Editing Transesterification (section)

{{short description|Chemical reaction which exchanges the R groups of an alcohol and ester}}
{{Use dmy dates|date=September 2022}}

'''Transesterification''' is the process of exchanging the organic [[functional group]] R″ of an [[esters|ester]] with the organic group R' of an [[alcohols|alcohol]]. These reactions are often [[catalyst|catalyzed]] by the addition of an [[acid]] or [[base (chemistry)|base]] catalyst.<ref>{{cite journal|last1=Otera|first1=Junzo.|title=Transesterification|journal=Chemical Reviews|date=June 1993|volume=93|issue=4|pages=1449–1470|doi=10.1021/cr00020a004}}</ref> Strong acids catalyze the reaction by donating a [[proton]] to the [[carbonyl]] group, thus making it a more potent [[electrophile]]. Bases catalyze the reaction by removing a proton from the alcohol, thus making it more [[nucleophile|nucleophilic]]. The reaction can also be accomplished with the help of enzymes, particularly [[lipase]]s (one example is the lipase E.C.3.1.1.3<ref>{{Cite web|title=ENZYME – 3.1.1.3 Triacylglycerol lipase|url=https://enzyme.expasy.org/EC/3.1.1.3|access-date=2021-02-17|website=enzyme.expasy.org|publisher=[[Swiss Institute of Bioinformatics|SIB Swiss Institute of Bioinformatics]]}}</ref>).

[[Image:Transesterification.png|center|thumb|500px|{{center|'''Transesterification''': alcohol + ester → different alcohol + different ester}}]]

If the alcohol produced by the reaction can be separated from the reactants by distillation this will drive the [[Chemical equilibrium|equilibrium]] toward the products. This means that esters with larger [[alkoxy group]]s can be made from methyl or ethyl esters in high purity by heating the mixture of ester, acid/base, and large alcohol.