Transesterification

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transesterification

[¦trans·e¦ster·ə·fə′kā·shən]
(organic chemistry)
Conversion of an organic acid ester into another ester of that same acid.

Transesterification

 

the general name for the processes of alcoholysis (1), acidolysis (2), and ester (RCOOR’) interchange (3):

(1) RCOOR’ + R”OH ⇄ RCOOR” + R’OH

(2) RCOOR’ + R”COOH ⇄ R”COOR’ + RCOOH

(3) RCOOR’ + R”COOR”’ ⇄ RCOOR’” + R”COOR’

The catalysts of transesterification are acids (HCl, HBr, and H3PO4), BF3, and salts of Zn and Co. A shift in the equilibrium toward the right is usually achieved by distillation of the more volatile alcohol (R’OH), acid (RCOOH), or ester.

Transesterification is widely used in preparative organic chemistry and the chemical industry. Thus, bis-β-hydroxyethyl terephthalate, which yields polyethylene terephthalate upon heating to 275°–290°C under vacuum, is obtained from dimethyl terephthalate and ethylene glycol. Transesterification is one of the industrial methods of producing polycarbonates.

References in periodicals archive ?
The product of the acid-pretreatment was transesterified with alkali catalyst and methanol (0.
Exhaust emissions from a Diesel engine fueled with transesterified waste olive oil, Fuel 82(11): 1311-1315.
After dissolution of the pure milk fat in hexane, the glycerides were transesterified to the corresponding methyl esters of fatty acids by a solution of potassium hydroxide in methanol.
The newly transesterified blend in such cases may tend to have a more amorphous character.
Under stressful conditions they accumulate storage lipids, mainly triglycerides, which can be transesterified to biodiesel.
The soy monomers are transesterified with a suitable glycol to increase molecular weight and generate the NOPs.
The refined fish oil was transesterified with methyl alcohol to produce biodiesel.
75] Dorado MP et al, 2003, "Exhaust emissions from a Diesel engine fueled with transesterified waste olive oil", Fuel, 82, 1311-1315.
The primary biofuels produced at a commercial scale today in the United States are ethanol, which exploits the starch resources in corn and other grains, and transesterified biodiesel from oilseed crops, such as soybeans and animal fats.
This is transesterified with glycine by the mitochondrial enzyme acyl-CoA:glycine-N-acyltransferase (glycine-Nacylase) to form 2-MBG (9).
In the simple glycolysis with excess glycol(s) the urethane groups are simply transesterified as is shown in Figure 1.