MHT CET202526 Apr 2025Morning ShiftChemistryAminesActual
What is the expected order of basic strength of different compounds from following.
Options
- AR ₃ ~N < R ₂ NH < R - NH ₂ < NH ₃
- BNH ₃ < R - NH ₂ < R ₂ NH < R ₃ ~N
- CR ₂ NH < R ₃ ~N < R - NH ₂ < NH ₃
- DNH ₃ < R ₃ ~N < R ₂ NH < R - NH ₂
Correct answer
B. NH ₃ < R - NH ₂ < R ₂ NH < R ₃ ~N
Step-by-step solution
The basic strength of amines is determined by the availability of nitrogen's lone pair for donation. Alkyl groups exert an inductive effect, increasing electron density on nitrogen. Based solely on this effect, basicity increases with alkyl substitution: NH ₃ In aqueous solution, solvation effects and steric hindrance become significant. The conjugate acid's stability through hydrogen bonding decreases with increased alkyl substitution: NH ₄^+ forms 4 H-bonds, RNH ₃^+ forms 3, R ₂ NH ₂^+ forms 2, and R ₃ NH ^+ form