In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R′ of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. The reaction can also be accomplished with the help of enzymes (biocatalysts) particularly lipases (E.C.188.8.131.52).
Strong acids catalyse the reaction by donating a proton to the carbonyl group, thus making it a more potent electrophile, whereas bases catalyse the reaction by removing a proton from the alcohol, thus making it more nucleophilic.
The largest scale application of transesterification is in the synthesis of polyesters. In this application diesters undergo transesterification with diols to form macromolecules. For example, dimethyl terephthalate and ethylene glycol react to form polyethylene terephthalate and methanol, which is evaporated to drive the reaction forward.
Methanolysis and biodiesel production
The reverse reaction, methanolysis, is also an example of transesterification. This process has been used to recycle polyesters into individual monomers (see plastic recycling). It is also used to convert fats (triglycerides) into biodiesel. This conversion was one of the first uses. Transesterified vegetable oil (biodiesel) was used to power heavy-duty vehicles in South Africa before World War II.
It was patented in the U.S. in the 1950s by Colgate, though Biolipid transesterification may have been discovered much earlier. In the 1940s, researchers were looking for a method to more readily produce glycerine, which was used to produce explosives for World War II. Many of the methods used today by producers and homebrewers have their origin in the original 1940s research.
Biolipid transesterification has also been recently shown by Japanese researchers to be possible using a super-critical methanol methodology, whereby high temperature, high-pressure vessels are used to physically catalyze the Biolipid/methanol reaction into fatty-acid methyl esters.
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transestérification — ● transestérification nom féminin Modification, par l action d un catalyseur alcalin, de la structure des glycérides constituant les corps gras, par échange des molécules d acides gras d une molécule à une autre … Encyclopédie Universelle
Transesterification — Ester Pour l’article homophone, voir Esther. Séquence de la fonction ester. La fonction ester est constituée d un atome de carbone l … Wikipédia en Français
Transestérification — Ester Pour l’article homophone, voir Esther. Séquence de la fonction ester. La fonction ester est constituée d un atome de carbone l … Wikipédia en Français
transesterification — peresterinimas statusas T sritis chemija apibrėžtis Vienų rūgščių liekanų esteriuose pakeitimas kitomis. atitikmenys: angl. transesterification rus. перэстерификация … Chemijos terminų aiškinamasis žodynas
transesterification — /trans euh ster euh fi kay sheuhn, tranz /, n. Chem. a reaction between an ester of one alcohol and a second alcohol to form an ester of the second alcohol and an alcohol from the original ester, as that of methyl acetate and ethyl alcohol to… … Universalium
transesterification — noun The reaction of an ester with an alcohol in order to replace the alkoxy group; it is used in the synthesis of polyesters and in the production of biodiesel … Wiktionary
transesterification — trans·es·ter·i·fi·ca·tion .tran(t)s e .ster ə fə kā shən, tranz n a reversible reaction in which one ester is converted into another (as by interchange of ester groups with an alcohol in the presence of a base) … Medical dictionary
transesterification — trans·esterification … English syllables
transesterification — |tran(t)s, raan , nz+ noun Etymology: trans + esterification : a reversible reaction in which one ester is converted into another (as by interchange of ester groups with an alcohol in the presence of a base) * * * /trans euh ster euh fi kay… … Useful english dictionary
Biodiesel production — is the act of producing the biofuel, biodiesel, through either transesterification or alcoholysis. The process involves reacting vegetable oils or animal fats catalytically with a short chain aliphatic alcohols (typically methanol or… … Wikipedia