KCET2009ChemistryAmines
Arrange the following in the increasing order of their basic strengths CH ₃ NH ₂, ( CH ₃ )₂ NH , ( CH ₃ )₃ ~N , NH ₃
Options
- ANH ₃ < ( CH ₃ )₃ ~N < ( CH ₃ )₂ NH < CH ₃ NH ₂
- BNH ₃ < ( CH ₃ )₃ ~N < CH ₃ NH ₂ < ( CH ₃ )₂ NH
- C( CH ₃ )₃ ~N < NH ₃ < CH ₃ NH ₂ < ( CH ₃ )₂ NH
- DCH ₃ NH ₂ < ( CH ₃ )₂ NH < ( CH ₃ )₃ ~N < NH ₃
Correct answer
B. NH ₃ < ( CH ₃ )₃ ~N < CH ₃ NH ₂ < ( CH ₃ )₂ NH
Step-by-step solution
Aliphatic amines are more basic than NH ₃ due to +I effect of alkyl groups. In aqueous medium tertiary amine is less basic than secondary amine because the cation formed by protonation of tertiary amine is less solvated as compared to the cation formed by protonation of secondary amine. Hence, the increasing order of their basic strength is as: NH ₃ < ( CH ₃ )₃ ~N < CH ₃ NH ₂ < ( CH ₃ )₂ NH