Arrange the following in the increasing order of their boiling points

(A) $n-C_4H_9NH_2$
(B) $(C_2H_5)_2NH$
(C) $n-C_4H_9OH$
(D) $C_2H_5N(CH_3)_2$

Choose the correct answer from the options given below:

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

The correct answer is Option (4) → (D), (B), (A), (C)

Boiling point mainly depends on hydrogen bonding strength and molecular structure.

Strength of intermolecular forces: Alcohols > Primary amines > Secondary amines > Tertiary amines

REASON

• Alcohols (–OH) form the strongest hydrogen bonding.

• Primary amines (–NH₂) can form more hydrogen bonds than secondary amines.

• Secondary amines (–NH) form fewer hydrogen bonds.

• Tertiary amines have no N–H bond, so they cannot form intermolecular hydrogen bonding.

(D) C₂H₅N(CH₃)₂
Tertiary amine → weakest intermolecular attraction → lowest boiling point

(B) (C₂H₅)₂NH
Secondary amine → moderate hydrogen bonding - Boiling point higher than tertiary amine.

(A) n-C₄H₉NH₂
Primary amine → stronger hydrogen bonding - Boiling point higher than secondary amine.

(C) n-C₄H₉OH
Alcohol → strongest hydrogen bonding → highest boiling point

D < B < A < C  is the increasing order of boiling points.