How many of the following amines are engaged in intermolecular association due to hydrogen bonding between the nitrogen of one molecule and the hydrogen of another?
Ethanamine, N-Methylmethanamine, N,N-Dimethylmethanamine, Aniline, N,N-Dimethylaniline, N-Methylaniline, Propan-1-amine
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 5
An amine molecule can hydrogen bond to another molecule of the same amine only if it has a hydrogen atom on nitrogen. Primary (–NH2) and secondary (>NH) amines have such hydrogen atoms; tertiary amines have none, so they show no intermolecular association.
Associated (primary and secondary amines):
Ethanamine (primary amine)
N-Methylmethanamine (secondary amine)
Aniline (primary amine)
N-Methylaniline (secondary amine)
Propan-1-amine (primary amine)
Not associated:
N,N-Dimethylmethanamine — tertiary amine; no H on nitrogen.
N,N-Dimethylaniline — tertiary amine; no H on nitrogen.
Associated: 5 amines.
NCERT (2026-27 edition):
9.5 Physical Properties – “Primary and secondary amines are engaged in intermolecular association due to hydrogen bonding between nitrogen of one and hydrogen of another molecule. … Tertiary amines do not have intermolecular association due to the absence of hydrogen atom available for hydrogen bond formation.”