Esterification


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

esterification

[e‚ster·ə·fə′kā·shən]
(organic chemistry)
A chemical reaction whereby esters are formed.

Esterification

 

the production of esters by reacting alcohols with acids. For example, carboxylic acids are esterified through the reaction

Esterification is a reversible reaction; water reacts with esters to form the parent compounds (seeHYDROLYSIS).

The position of the equilibrium in esterification depends on the nature and amount of the acid and alcohol used. For example, when ethyl alcohol and acetic acid are combined in equimolar proportions, the equilibrium is established after two-thirds of the alcohol and acid have been converted to the ester (ethyl acetate). The temperature has a great effect on the rate at which maximum esterification is attained. Thus, in the previous example, only 55 percent of the maximum is formed at room temperature in 368 days, but 55.7 percent is formed at 100°C in 32 hours, and 66 percent is formed at 150°C in 24 hours. The reaction is also accelerated by the addition of strong acids, for it increases the concentration of hydronium ions, which are catalysts of esterification. According to the law of mass action, in order to increase the yield of the ester, either the concentration of one of the reactants must be increased or one of the products (ester or water) must be removed from the reaction vessel as it is formed. In the latter case, compounds that form azeotropic mixtures with water are sometimes added to the reaction mixture in order to facilitate the removal by distillation.

Between 1877 and 1879, N. A. Menshutkin established that primary alcohols undergo esterification the most readily and that tertiary alcohols undergo esterification with the greatest difficulty. In 1938 the American chemists D. Roberts and H. Urey used isotopically labeled compounds (tracers) to show that the hydroxyl group is split from the acid molecule in esterification, as shown in the reaction

Of the various methods for producing esters, esterification is the simplest and most convenient method, and it has the greatest practical importance. Esterification is one of the best studied and most commonly used organic reactions; it was first studied by P. Berthelot in 1862 and 1863.

Esterification is common in living cells and is important because of the formation of ester bonds between individual nucleotide molecules in nucleic acids. These bonds link the phosphoric radical attached to the fifth carbon of the carbohydrate pentose in one mononucleotide with the alcohol group attached to the third carbon of the pentose of another mononucleotide. The formation of the bond is catalyzed by aminoacyl-RNA synthetases, which are specific enzymes of the ligase class. The reaction of cyclization with the loss of pyrophosphate in the formation of cyclic nucleotides is also essentially an esterification that occurs between the acid and alcohol groups within a single molecule. This reaction is accomplished by means of the specific enzymes adenylate cyclase and guanylidate cyclase.

E. A. POLENOV and E. P. FEDENKO

References in periodicals archive ?
FT1R spectra of the esterification samples are very similar and there are no significant differences among them.
Of all the methods available, the only effective ones turned out to be esterification with fatty acid chlorides and transesterification with methyl esters of fatty acids.
In this process, the first stage esterification was at 40[degrees]C uses 0.
For example, HMP is an enteric polymer manufactured from the esterification of hypromellose with phthalic anhydride.
While proprietary, it can be disclosed that the esterification was performed by the addition of methanol with acid to catalyze the esterification reaction.
1] that is attributed to cellulose esterification via the anhydride functionalities (3-5), (9), (10) of MSO-2.
8; a polyester polyol obtained by esterification of building blocks having ester-forming functional groups wherein at least 30% weight of the building blocks is comprised of linear or branched alk(en)yl or alk(en)ylene groups with at least 4 carbon atoms per ester-forming functional group, the polyester polyol has a hydroxy value above 280 mg KOH/g and a hydroxy functionality of at least 2, an isocyanate-functional crosslinker, and a volatile organic diluent, wherein at least 60% weight of the volatile organic diluent comprises alk(en)yl or alk(en)ylene groups having at least 4 carbon atoms, wherein the non-volatile content of the coating composition is higher than 50% weight based on the total composition.
Walters said, is that unprocessed cholesterol can be toxic to cells and requires fatty acid-mediated modification to render it safe in a process called esterification.
She showcased her project titled "Dual Chamber Tubular Reactor for Continuous Trans esterification of Waste Cooking Oil" at the Rio+20 Summit organised by the United Nations Conference on Sustainable Development, said a press release issued by the institute on Monday.
For esterification tests, oil with acidity exceeding 2% was poured into a thermostatically controlled three-neck flask with an addition of methanol (18%) and catalyst (1.
The degree of esterification is also shown in Table 3, and the values found are similar, identifying the homogeneous group of high methoxyl pectin with an average DE of 72.
of Science, Japan) and Nishikido (Asahi Kasei Corporation, Japan) synthesize the fundamental literature on esterification and transesterification in organic synthesis from 1990 onwards.