chapter 13 Amines Class 12 Chemistry Textbook Solution

3. Answer the following

xi. Write reaction to convert ethylamine into methylamine.


i. Nucleophilic Substitution Reaction:

  • When an alkyl halide is heated with an alcoholic solution of excess ammonia, it undergoes a nucleophilic substitution reaction. In this reaction, the halogen atom in the alkyl halide is replaced by an amino group (-NH2), resulting in the formation of a primary amine.

ii. Ammonolysis and Alkylation:

  • This process of breaking the carbon-halogen (C-X) bond by ammonia is referred to as ammonolysis. It is also known as the alkylation of ammonia. This reaction is typically carried out in a sealed tube at a temperature of 373 K.

iii. Formation of Secondary and Tertiary Amines:

  • The primary amine obtained in the first step acts as a stronger nucleophile compared to ammonia. Consequently, it further reacts with alkyl halides to form secondary and tertiary amines, eventually leading to the formation of quaternary ammonium salts if ammonia (NH3) is not used in large excess.


\[\ce{\underset{\text{Alkyl halide}}{R – X} + \underset{\text{(excess)}}{NH3_{(alc.)}}->[\Delta] \underset{1^0}{R} – NH2 + HX}\]

iv. Reactivity Order:

  • The reactivity of alkyl halides with ammonia follows the order: R-I > R-Br > R-Cl. This order reflects the relative ease with which different alkyl halides undergo ammonolysis reactions.

These revised points maintain the original information while avoiding plagiarism.

13 Amines Class 12 Chemistry Textbook Solution page 297