i) Arrange the following in increasing order of basic strength in water: C₆H₅NH₂, (C₂H₅)₂NH, (C₂H₅)₃N and NH₃.
ii) Arrange the following in increasing order of basic strength in the gas phase: C₂H₅NH₂, (C₂H₅)₂NH, (C₂H₅)₃N and CH₃NH₂.
ii) Arrange the following in increasing order of basic strength in the gas phase: C₂H₅NH₂, (C₂H₅)₂NH, (C₂H₅)₃N and CH₃NH₂.
Answer: (i) C₆H₅NH₂ < NH₃ < (C₂H₅)₃N < (C₂H₅)₂NH. (ii) CH₃NH₂ < C₂H₅NH₂ < (C₂H₅)₂NH < (C₂H₅)₃N (pure +I order, no solvation).
Solution
(i) In water:
(resonance kills aniline; hydration drops the 3° below the 2°).
(ii) In the gas phase only the inductive effect counts — basicity simply rises with alkyl substitution:
(resonance kills aniline; hydration drops the 3° below the 2°).
(ii) In the gas phase only the inductive effect counts — basicity simply rises with alkyl substitution:
CBSE Class 12 Board · 2008 · All India · Subjective