Esters are usually synthesized from an alcohol and an acid, most frequently, a carboxylic acid. In some cases, an epoxide is used instead of the alcohol; or an acid halide or anhydride replaces the ...

Carboxylic acids can undergo reduction reactions. Reduction is the opposite of oxidation. For example, ethanoic acid (CH 3 COOH) can be formed by the oxidation of ethanol as shown below.