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A mixture of primary, secondary, and tertiary amines can be separated using

1. Hinsberg's method
2. Hofmann's isocyanide test
3. Fractional distillation
4. NaNO2 and HCl

Correct answer: Hinsberg's method

Solution

Hinsberg's method uses benzenesulfonyl chloride (C6H5SO2Cl) in alkaline solution to distinguish and separate the three classes: primary amines form N-monosubstituted sulfonamides soluble in excess NaOH (acidic N-H); secondary amines form N,N-disubstituted sulfonamides insoluble in NaOH; tertiary amines do not react. This differential solubility allows complete separation.

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