Reesterified

Reesterified refers to the result or process of forming an ester again from a molecule that already contains ester functionality. In organic chemistry, reesterification can mean the reformation of ester bonds on a substrate after hydrolysis or transesterification, typically by reacting carboxylic acid or acid derivatives with an alcohol (or vice versa) under catalytic conditions. The term emphasizes the re-creation of ester linkages rather than the first-time formation of ester groups.

Reesterification is common in lipid and polymer chemistry. In triglyceride chemistry, during processing or modification, ester groups can be replaced by new ester groups through reactions with different alcohols, yielding mixed or redistributed esters. In synthetic chemistry, a hydrolyzed ester can be reesterified to introduce a different alkoxy group, often under acid catalysis and with removal of water or alcohol to drive equilibrium.

Acid catalysts such as sulfuric acid or p-toluenesulfonic acid, as well as enzymatic catalysts like lipases, can promote reesterification. Reaction conditions that remove water or alcohol thereby shift equilibrium toward ester formation. Reesterification can be used to modify properties of natural esters or to produce designer esters for fragrances, plasticizers, or biodiesel feedstocks.

Reesterification is related to esterification and transesterification, but it is distinguished by its focus on forming or reforming ester groups after previous hydrolysis or exchange steps. It is also used to describe redistribution of ester groups in polyesters or triglycerides under catalytic conditions.

See also: esterification, transesterification, hydrolysis, esters, lipases.