Which among the following has highest boiling point?

We compare the boiling points of four organic compounds with similar molecular weights.

A) $$CH_3CH_2CH_2CH_3$$ (Butane): Non-polar alkane. Only weak London dispersion forces. Boiling point: $$-0.5°C$$.

B) $$CH_3CH_2CH_2CH_2OH$$ (1-Butanol): Contains an $$-OH$$ group capable of strong hydrogen bonding. Boiling point: $$117.7°C$$.

C) $$CH_3CH_2CH_2CHO$$ (Butanal): Aldehyde with a polar $$C=O$$ group, but no H-bonding with itself (no O-H or N-H). Only dipole-dipole interactions. Boiling point: $$75°C$$.

D) $$C_2H_5-O-C_2H_5$$ (Diethyl ether): Polar but cannot form hydrogen bonds with itself. Boiling point: $$34.6°C$$.

The order of boiling points is: Butanol > Butanal > Diethyl ether > Butane.

1-Butanol has the highest boiling point due to strong intermolecular hydrogen bonding. The answer is Option B) $$CH_3CH_2CH_2CH_2OH$$.