In condensation reactions between an alkanol and an alkanoic acid, a water molecule is removed to form an ester. So, to break the ester back down into an alkanol and an alkanoic acid, a water molecule must be added. This is known as hydrolysis.
Ester hydrolysis occurs very slowly, and can be catalyzed by refluxing the ester with either dilute mineral acid (acid hydrolysis) or excess dilute alkali (alkaline hydrolysis). The process of refluxing involves heating a mixture for a chemical reaction to occur while condensing/cooling the vapours evaporated (using a condenser) and returning them to the mixture as a liquid again. The apparatus for refluxing looks like this:
In the acid hydrolysis of ethyl ethanoate (CH3COOC2H5), ethanol and ethanoic acid are formed:
In alkaline hydrolysis, the alkanoic acid is formed first. The acid is then neutralized by the excess alkali, forming the salt of the acid (a carboxylate salt). The other product will be the alkanol:
Alkaline hydrolysis is sometimes referred to as saponification, but this is more accurately used in the manufacturing of soaps (which will be covered in a later post).
The products of the reaction (in either form of ester hydrolysis) are separated by distillation.