Match List-I with List-II.
| List-I | List-II |
| (i) Ammonolysis | (a) Amine with a lesser number of carbon atoms |
| (ii) Gabriel phthalimide synthesis | (b) Test for primary amines |
| (iii) Hoffmann bromamide degradation | (c) Reaction of phthalimide with KOH and R–X |
| (iv) Carbylamine reaction | (d) Reaction of alkyl halides with NH3 |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (i)-(d), (ii)-(c), (iii)-(a), (iv)-(b)
Three of these reactions prepare amines: ammonolysis and Gabriel synthesis put an amino group in place of a halogen, and Hoffmann bromamide degradation turns an amide into an amine with one carbon less. The carbylamine reaction is a test that tells primary amines apart from secondary and tertiary ones.
(i) Ammonolysis — This matches (d) Reaction of alkyl halides with NH3. Ethanolic ammonia replaces the halogen by an amino group (sealed tube, 373 K). The amine formed can react further, so a mixture of amines results unless ammonia is in large excess.
\( \displaystyle \ce{R-X + NH3} \xrightarrow{373\,\mathrm{K}} \ce{R-NH2 + HX} \)
(ii) Gabriel phthalimide synthesis — This matches (c) Reaction of phthalimide with KOH and R–X. KOH forms potassium phthalimide, which is alkylated by R–X; alkaline hydrolysis then releases a pure primary amine.
\( \displaystyle \ce{C6H4(CO)2NH + KOH -> C6H4(CO)2N^-K^+ + H2O} \)
\( \displaystyle \ce{C6H4(CO)2N^-K^+ + R-X -> C6H4(CO)2N-R + KX} \)
\( \displaystyle \ce{C6H4(CO)2N-R + 2NaOH} \xrightarrow{\text{heat}} \ce{C6H4(COONa)2 + R-NH2} \)
(iii) Hoffmann bromamide degradation — This matches (a) Amine with a lesser number of carbon atoms. The carbonyl carbon of the amide leaves as carbonate, so the amine has one carbon fewer than the amide.
\( \displaystyle \ce{R-CONH2 + Br2 + 4NaOH -> R-NH2 + Na2CO3 + 2NaBr + 2H2O} \)
(iv) Carbylamine reaction — This matches (b) Test for primary amines. A primary amine heated with chloroform and ethanolic KOH gives a foul-smelling isocyanide; secondary and tertiary amines do not react.
\( \displaystyle \ce{R-NH2 + CHCl3 + 3KOH} \xrightarrow{\text{heat}} \ce{R-NC + 3KCl + 3H2O} \)
NCERT (2026-27 edition):
9.4 Preparation of Amines – “2. Ammonolysis of alkyl halides
… Hence, an alkyl or benzyl halide on reaction with an ethanolic solution of ammonia undergoes nucleophilic substitution reaction in which the halogen atom is replaced by an amino (–NH2) group. This process of cleavage of the C–X bond by ammonia molecule is known as ammonolysis.”
9.4 Preparation of Amines – “5. Gabriel phthalimide synthesis
… Phthalimide on treatment with ethanolic potassium hydroxide forms potassium salt of phthalimide which on heating with alkyl halide followed by alkaline hydrolysis produces the corresponding primary amine.”
9.4 Preparation of Amines – “6. Hoffmann bromamide degradation reaction
Hoffmann developed a method for preparation of primary amines by treating an amide with bromine in an aqueous or ethanolic solution of sodium hydroxide. … The amine so formed contains one carbon less than that present in the amide.”
9.6 Chemical Reactions – “4. Carbylamine reaction
Aliphatic and aromatic primary amines on heating with chloroform and ethanolic potassium hydroxide form isocyanides or carbylamines which are foul smelling substances. … This reaction is known as carbylamine reaction or isocyanide test and is used as a test for primary amines.”