Uses of Esters

Esters have many everyday uses. AQA expects you to know four: solvents, plasticisers, perfumes and food flavourings. Each use follows from their properties.Smell and volatility. Esters have pleasant, often fruity smells. Ester molecules cannot form hydrogen bonds with each other (they have no O-H group), so their boiling points are low and they evaporate easily. For example, ethyl ethanoate boils at 77 °C, while its isomer butanoic acid boils at 164 °C. Volatile, sweet-smelling esters are used in perfumes and as food flavourings; 3-methylbutyl ethanoate, for example, tastes and smells of bananas.Solvents. Esters are polar, so they dissolve many polar organic compounds, and being volatile they evaporate away quickly afterwards. Ethyl ethanoate is used as a solvent in glues, printing inks and nail varnish remover.Plasticisers. Some esters are added to polymers such as PVC to make them softer and more flexible. The plasticiser molecules fit between the polymer chains and weaken the intermolecular forces between them, so the chains can slide past each other. Over time plasticisers can escape from the plastic, which then becomes more brittle.