There are many equilibrium reactions that yield water as a co-product. It is the co-produced water that prevents a high yield of product being obtained. The removal of the water is necessary to drive the reaction to completion and this is done using Dean-Stark apparatus. The reaction is carried out under reflux in a solvent which is less dense than water to form an azeotrope. The apparatus allows the water to be separated from the condensed azeotrope preventing it from returning to the reaction mixture.