What distinguishes carboxylic acids from other functional groups?

Carboxylic acids are uniquely characterized by the presence of a carbonyl group (C=O) that is directly bonded to a hydroxyl group (-OH), forming the carboxyl functional group (-COOH). This specific arrangement differentiates them from other functional groups. The carbonyl group in carboxylic acids is not just located anywhere in the molecule; it is always at the terminal position, contributing to the distinct properties of these acids, such as their ability to donate protons (H+) in aqueous solutions, making them acidic.

The presence of the carbonyl at the end of the molecule is crucial because it defines the structure and reactivity of carboxylic acids compared to other compounds that might have carbonyl groups situated elsewhere or possess entirely different functional groups. This terminal position is integral in the definition of carboxylic acids, reinforcing their identity as a distinct class within organic compounds.