Arrange the following in decreasing orde

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Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Amines

Question:

Arrange the following in decreasing order of the basic character in aqueous phase

(A) Ethanamine
(B) Benzeneamine
(C) Phenylmethanamine
(D) N-methylaniline

Choose the correct answer from the options given below:

Options:

(A), (C), (B), (D)

(A), (C), (D), (B)

(B), (A), (D), (C)

(C), (B), (D), (A)

Correct Answer:

(A), (C), (D), (B)

Explanation:

The correct answer is Option (2) → (A), (C), (D), (B)

Correct order of decreasing basic strength in aqueous phase:

(A) > (C) > (D) > (B)

i.e. Ethanamine > Phenylmethanamine > N-Methylaniline > Benzeneamine (Aniline)

Explanation (Kb or pKb order):

Compound	Name	Type	Reason for basicity order	Order
(A) CH₃CH₂NH₂	Ethanamine	Aliphatic 1° amine	Pure +I effect, no resonance, full solvation of conjugate acid	1
(C) C₆H₅CH₂NH₂	Phenylmethanamine	Benzylamine	+I effect dominates, phenyl not directly attached to N	2
(D) C₆H₅NHCH₃	N-Methylaniline	Aromatic 2° amine	Lone pair partially delocalized into ring, but less than aniline (steric + hyperconjugation from methyl)	3
(B) C₆H₅NH₂	Aniline (Benzeneamine)	Aromatic 1° amine	Lone pair strongly delocalized into benzene ring → least basic	4