A hydrocarbon ‘P’ (C4H8) on reaction with HCl gives an optically active compound ‘Q’ (C4H9Cl) which on reaction with one mole of ammonia gives compound ‘R’ (C4H11N). ‘R’ on diazotization followed by hydrolysis gives ‘S’. Identify P, Q, R and S.

Since P (C4H8) reacts with HCl to give an optically active compound Q (C4H9Cl), P must be But-2-ene. Addition of HCl yields 2-chlorobutane, which possesses a chiral center. Compound Q reacts with NH3 to undergo nucleophilic substitution forming a primary amine R: Diazotization of primary aliphatic amines followed by hydrolysis yields an alcohol via a carbocation intermediate (S): An optically active alkyl halide formed from a C4H8 alkene with HX is a classic pointer to 2-halobutane originating from But-2-ene or But-1-ene. Diazotization of primary aliphatic amines (R-NH2) with NaNO2/HCl yields alcohols (R-OH) with possible rearrangements, though here a secondary carbocation is already stable. Class 12 Chemistry: Haloalkanes and Haloarenes Class 12 Chemistry: Amines

A hydrocarbon ‘P’ (C4H8) on reaction with HCl gives an optically active compound ‘Q’ (C4H9Cl) which on reaction with one mole of ammonia gives compound ‘R’ (C4H11N). ‘R’ on diazotization followed by h

Since P (C4H8) reacts with HCl to give an optically active compound Q (C4H9Cl), P must be But-2-ene. Addition of HCl yields 2-chlorobutane, which possesses a chiral center. Compound Q reacts with NH3 to undergo nucleophilic substitution forming a primary amine R: Diazotization of primary aliphatic amines followed by hydrolysis yields an alcohol via a carbocation intermediate (S): An optically active alkyl halide formed from a C4H8 alkene with HX is a classic pointer to 2-halobutane originating f

A hydrocarbon ‘P’ (C4H8) on reaction with HCl gives an optically active compound ‘Q’ (C4H9Cl) which on reaction with one mole of ammonia gives compound ‘R’ (C4H11N). ‘R’ on diazotization followed by hydrolysis gives ‘S’. Identify P, Q, R and S.

Since P (C4H8) reacts with HCl to give an optically active compound Q (C4H9Cl), P must be But-2-ene. Addition of HCl yields 2-chlorobutane, which possesses a chiral center. Compound Q reacts with NH3 to undergo nucleophilic substitution forming a primary amine R: Diazotization of primary aliphatic amines followed by hydrolysis yields an alcohol via a carbocation intermediate (S): An optically active alkyl halide formed from a C4H8 alkene with HX is a classic pointer to 2-halobutane originating from But-2-ene or But-1-ene. Diazotization of primary aliphatic amines (R-NH2) with NaNO2/HCl yields alcohols (R-OH) with possible rearrangements, though here a secondary carbocation is already stable. Class 12 Chemistry: Haloalkanes and Haloarenes Class 12 Chemistry: Amines

A hydrocarbon ‘P’ (C4H8) on reaction with HCl gives an optically active compound ‘Q’ (C4H9Cl) which on reaction with one mole of ammonia gives compound ‘R’ (C4H11N). ‘R’ on diazotization followed by h

Since P (C4H8) reacts with HCl to give an optically active compound Q (C4H9Cl), P must be But-2-ene. Addition of HCl yields 2-chlorobutane, which possesses a chiral center. Compound Q reacts with NH3 to undergo nucleophilic substitution forming a primary amine R: Diazotization of primary aliphatic amines followed by hydrolysis yields an alcohol via a carbocation intermediate (S): An optically active alkyl halide formed from a C4H8 alkene with HX is a classic pointer to 2-halobutane originating f

A hydrocarbon ‘P’ (C4H8) on reaction with HCl gives an optically active compound ‘Q’ (C4H9Cl) which on reaction with…

Year	2026	2025	2024	Total
Questions	11	16	13	40

Year

2026

2025

2024

Total

Questions

Solution & Explanation

Core Logic

Since P ( $C₄H₈$ $C_4H_8$) reacts with HCl to give an optically active compound Q ( $C₄H₉Cl$ $C_4H_9Cl$), P must be But-2-ene. Addition of HCl yields 2-chlorobutane, which possesses a chiral center.

CH₃-CH=CH-CH₃ HCl CH₃-CH₂-C^*H(Cl)-CH₃ (P is But-2-ene, Q is 2-chlorobutane)

Reactions of Haloalkanes diagram for Q54 - JEE Main 2026 Morning

Compound Q reacts with $NH₃$ $\mathrm{NH}_3$ to undergo nucleophilic substitution forming a primary amine R:

CH₃-CH₂-CH(Cl)-CH₃ NH₃ CH₃-CH₂-CH(NH₂)-CH₃ (R is Butan-2-amine)

Diazotization of primary aliphatic amines followed by hydrolysis yields an alcohol via a carbocation intermediate (S):

CH₃-CH₂-CH(NH₂)-CH₃ NaNO₂ / HCl / H₂O CH₃-CH₂-CH(OH)-CH₃ (S is Butan-2-ol)

Pattern Recognition

An optically active alkyl halide formed from a $C₄H₈$ $C_4H_8$ alkene with HX is a classic pointer to 2-halobutane originating from But-2-ene or But-1-ene. Diazotization of primary aliphatic amines ( $R-NH₂$ $R-NH_2$) with $NaNO₂/HCl$ $NaNO_2/HCl$ yields alcohols ( $R-OH$ $R-OH$) with possible rearrangements, though here a secondary carbocation is already stable.

Chapter Mix

Class 12 Chemistry: Haloalkanes and Haloarenes Class 12 Chemistry: Amines

More Haloalkanes and Haloarenes Previous-Year Questions — Page 8

Q74 jee_main_2024_30_jan_morning Classification

Given below are two statement one is labeled as Assertion (A) and the other is labeled as Reason (R). Assertion (A):

CH₂=CH-CH₂-Cl

is an example of allyl halide Reason (R): Allyl halides are the compounds in which the halogen atom is attached to

sp²

hybridised carbon atom. In the light of the two above statements, choose the most appropriate answer from the options given below:

A. $(A) is true but (R) is false$ $\text{(A) is true but (R) is false}$
B. $Both (A) and (R) are true but (R) is not the correct explanation of (A)$
C. $(A) is false but (R) is true$ $\text{(A) is false but (R) is true}$
D. $Both (A) and (R) are true and (R) is the correct explanation of (A)$