JEE Main · 2025 · Shift-IeasyAMIN-014

Which of the following amine(s) show(s) positive carbylamines test? (A) Aniline (C6H5NH2) (B) (CH3)2NH (C) CH3NH2 (D)…

Amines · Class 12 · JEE Main Previous Year Question

Question

Which of the following amine(s) show(s) positive carbylamines test?

(A) Aniline (\ceC6H5NH2\ce{C6H5NH2})

(B) (\ceCH3)2\ceNH(\ce{CH3})_2\ce{NH}

(C) \ceCH3NH2\ce{CH3NH2}

(D) (\ceCH3)3\ceN(\ce{CH3})_3\ce{N}

(E) N-methylaniline (\ceC6H5NHCH3\ce{C6H5NHCH3})

Choose the correct answer from the options given below:

Options
  1. a

    A and E Only

  2. b

    C Only

  3. c

    A and C Only

  4. d

    B, C and D Only

Correct Answerc

A and C Only

Detailed Solution

Step 1: Recall the carbylamine (isocyanide) test

The carbylamine test is positive only for primary amines (1° amines — both aliphatic and aromatic).

Reaction: Primary amine + \ceCHCl3\ce{CHCl3} + alc. KOH → isocyanide (foul smell)

\ceRNH2+CHCl3+3KOH>RNC+3KCl+3H2O\ce{R-NH2 + CHCl3 + 3KOH -> R-NC + 3KCl + 3H2O}

Step 2: Classify each amine

| Amine | Type | Test | |---|---|---| | (A) Aniline \ceC6H5NH2\ce{C6H5NH2} | 1° aromatic | ✓ Positive | | (B) (\ceCH3)2\ceNH(\ce{CH3})_2\ce{NH} | 2° aliphatic | ✗ Negative | | (C) \ceCH3NH2\ce{CH3NH2} | 1° aliphatic | ✓ Positive | | (D) (\ceCH3)3\ceN(\ce{CH3})_3\ce{N} | 3° aliphatic | ✗ Negative | | (E) \ceC6H5NHCH3\ce{C6H5NHCH3} | 2° aromatic | ✗ Negative |

Step 3: Conclusion

Only (A) and (C) are primary amines → Answer: (c) A and C Only

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Which of the following amine(s) show(s) positive carbylamines test? (A) Aniline (C6H5NH2) (B)… (JEE Main 2025) | Canvas Classes