Benzyl acetate is an ester that smells like jasmine, while ethyl butyrate is an ester with a pineapple scent. Another example of an ester with a distinct scent is methyl salicylate, which smells like wintergreen oil and is used in Vicks products.
Esters can be produced in a laboratory via a chemical reaction called esterification, which chemists carry out by combining alcohols with carboxylic acids. Benzyl acetate, for example, is produced using acetic acid and benzyl alcohol. Ethyl butyrate is derived from butyric acid and ethyl alcohol, while methyl salicylate is synthesized using salicylic acid and methyl alcohol. To carry out esterfication, chemists add heat to the appropriate carboxylic acids and alcohols in the presence of a dehydrating substance, such as concentrated sulfuric acid.
Chemistry students can carry out esterfication on a small scale using test tubes to observe the fragrances of esters. The typical procedure involves adding small amounts of the carboxylic acid, alcohol and dehydrating agent to a test tube and then placing the tube in a hot water bath for a few minutes. Esterfication is a slow process, so not much ester is produced during the experiment, which can make it hard to detect the smell of the ester over the smell of the carboxylic acid. To make it easier to smell the ester, the solution can be poured into water, causing the ester to gather in a thin layer on the surface of the water.