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40-702: Glycerides are fatty acid esters of glycerol ; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils . Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoacids (e.g. esters of acetic acid , carbonic acid , sulfuric acid , phosphoric acid , nitric acid , xanthic acid ), but also from acids that do not contain oxygen (e.g. esters of thiocyanic acid and trithiocarbonic acid ). An example of an ester formation

80-476: A carbonyl group C=O, which is a divalent group at C atom, which gives rise to 120° C–C–O and O–C–O angles. Unlike amides , carboxylic acid esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier. Their flexibility and low polarity is manifested in their physical properties; they tend to be less rigid (lower melting point) and more volatile (lower boiling point) than

120-443: A dehydrating agent: The equilibrium constant for such reactions is about 5 for typical esters, e.g., ethyl acetate. The reaction is slow in the absence of a catalyst. Sulfuric acid is a typical catalyst for this reaction. Many other acids are also used such as polymeric sulfonic acids . Since esterification is highly reversible, the yield of the ester can be improved using Le Chatelier's principle : Reagents are known that drive

160-617: A broad array of plastics , plasticizers , resins , and lacquers , and are one of the largest classes of synthetic lubricants on the commercial market. Polyesters are important plastics, with monomers linked by ester moieties . Esters of phosphoric acid form the backbone of DNA molecules. Esters of nitric acid , such as nitroglycerin , are known for their explosive properties. There are compounds in which an acidic hydrogen of acids mentioned in this article are not replaced by an organyl, but by some other group. According to some authors, those compounds are esters as well, especially when

200-952: A combination of hyperconjugation and dipole minimization effects. The preference for the Z conformation is influenced by the nature of the substituents and solvent, if present. Lactones with small rings are restricted to the s -trans (i.e. E ) conformation due to their cyclic structure. Esters derived from carboxylic acids and alcohols are more polar than ethers but less polar than alcohols. They participate in hydrogen bonds as hydrogen-bond acceptors, but cannot act as hydrogen-bond donors, unlike their parent alcohols. This ability to participate in hydrogen bonding confers some water-solubility. Because of their lack of hydrogen-bond-donating ability, esters do not self-associate. Consequently, esters are more volatile than carboxylic acids of similar molecular weight. Esters are generally identified by gas chromatography, taking advantage of their volatility. IR spectra for esters feature an intense sharp band in

240-565: A part of metal and metalloid alkoxides , of which many hundreds are known, could be classified as esters of the corresponding acids (e.g. aluminium triethoxide ( Al(OCH 2 CH 3 ) 3 ) could be classified as an ester of aluminic acid which is aluminium hydroxide , tetraethyl orthosilicate ( Si(OCH 2 CH 3 ) 4 ) could be classified as an ester of orthosilicic acid , and titanium ethoxide ( Ti(OCH 2 CH 3 ) 4 ) could be classified as an ester of orthotitanic acid ). Esters derived from carboxylic acids and alcohols contain

280-465: A systematic review of the evidence concluded that the overall results are inconclusive. Also, interest in MCTs has been shown by endurance athletes and the bodybuilding community, but MCTs have not been found to be beneficial to exercise performance. Caprylic acid has been studied as part of a ketogenic diet to treat children with intractable epilepsy . Caprylic acid is currently being researched as

320-534: Is octanoyl , capryloyl , or caprylyl . It is a common industrial chemical, which is produced by oxidation of the C8 aldehyde . Its compounds are found naturally in the milk of various mammals and as a minor constituent of coconut oil and palm kernel oil . Two other acids are named after goats via the Latin word capra : caproic acid (C6) and capric acid (C10). Together, these three fatty acids comprise 15% of

360-684: Is γ-valerolactone . An uncommon class of esters are the orthoesters . One of them are the esters of orthocarboxylic acids. Those esters have the formula RC(OR′) 3 , where R stands for any group (organic or inorganic) and R ′ stands for organyl group. For example, triethyl orthoformate ( HC(OCH 2 CH 3 ) 3 ) is derived, in terms of its name (but not its synthesis) from esterification of orthoformic acid ( HC(OH) 3 ) with ethanol . Esters can also be derived from inorganic acids. Inorganic acids that exist as tautomers form two or more types of esters. Some inorganic acids that are unstable or elusive form stable esters. In principle,

400-539: Is a dibutylstannylene ester of lauric acid , and the Phillips catalyst CrO 2 (OSi(OCH 3 ) 3 ) 2 is a trimethoxysilyl ester of chromic acid ( H 2 CrO 4 ). The word ester was coined in 1848 by a German chemist Leopold Gmelin , probably as a contraction of the German Essigäther , " acetic ether ". The names of esters that are formed from an alcohol and an acid, are derived from

440-403: Is a signal that the body requires an input of energy in the form of food consumption. Ghrelin stimulates hunger by triggering receptors in the hypothalamus . In order to activate these receptors, ghrelin must undergo a process called acylation in which it acquires an acyl group , and caprylic acid provides this by linking at a specific serine site on ghrelin molecules. Other fatty acids in

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480-463: Is also an equilibrium process – essentially the reverse of the Fischer esterification reaction. Because an alcohol (which acts as the leaving group) and water (which acts as the nucleophile) have similar p K a values, the forward and reverse reactions compete with each other. As in transesterification, using a large excess of reactant (water) or removing one of the products (the alcohol) can promote

520-648: Is considered too hazardous and expensive for large-scale applications. Carboxylic acids are esterified by treatment with epoxides , giving β-hydroxyesters: This reaction is employed in the production of vinyl ester resin from acrylic acid . Alcohols react with acyl chlorides and acid anhydrides to give esters: The reactions are irreversible simplifying work-up . Since acyl chlorides and acid anhydrides also react with water, anhydrous conditions are preferred. The analogous acylations of amines to give amides are less sensitive because amines are stronger nucleophiles and react more rapidly than does water. This method

560-602: Is employed only for laboratory-scale procedures, as it is expensive. Trimethyloxonium tetrafluoroborate can be used for esterification of carboxylic acids under conditions where acid-catalyzed reactions are infeasible: Although rarely employed for esterifications, carboxylate salts (often generated in situ ) react with electrophilic alkylating agents , such as alkyl halides , to give esters. Anion availability can inhibit this reaction, which correspondingly benefits from phase transfer catalysts or such highly polar aprotic solvents as DMF . An additional iodide salt may, via

600-1092: Is not usually reversible. Hydrazines and hydroxylamine can be used in place of amines. Esters can be converted to isocyanates through intermediate hydroxamic acids in the Lossen rearrangement . Sources of carbon nucleophiles, e.g., Grignard reagents and organolithium compounds, add readily to the carbonyl. Glycerides Glycerides , also known as acylglycerols , are esters formed from glycerol and fatty acids , and are generally very hydrophobic. Glycerol has three hydroxyl functional groups , which can be esterified with one, two, or three fatty acids to form mono- , di- , and triglycerides . These structures vary in their fatty acid alkyl groups as they can contain different carbon numbers, different degrees of unsaturation, and different configurations and positions of olefins. Vegetable oils and animal fats contain mostly triglycerides, but are broken down by natural enzymes ( lipases ) into mono and diglycerides and free fatty acids and glycerol. Soaps are formed from

640-602: Is one illustrative example. The carbonylation of methanol yields methyl formate , which is the main commercial source of formic acid . The reaction is catalyzed by sodium methoxide : In hydroesterification , alkenes and alkynes insert into the O−H bond of carboxylic acids. Vinyl acetate is produced industrially by the addition of acetic acid to acetylene in the presence of zinc acetate catalysts: Vinyl acetate can also be produced by palladium -catalyzed reaction of ethylene, acetic acid , and oxygen : Silicotungstic acid

680-464: Is the substitution reaction between a carboxylic acid ( R−C(=O)−OH ) and an alcohol ( R'−OH ), forming an ester ( R−C(=O)−O−R' ), where R stands for any group (typically hydrogen or organyl) and R ′ stands for organyl group. Organyl esters of carboxylic acids typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones . They perform as high-grade solvents for

720-503: Is used as an acyl-transfer catalyst . Another method for the dehydration of mixtures of alcohols and carboxylic acids is the Mitsunobu reaction : Carboxylic acids can be esterified using diazomethane : Using this diazomethane, mixtures of carboxylic acids can be converted to their methyl esters in near quantitative yields, e.g., for analysis by gas chromatography . The method is useful in specialized organic synthetic operations but

760-421: Is used as an algicide, bactericide, fungicide, and herbicide in nurseries, greenhouses, garden centers, and interiors, and on ornamentation. Products containing caprylic acid are formulated as soluble concentrate/liquids and ready-to-use liquids. Caprylic acid plays an important role in the body's regulation of energy input and output, a function which is performed by the hormone ghrelin . The sensation of hunger

800-494: Is used in the production of ethyl acetate from acetaldehyde . Esters are less reactive than acid halides and anhydrides. As with more reactive acyl derivatives, they can react with ammonia and primary and secondary amines to give amides, although this type of reaction is not often used, since acid halides give better yields. Esters can be converted to other esters in a process known as transesterification . Transesterification can be either acid- or base-catalyzed, and involves

840-410: Is used to manufacture ethyl acetate by the alkylation of acetic acid by ethylene: The Tishchenko reaction involves disproportionation of an aldehyde in the presence of an anhydrous base to give an ester. Catalysts are aluminium alkoxides or sodium alkoxides. Benzaldehyde reacts with sodium benzyloxide (generated from sodium and benzyl alcohol ) to generate benzyl benzoate . The method

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880-506: The Finkelstein reaction , catalyze the reaction of a recalcitrant alkyl halide. Alternatively, salts of a coordinating metal, such as silver, may improve the reaction rate by easing halide elimination. Transesterification , which involves changing one ester into another one, is widely practiced: Like the hydrolysation, transesterification is catalysed by acids and bases. The reaction is widely used for degrading triglycerides , e.g. in

920-573: The organyl parts of the carboxylic acid and the alcohol, respectively, and R can be a hydrogen in the case of esters of formic acid . For example, butyl acetate (systematically butyl ethanoate), derived from butanol and acetic acid (systematically ethanoic acid) would be written CH 3 CO 2 (CH 2 ) 3 CH 3 . Alternative presentations are common including BuOAc and CH 3 COO(CH 2 ) 3 CH 3 . Cyclic esters are called lactones , regardless of whether they are derived from an organic or inorganic acid. One example of an organic lactone

960-400: The reaction product . Esters are common in organic chemistry and biological materials, and often have a pleasant characteristic, fruity odor. This leads to their extensive use in the fragrance and flavor industry. Ester bonds are also found in many polymers . The classic synthesis is the Fischer esterification , which involves treating a carboxylic acid with an alcohol in the presence of

1000-420: The systematic name octanoic acid or C8 Acid , is a saturated fatty acid , medium-chain fatty acid (MCFA). It has the structural formula H 3 C−(CH 2 ) 6 − COOH , and is a colorless oily liquid that is minimally soluble in water with a slightly unpleasant rancid-like smell and taste. Salts and esters of octanoic acid are known as octanoates or caprylates . The name of the related acyl group

1040-425: The aroma of many fruits, including apples , durians , pears , bananas , pineapples , and strawberries . Several billion kilograms of polyesters are produced industrially annually, important products being polyethylene terephthalate , acrylate esters , and cellulose acetate . Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as

1080-418: The corresponding amides . The p K a of the alpha-hydrogens on esters of carboxylic acids is around 25 (alpha-hydrogen is a hydrogen bound to the carbon adjacent to the carbonyl group (C=O) of carboxylate esters). Many carboxylic acid esters have the potential for conformational isomerism , but they tend to adopt an S - cis (or Z ) conformation rather than the S - trans (or E ) alternative, due to

1120-465: The dehydration of mixtures of alcohols and carboxylic acids. One example is the Steglich esterification , which is a method of forming esters under mild conditions. The method is popular in peptide synthesis , where the substrates are sensitive to harsh conditions like high heat. DCC ( dicyclohexylcarbodiimide ) is used to activate the carboxylic acid to further reaction. 4-Dimethylaminopyridine (DMAP)

1160-494: The fatty acids in goat milk fat. Caprylic acid is used commercially in the production of esters used in perfumery and also in the manufacture of dyes. Caprylic acid is an antimicrobial pesticide used as a food contact surface sanitizer in commercial food handling establishments on dairy equipment, food processing equipment, breweries, wineries, and beverage processing plants. It is also used as disinfectant in health care facilities and public places. In addition, caprylic acid

1200-408: The first carbon atom of the organyl group replacing acidic hydrogen, is replaced by another atom from the group 14 elements ( Si , Ge , Sn , Pb ); for example, according to them, trimethylstannyl acetate (or trimethyltin acetate) CH 3 COOSn(CH 3 ) 3 is a trimethylstannyl ester of acetic acid , and dibutyltin dilaurate (CH 3 (CH 2 ) 10 COO) 2 Sn((CH 2 ) 3 CH 3 ) 2

1240-467: The formulation of certain pharmaceuticals. The most common forms of acylglycerol are triglycerides , having high caloric value and usually yielding twice as much energy per gram as carbohydrate. An acylglyceride linkage is the covalent bond between the organic acid groups (such as fatty acid ) and one of the three hydroxyl groups of glycerol . Caprylic acid Caprylic acid (from Latin capra  'goat'), also known under

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1280-494: The forward reaction. Basic hydrolysis of esters, known as saponification , is not an equilibrium process; a full equivalent of base is consumed in the reaction, which produces one equivalent of alcohol and one equivalent of a carboxylate salt. The saponification of esters of fatty acids is an industrially important process, used in the production of soap. Esterification is a reversible reaction. Esters undergo hydrolysis under acidic and basic conditions. Under acidic conditions,

1320-448: The other hand, more frequently named using the systematic IUPAC name, based on the name for the acid followed by the suffix -oate . For example, the ester hexyl octanoate, also known under the trivial name hexyl caprylate , has the formula CH 3 (CH 2 ) 6 CO 2 (CH 2 ) 5 CH 3 . The chemical formulas of organic esters formed from carboxylic acids and alcohols usually take the form RCO 2 R' or RCOOR', where R and R' are

1360-468: The parent alcohol and the parent acid, where the latter may be organic or inorganic. Esters derived from the simplest carboxylic acids are commonly named according to the more traditional, so-called " trivial names " e.g. as formate, acetate, propionate, and butyrate, as opposed to the IUPAC nomenclature methanoate, ethanoate, propanoate, and butanoate. Esters derived from more complex carboxylic acids are, on

1400-465: The production of fatty acid esters and alcohols. Poly(ethylene terephthalate) is produced by the transesterification of dimethyl terephthalate and ethylene glycol: A subset of transesterification is the alcoholysis of diketene . This reaction affords 2-ketoesters. Alkenes undergo carboalkoxylation in the presence of metal carbonyl catalysts. Esters of propanoic acid are produced commercially by this method: A preparation of methyl propionate

1440-437: The range 1730–1750 cm assigned to ν C=O . This peak changes depending on the functional groups attached to the carbonyl. For example, a benzene ring or double bond in conjunction with the carbonyl will bring the wavenumber down about 30 cm. Esters are widespread in nature and are widely used in industry. In nature, fats are, in general, triesters derived from glycerol and fatty acids . Esters are responsible for

1480-406: The reaction is the reverse reaction of the Fischer esterification . Under basic conditions, hydroxide acts as a nucleophile, while an alkoxide is the leaving group. This reaction, saponification , is the basis of soap making. The alkoxide group may also be displaced by stronger nucleophiles such as ammonia or primary or secondary amines to give amides (ammonolysis reaction): This reaction

1520-419: The reaction of an ester with an alcohol. Unfortunately, because the leaving group is also an alcohol, the forward and reverse reactions will often occur at similar rates. Using a large excess of the reactant alcohol or removing the leaving group alcohol (e.g. via distillation ) will drive the forward reaction towards completion, in accordance with Le Chatelier's principle . Acid-catalyzed hydrolysis of esters

1560-733: The reaction of glycerides with sodium hydroxide . The product of the reaction is glycerol and salts of fatty acids. Fatty acids in the soap emulsify the oils in dirt, enabling the removal of oily dirt with water. Partial glycerides are esters of glycerol with fatty acids, where not all the hydroxyl groups are esterified. Since some of their hydroxyl groups are free their molecules are polar . Partial glycerides may be monoglycerides (two hydroxyl groups free) or diglycerides (one hydroxyl group free). Short chain partial glycerides are more strongly polar than long chain partial glycerides, and have excellent solvent properties for many hard-to-solubilize drugs, making them valuable as excipients in improving

1600-439: The same position have similar effects on hunger. The acyl chloride of caprylic acid is used in the synthesis of perfluorooctanoic acid . Caprylic acid is taken as a dietary supplement . In the body, caprylic acid would be found as octanoate, or unprotonated caprylic acid. Some studies have shown that medium-chain triglycerides (MCTs) can help in the process of excess calorie burning, and thus weight loss ; however,

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