The correct formula of Hinsberg's reagent is :
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Secondary amines produce sulphonamides that do not dissolve in base.
Tertiary amines do not react with the reagent at all.
- \( \text{C}_6\text{H}_5\text{COCl} \)
- \( \text{C}_6\text{H}_5\text{SO}_2\text{Cl} \)
- \( \text{C}_6\text{H}_5\text{CONHCH}_3 \)
- \( \text{C}_6\text{H}_5\text{CH}_2\text{NH}_2 \)
The Correct Option is B
Solution and Explanation
• Hinsberg's reagent is the common name for Benzene Sulphonyl Chloride.
• It is used as a chemical test to classify amines into primary, secondary, or tertiary.
• The reagent reacts with the amine to form a sulphonamide derivative.
Step 1: Structural identification
Benzene sulphonyl chloride consists of a benzene ring \( (\text{C}_6\text{H}_5) \).
Attached to this ring is a sulphonyl group \( (-\text{SO}_2-) \).
The sulphonyl group is further bonded to a chlorine atom \( (-\text{Cl}) \).
Combining these parts gives the molecular formula: \( \text{C}_6\text{H}_5\text{SO}_2\text{Cl} \).
Step 2: Differentiating from other options
Option (A) is Benzoyl Chloride \( (\text{C}_6\text{H}_5\text{COCl}) \).
Option (C) is N-Methylbenzamide \( (\text{C}_6\text{H}_5\text{CONHCH}_3) \).
Option (D) is Benzylamine \( (\text{C}_6\text{H}_5\text{CH}_2\text{NH}_2) \).
Step 3: Application in the Hinsberg test
When a primary amine reacts with \( \text{C}_6\text{H}_5\text{SO}_2\text{Cl} \), it forms a sulphonamide with an acidic hydrogen.
This product is soluble in alkali \( (\text{NaOH}) \).
\[ \text{C}_6\text{H}_5\text{SO}_2\text{Cl} + \text{R-NH}_2 \rightarrow \text{C}_6\text{H}_5\text{SO}_2\text{NHR} \]
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(iv) (CH3 )3CNH2 (v) C6H5NHCH3 (vi) (CH3CH2 )2NCH3 (vii) m–BrC6H4NH2
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Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines.
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Arrange the following:
(i) In decreasing order of the pKb values: C2H5NH2 , C6H5NHCH3 , (C2H5 )2NH and C6H5NH2
(ii) In increasing order of basic strength: C6H5NH2 , C6H5N(CH3 )2 , (C2H5 )2NH and CH3NH2
(iii) In increasing order of basic strength: (a) Aniline, p-nitroaniline and p-toluidine Exercises Rationalised 2023-24 279 Amines (b) C6H5NH2 , C6H5NHCH3 , C6H5CH2NH2 .
(iv) In decreasing order of basic strength in gas phase: C2H5NH2 , (C2H5 )2NH, (C2H5 )3N and NH3
(v) In increasing order of boiling point: C2H5OH, (CH3 )2NH, C2H5NH2
(vi) In increasing order of solubility in water: C6H5NH2 , (C2H5 )2NH, C2H5NH2 .
How will you convert:
(i) Ethanoic acid into methanamine
(ii) Hexanenitrile into 1-aminopentane
(iii) Methanol to ethanoic acid
(iv) Ethanamine into methanamine
(v) Ethanoic acid into propanoic acid
(vi) Methanamine into ethanamine
(vii) Nitromethane into dimethylamine
(viii) Propanoic acid into ethanoic acid?
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