Answers: Amines Worksheet

 

Answers: Amines Worksheet

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Section A: Objective Questions

1. IUPAC Name: N-Methylmethanamine

2. Tertiary amines do not react with Hinsberg’s reagent because they do not have a replaceable hydrogen atom on the nitrogen.

3. Isomerism:
   (a) Functional isomerism
   (b) Position isomerism

4. Order of Basicity:
   ${\text{C}}_6{\text{H}}_5{\text{NH}}_2<{\text{CH}}_3{\text{NH}}_2<({\text{CH}}_3{)}_2\text{NH}$

5. Structure of N-ethylethanamine:
   ${\text{CH}}_3{\text{CH}}_2{\text{NHCH}}_2{\text{CH}}_3$

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Section B: Short Answer Questions

6. Conversions:
   (a) Nitrobenzene to Aniline:
   

   (b) Aniline to p-Bromoaniline:
   
   

   

6. Reaction of Ethylamine with Benzoyl Chloride (Hinsberg Test):

   • Ethylamine reacts with benzoyl chloride to form N-ethylbenzamide.
   • Mechanism: The lone pair of electrons on the nitrogen of ethylamine attacks the carbonyl carbon of benzoyl chloride, displacing the chlorine atom.

7. Aniline is less basic than methylamine because:

   • The lone pair of electrons on nitrogen in aniline is delocalized into the benzene ring, reducing its availability for protonation.

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Section C: Long Answer Questions

9. Hoffmann Bromamide Reaction:
   $\text{RCONH}_2 + \text{Br}_2 + 4\text{NaOH} \rightarrow \text{RNH}_2 + \text{Na}_2\text{CO}_3 + 2\text{NaBr} + 2\text{H}_2\text{O}$

   • Importance: Used to prepare primary amines from amides, with the loss of one carbon atom from the chain.

(a) Distinguish:

• Aniline vs. N-Methylaniline:
  Add bromine water: Aniline gives a white precipitate (2,4,6-tribromoaniline), while N-methylaniline does not.

• Primary amine vs. Tertiary amine:
  Hinsberg Test: Primary amines react to form soluble sulfonamide, while tertiary amines do not react.

(b) Coupling Reaction with Diazonium Salts:

• Reaction: $\text{C}_6\text{H}_5\text{N}_2^+ + \text{C}_6\text{H}_5\text{OH} \xrightarrow{\text{OH}^-} \text{C}_6\text{H}_5\text{-N=N-}\text{C}_6\text{H}_4\text{OH}$
• Diazonium salts react with phenols or aromatic amines to form azo compounds, used in dye synthesis.