Why is there a large difference in the boiling points of butanal and butan-1-ol ?

Explanation

Butan-1-0I has intermolecular H-bonding as shown below

Butanol has polar O-H bond due to which it shows intermolecular H-bonding which is not possible in case of butanal due to absence of polar bond. Instead of it has only weak dipole-dipole interactions. Hence, butanal has higher boiling point than butan-1-01.