Ester

Esters are a class of chemical compounds and functional groups. Esters are formally formed in a condensation reaction between an alcohol and an acid in a reaction known as esterification. The most common type of esters are carboxylic acid esters (R1-C(=O)OR2), but other acids including phosphoric acid, sulfuric acid, nitric acid, or boric acid also form analogous esters. Volatile esters often have a smell and are found in perfumes, essential oils, and pheromones. Volatile esters also give many fruits their smells. Ethyl acetate and methyl acetate are important solvents, fatty acid esters form fat and lipids, and polyesters are important plastics. Cyclic esters are called lactones. The name "ester" is derived from the German Essig-Äther (literally:vinegar ether), an old name for ethyl acetate.