COMEDK2022Chemistryp Block Elements (Group 15, 16, 17 & 18)
Which among the following will not liberate nitrogen on reaction with nitrous acid?
Options
- Adimethylamine
- B2-aminopropane
- Cethylamine
- Dmethylamine
Correct answer
A. dimethylamine
Step-by-step solution
Nitrous acid ( HNO₂ ) reacts with primary aliphatic amines ( R-NH₂ ) to form unstable diazonium salts, which decompose to evolve nitrogen gas ( N₂ ) and form alcohols. Ethylamine ( CH₃CH₂NH₂ ), methylamine ( CH₃NH₂ ), and 2-aminopropane ( (CH₃)₂CHNH₂ ) are all primary aliphatic amines and will liberate nitrogen gas. Dimethylamine ( (CH₃)₂NH ) is a secondary aliphatic amine. Secondary amines react with nitrous acid to form N-nitrosamines, which are yellow oily compounds. The reaction is: (CH₃)₂NH + HNO₂ (CH₃)₂N-N=O