NEET · Chemistry —

Amines appeared 3 times across 1 year — 6.7% of Chemistry. This question is from Aliphatic Amines Synthesis.

Year 2024 Total
Questions 3 3
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The major product Z formed in the following sequence of reactions is C₂H₆ [UV light]Cl₂ X(monochlorinated Product) NH₃ Y [(ii)H₂O](i)NaNO₂ Z

Solution & Explanation

Core Logic

Step 1: Free radical chlorination of Ethane:

C₂H₆ + Cl₂ UV C₂H₅Cl (X)

Step 2: Nucleophilic substitution (Ammonolysis):

C₂H₅Cl NH₃ C₂H₅NH₂ (Y)

Step 3: Diazotization and Hydration of aliphatic primary amine:

C₂H₅NH₂ NaNO₂ / HCl [C₂H₅N₂^+ Cl^-] H₂O C₂H₅OH + N₂ + HCl (Z)
Step 1: Final Conclusion

Solution for Q47 - Amines Reaction Scheme
Solution for Q47 - Amines Reaction Scheme
The final major product Z is Ethanol (C₂H₅OH).

Pattern Recognition

Aliphatic primary amines react with nitrous acid (NaNO₂ + HCl) to form unstable diazonium salts, which immediately decompose in water to yield the corresponding alcohol and release nitrogen gas.

Chapter Mix

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

Reference Study Guides

Amines

More Amines Previous-Year Questions

Q61 neet_2026_03_may_morning Preparation of Amines
Select the reagents that reduce nitriles to primary amines. A. (i) LiAlH₄ ; (ii) H₂O B. Sn + HCl C. H₂/Ni D. Na(Hg)/C₂H₅OH E. Br₂/aq. NaOH Choose the correct answer from the options given below.
  • A. A, B and C only
  • B. A, C and D only
  • C. A, D and E only
  • D. B, D and E only

Solution

Core Logic

Reduction of Nitriles (R-CN) to Primary Amines (R-CH₂-NH₂) can be achieved using strong reducing agents or catalytic hydrogenation:

  • R-CN Na(Hg) / C₂H₅OH R-CH₂-NH₂ (Mendius Reduction - Reagent D is correct)
  • R-CN [(ii)H₂O](i)LiAlH₄ R-CH₂-NH₂ (Strong Hydride Reduction - Reagent A is correct)
  • R-CN H₂ / Ni R-CH₂-NH₂ (Catalytic Hydrogenation - Reagent C is correct)

    • Incorrect Reagents:

  • R-CN Sn + HCl R-CHO (Stephen reaction reduces nitriles to aldehydes, not amines - Reagent B is incorrect).
  • Br₂/aq. NaOH is used for Hoffmann bromamide degradation of amides, not nitriles (Reagent E is incorrect).
Step 1: Final Conclusion

Reagents A, C, and D are correct for reducing nitriles to primary amines.

Pattern Recognition

Nitriles require full reduction (addition of 4 Hydrogens) to become primary amines. Mild reducing agents like Sn/HCl (Stephen's reduction) stop at the imine stage, hydrolyzing to an aldehyde.

Chapter Mix

Class 12 Chemistry: Amines

Q89 neet_2026_03_may_morning Reactions of Amines
The following two reactions give the same foul smelling product Z. C₂H₅CI X Z C₂H₅CONH₂ Br₂, NaOH Y [Δ]CHCl₃ / ethanolic KOH Z X and Z, respectively, are :
  • A. X = AgCN ; Z = C₂H₅CN
  • B. X = KCN ; Z = C₂H₅CN
  • C. X = KCN ; Z = C₂H₅NC
  • D. X = AgCN ; Z = C₂H₅NC

Solution

Core Logic

Step 1: Analyze the second reaction sequence (bottom).

  • C₂H₅CONH₂ Br₂, NaOH Y: This is Hoffmann bromamide degradation. The amide loses its carbonyl group to form a primary amine: C₂H₅NH₂ (Y).
  • C₂H₅NH₂ CHCl₃ / KOH, Δ Z: This is the Carbylamine reaction (isocyanide test). Primary amines react to form highly offensive, foul-smelling isocyanides. Thus, Z is Ethyl isocyanide (C₂H₅NC).

    • Step 2: Analyze the first reaction (top).

  • C₂H₅Cl X C₂H₅NC (Z).
  • To convert an alkyl chloride directly into an isocyanide, we use Silver Cyanide (AgCN) because it is predominantly covalent, ensuring bonding through the Nitrogen atom rather than the Carbon atom (which happens with ionic KCN).
Step 1: Final Conclusion

Therefore, Reagent X is AgCN and product Z is C₂H₅NC.

Pattern Recognition

AgCN yields isocyanides (R-NC). KCN yields cyanides/nitriles (R-CN). "Foul smelling" is the universal keyword for Carbylamine test (isocyanides).

Chapter Mix

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

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)