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JEE · NEET Previous Year Question

Total number of alkali insoluble solid sulphonamides obtained by reaction of given amines with Hinsberg's reagent is .
Aniline, N-Methylaniline, Methanamine, N, N-Dimethylmethanamine, N-Methyl methanamine, Phenylmethanamine, N-propylaniline, N-phenylaniline, N, N-Dimethylaniline, Allyl amine, Isopropyl amine

Topic: JEE PYQ

Answer: C. Full step-by-step solution below.

  1. A2
  2. B5
  3. C4
  4. D8

Correct answer: C

Solution

(c) Hinsberg's reagent (benzenesulfonyl chloride) classifies amines by their reaction products:
Primary amines form alkali-soluble sulfonamides (soluble in NaOH ).
Secondary amines ( ) form alkali-insoluble sulfonamides (precipitate in NaOH ).
Tertiary amines do not react.
Analyzing the given amines:
Aniline (primary), Methanamine (primary), Phenylmethanamine (primary), Allyl amine (primary), Isopropyl amine (primary) → alkali-soluble.
-Dimethylmethanamine (tertiary), -Dimethylaniline (tertiary) → no reaction.
N-Methylaniline (secondary), N-Methyl methanamine (secondary), N-Propylaniline (secondary), N-Phenylaniline (secondary) → alkali-insoluble.
Total alkali-insoluble sulfonamides: 4.

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