Carboxylic acids

Carboxylic acids are organic acids with the carboxyl functional group -COOH. This carboxyl group is highlighted in green in Figure 1. Carboxylic acids are named with the suffix -ic acid, or -oic acid, for example, salicylic acid, and benzoic acid.

The carboxyl functional group is polar, and this means that smaller carboxylic acids are usually soluble in water. Carboxylic acids are proton (H⁺) donors, which means they are Bronsted-Lowry acids. Also, they are typically weak acids, and they tend to have higher boiling points than water.

Figure 1 - The molecular structure of salicylic acid, also known as 2-hydroxybenzoic acid. The functional groups are highlighted: in green is the carboxylic acid, in yellow is the benzene ring, and in blue is the alcohol group.