Boiling point -physical characteristics of carbonyl compound

The boiling points of aldehydes and ketones are high as compared to those of non polar compounds (hydrocarbons) or weak polar compounds (like ethers) of comparable molecular masses. Though, their boiling points are lower as compared to those of corresponding alcohols or carboxylic acids. This is since aldehydes and ketones are polar compounds having enough intermolecular dipole-dipole interactions among the opposite ends of dipoles.

Though, these dipole-dipole interactions are weaker as compared to the intermolecular hydrogen bonding in alcohols and carboxylic acids. Hence, boiling points of aldehydes and ketones are comparatively lower than the alcohols and carboxylic acids of comparable molecular masses.

Between the carbonyl compounds, ketones have little higher boiling points than the isomeric aldehydes. This is because of the existence of two electrons releasing groups around the carbonyl carbon that makes them more polar.