ( $EtOH$ $\mathrm{EtOH}$) is a reduction/deamination reaction that converts the diazonium salt to benzene, while ethanol gets oxidized to ethanal ( $CH₃CHO$ $\mathrm{CH_3CHO}$).

It does NOT yield phenetole (ethoxybenzene, $Ar-OEt$ $\mathrm{Ar-OEt}$). Therefore, Reaction (1) is incorrect.

Step 1: Verification of Other Reactions

Reaction with $H₃PO₂/H₂O$ $\mathrm{H_3PO_2/H_2O}$ gives benzene. (Correct)
Reaction with $KI$ $\mathrm{KI}$ gives iodobenzene. (Correct)
Reaction with $CuCN/KCN$ $\mathrm{CuCN/KCN}$ gives benzonitrile. (Correct)

Pattern Recognition

Diazonium salt + Ethanol $arrow$ $\rightarrow$ Benzene (reduction), NOT Ethoxybenzene.

Chapter Mix

Class 12 Chemistry: Amines

Solution & Explanation

Core Logic

Step 1: Reaction Sequence Analysis

Step 2: Acetylation

Step 3: Bromination

Step 4: Stoichiometric Calculation

Pattern Recognition

Chapter Mix

Reference Study Guides

More Amines Previous-Year Questions — Page 5

Solution

Core Logic

Pattern Recognition

Chapter Mix

Solution

Core Logic

Pattern Recognition

Chapter Mix

Solution

Core Logic

Pattern Recognition

Chapter Mix

Solution

Related Formula

Core Logic

Step 1: Option Matching

Pattern Recognition

Chapter Mix

Solution

Related Formula

Core Logic

Step 1: Verification of Other Reactions

Pattern Recognition

Chapter Mix

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