esterne

Esterne is the plural form used in several languages for chemical esters, a class of compounds derived from carboxylic acids and alcohols. In general, esters have the functional group R-CO-O-R', where a carbonyl group is bonded to an alkoxy or aryl-oxy group. They are typically formed by condensation of a carboxylic acid and an alcohol, a reaction known as esterification, usually catalyzed by acid with water as a byproduct. Esters can also be prepared from acyl chlorides or by transesterification.

Properties of esters vary widely, but many have distinctive, often pleasant odors and are relatively volatile. They are polar compounds with a carbonyl and an adjacent C–O bond. Esters are susceptible to hydrolysis in acidic or basic media, regenerating the corresponding carboxylic acid (or carboxylate) and alcohol.

Esters have numerous applications. They are widely used as flavors and fragrance ingredients and as solvents (for example, ethyl acetate). In polymer chemistry, esters form polyesters such as polyethylene terephthalate (PET). Fatty acid methyl esters are important components of biodiesel. Esters also appear in natural products, contributing to the aromas of many fruits and flowers.

Nomenclature typically pairs the alkyl (or aryl) group from the alcohol with the acid-derived name ending in -ate (for example, methyl acetate, ethyl propanoate). In scientific literature, the term esterne may appear as a natural-language plural of ester in Scandinavian languages. Safety and handling follow standard chemical-practice guidelines, with attention to flammability and potential irritation.