Chemistry – Organic chemistry - Naming organic compounds | e-Consult

Esters have a characteristic sweet, often fruity, smell due to their molecular structure and the intermolecular forces between ester molecules.

The ester functional group (COOR) contains a polar carbonyl group (C=O) and an alkyl group (R or R'). The carbonyl group is polar, and the oxygen atom carries a partial negative charge. This polarity allows for dipole-dipole interactions between ester molecules. These dipole-dipole interactions are stronger than the London dispersion forces alone.

The strength of the intermolecular forces influences the volatility of the ester. Esters with stronger dipole-dipole interactions have higher boiling points and lower vapor pressures. However, even at room temperature, some ester molecules are constantly undergoing vibrational motion, and some molecules have enough kinetic energy to overcome the intermolecular forces and escape into the gas phase. These volatile ester molecules are what we perceive as smell. The specific odor depends on the structure of the ester; different alkyl groups (R and R') contribute different scents.