Continued oxidation of aldehydes leads to carboxylic acids:




Complete oxidation of alcohols to acids is easy and almost inevitable, unless the volatile aldehyde intermediates are vaporized as fast as they form. Carboxylic acids are extensively hydrogen bonded in the liquid, and therefore have higher boiling points than aldehydes. The acid group is often written -COOH, and R-COOH represents a general carboxylic acid.

The smaller carboxylic acids are named in a straightforward way, like the related aldehydes (in each case, the systematic name is given in parentheses) :