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The correct order of decreasing basic strength of the given amines is:
A
N-methylaniline > benzenamine > ethanamine > N-ethylethanamine
B
N-ethylethanamine > ethanamine > benzenamine > N-methylaniline
C
N-ethylethanamine > ethanamine > N-methylaniline > benzenamine
D
benzenamine > ethanamine > N-methylaniline > N-ethylethanamine
Explanation
Aliphatic amines are stronger bases than aromatic amines. Secondary aliphatic amine > primary aliphatic amine > secondary aromatic amine > aniline.
Detailed Solution
Aliphatic amines have localized electron pairs on nitrogen and are far stronger bases than aryl amines where the nitrogen lone pair is delocalized into the benzene ring (+R effect). Among aliphatic amines in aqueous medium, diethylamine (N-ethylethanamine, $2^\circ$) is more basic than ethylamine (ethanamine, $1^\circ$) due to combined $+I$ and steric/solvation effects. Among aromatic amines, N-methylaniline has a $+I$ methyl group that enhances electron density on N relative to benzenamine (aniline). Thus: N-ethylethanamine > ethanamine > N-methylaniline > benzenamine.
