In organic chemistry, esters (Esters) are an important class of organic compounds. Esters are usually obtained by the esterification reaction between acids (which can be carboxylic acids or inorganic oxyacids) and alcohols under certain conditions.

Its structure is that the carboxyl group (-COOH) in the acid or the corresponding acidic group in the inorganic oxyacid dehydrates and condenses with the hydroxyl group (-OH) in the alcohol to form an ester structure such as -COO-. For example, acetic acid and ethanol undergo esterification reaction. The carboxyl group of acetic acid removes the hydroxyl group, and the hydroxyl group of ethanol removes the hydrogen atom. The two combine to form ethyl acetate, and at the same time produce a molecule of water.

Ester compounds exist widely in nature and daily life and have a variety of uses. The aroma of many fruits comes from the various esters contained in them, such as isoamyl acetate in bananas, which gives bananas their unique aroma. In industry, esters can be used as solvents, such as ethyl acetate, which is often used in paints, inks and other industries because of its good solubility and volatility. In addition, esters are also important intermediates in the field of organic synthesis and can be used to prepare other more complex organic compounds.