Esters are
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
s derived by reacting an
oxoacidAn oxoacid is an acid that contains oxygen. To be more specific, it is an acid that:#contains oxygen#contains at least one other element#has at least one hydrogen atom bound to oxygen#forms an ion by the loss of one or more protons....
with a
hydroxylA hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...
compound such as an
alcoholIn chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
or
phenolIn organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group bonded directly to an aromatic hydrocarbon group...
. Esters are usually derived from an inorganic acid or
organic acidAn organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...
in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group, and most commonly from
carboxylic acidCarboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
s and
alcoholIn chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s. That is, esters are formed by
condensingA condensation reaction is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction; other possible small molecules lost are hydrogen chloride,...
an acid with an alcohol.
Esters are ubiquitous. Most naturally occurring fats and oils are the
fatty acidIn chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
esters of
glycerolGlycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...
. Esters with low molecular weight are commonly used as fragrances and found in
essential oilAn essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...
s and
pheromoneA pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
s. Phosphoesters form the backbone of
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
molecules. Nitrate esters, such as
nitroglycerin, are known for their explosive properties, while
polyesterPolyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
s are important
plasticA plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
s, with monomers linked by ester moieties.
IUPAC nomenclature of Esters
Ester names are derived from the parent alcohol and the parent acid, where the latter may be an organic or an inorganic acid. 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 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
caprylateCaprylic acid is the common name for the eight-carbon saturated fatty acid known by the systematic name octanoic acid. It is found naturally in the milk of various mammals, and it is a minor constituent of coconut oil and palm kernel oil...
, has the formula CH
3(CH
2)
6CO
2(CH
2)
5CH
3.
The chemical formulas of organic esters are typically written in the format of RCO
2R', where R and R' are the hydrocarbon parts of the carboxylic acid and alcohol, respectively. For example
butyl acetaten-Butyl acetate, also known as butyl ethanoate, is an organic compound commonly used as a solvent in the production of lacquers and other products. It is also used as a synthetic fruit flavoring in foods such as candy, ice cream, cheeses, and baked goods. Butyl acetate is found in many types of...
, derived from
butanoln-Butanol or n-butyl alcohol or normal butanol is a primary alcohol with a 4-carbon structure and the molecular formula C4H9OH. Its isomers include isobutanol, 2-butanol, and tert-butanol...
and
acetic acidAcetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
would be written CH
3CO
2C
4H
9. Alternative presentations are common including BuOAc and CH
3COOC
4H
9.
Cyclic esters are called
lactoneIn chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...
s, regardless of whether they are derived from an organic or an inorganic acid. One example of a (organic) lactone is
gamma-valerolactonegamma-Valerolactone is an organic compound with the formula C5H8O2. This clear liquid is one of the more common lactones. It is a structural isomer of delta-valerolactone. Because of its herbal odor, it is used in the perfume and flavor industries....
.
Orthoesters
An uncommon class of organic esters are the
orthoesterIn organic chemistry, an orthoester is a functional group containing three alkoxy groups attached to one carbon atom, i.e. with the general formula RC3. The name can also refer to any organic compound that contains this functional group. An example of an orthoester is ethyl orthoacetate, CH3C3,...
s, which have the formula RC(OR')
3. Triethylorthoformate (HC(OC
2H
5)
3) is derived, in terms of its name (but not its synthesis) from
orthoformic acidOrthoformic acid or methanetriol is a hypothetical compound with the formula HC3. In this molecule, the central carbon is bound to one hydrogen and three hydroxyl groups....
(HC(OH)
3) and
ethanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
.
"Inorganic esters"
Ester is a general term for the product derived from the condensation of an acid and an alcohol. Thus, the nomenclature extends to inorganic oxo acids, e.g.
phosphoric acidPhosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...
,
sulfuric acidSulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
,
nitric acidNitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
and
boronic acidA boronic acid is an alkyl or aryl substituted boric acid containing a carbon–boron bond belonging to the larger class of organoboranes. Boronic acids act as Lewis acids. Their unique feature is that they are capable of forming reversible covalent complexes with sugars, amino acids, hydroxamic...
. Cyclic esters are hence also called
lactoneIn chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...
s. For example,
triphenyl phosphateTriphenyl phosphate is the chemical compound with the formula OP3. This colourless solid is the ester of phosphoric acid and phenol. It is used as a plasticizer and a fire retardant....
is the ester derived from
phosphoric acidPhosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...
and
phenolPhenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...
. Organic carbonates, such as
ethylene carbonateEthylene carbonate is an ester of ethylene glycol and carbonic acid. At room temperature ethylene carbonate is a transparent crystalline solid, practically odorless and colorless, and somewhat soluble in water. In the liquid state Ethylene carbonate is an ester of ethylene glycol and carbonic...
, are derived from
carbonic acidCarbonic acid is the inorganic compound with the formula H2CO3 . It is also a name sometimes given to solutions of carbon dioxide in water, because such solutions contain small amounts of H2CO3. Carbonic acid forms two kinds of salts, the carbonates and the bicarbonates...
and
ethylene glycolEthylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...
.
Structure and bonding
Esters contain a
carbonylIn organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....
center, which gives rise to 120°C-C-O and O-C-O angles. Unlike
amideIn chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...
s, 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 the corresponding amides. The pKa of the alpha-hydrogens on esters is around 25.
Physical properties and characterization
Esters are more polar than ethers but less polar than alcohols. They participate in
hydrogen bondA hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond...
s 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 acidCarboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
s of similar molecular weight.
Characterization and analysis
Esters are usually identified by gas chromatography, taking advantage of their volatility. IR spectra for esters feature an intense sharp band in the range 1730–1750 cm
−1 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 conjugation with the carbonyl will bring the wavenumber down about 30 cm
−1.
Applications and occurrence
Esters are widespread in nature and are widely used in industry. In nature,
fatFats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
s are, in general, triesters derived from
glycerolGlycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...
and
fatty acidIn chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s. Esters are responsible for the aroma of many fruits, including apples, pears, bananas, pineapples, and strawberries. Several billion kilograms of polyesters are produced industrially annually, important products being
polyethylene terephthalatePolyethylene terephthalate , commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination...
, acrylate esters, and
cellulose acetateCellulose acetate , first prepared in 1865, is the acetate ester of cellulose. Cellulose acetate is used as a film base in photography, as a component in some adhesives, and as a frame material for eyeglasses; it is also used as a synthetic fiber and in the manufacture of cigarette filters and...
.
Preparation
Esterification is the general name for a
chemical reactionA chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
in which two reactants (typically an alcohol and an acid) form an ester as the
reaction productProduct are formed during chemical reactions as reagents are consumed. Products have lower energy than the reagents and are produced during the reaction according to the second law of thermodynamics. The released energy comes from changes in chemical bonds between atoms in reagent molecules and...
. Esters are common in organic chemistry and biological materials, and often have a characteristic pleasant, fruity odor. This leads to their extensive use in the fragrance and flavor industry. Ester bonds are also found in many
polymerA polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s.
Esterification of carboxylic acids
The classic synthesis is the
Fischer esterificationFischer esterification or Fischer–Speier esterification is a special type of esterification by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. The reaction was first described by Emil Fischer and Arthur Speier in 1895. Most carboxylic acids are suitable for the...
, which involves treating a carboxylic acid with an alcohol in the presence of a dehydrating agent:
- RCO2H + R'OH RCO2R' + H2O
The equilibrium constant for such reactions is about 5 for typical esters, e.g., ethyl acetate. but the reaction is slow in the absence of a catalyst.
Sulfuric acidSulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
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 principleIn chemistry, Le Chatelier's principle, also called the Chatelier's principle, can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chatelier and sometimes Karl Ferdinand Braun who discovered it independently...
:
- using the alcohol in large excess (i.e., as a solvent)
- using a dehydrating agent: Sulfuric acid not only catalyzes the reaction but sequesters water (a reaction product). Other drying agents like molecular sieves can also be used.
- removal of water by physical means such as distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
as a low-boiling azeotropeAn azeotrope is a mixture of two or more liquids in such a ratio that its composition cannot be changed by simple distillation. This occurs because, when an azeotrope is boiled, the resulting vapor has the same ratio of constituents as the original mixture....
s with tolueneToluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...
, in conjunction with a Dean-Stark apparatusFor the video game character, see Wild Arms 5thumb|right|A Dean-Stark apparatus in use; aluminum foil is used to reduce radiative heat lossesThe Dean-Stark apparatus or Dean-Stark receiver or distilling trap is a piece of laboratory glassware used in synthetic chemistry to collect water from a...
.
Reagents are known that drive the dehydration of mixtures of alcohols and carboxylic acids. One example is the
Steglich esterificationThe Steglich esterification is a variation of an esterfication with dicyclohexylcarbodiimide as a coupling reagent and 4-dimethylaminopyridine as a catalyst. The reaction was first described by Wolfgang Steglich in 1978...
, which is a method of forming esters under mild conditions. The method is popular in
peptide synthesisIn organic chemistry, peptide synthesis is the production of peptides, which are organic compounds in which multiple amino acids are linked via amide bonds which are also known as peptide bonds...
, where the substrates are sensitive to harsh conditions like high heat. DCC (
dicyclohexylcarbodiimideN,N-Dicyclohexylcarbodiimide is an organic compound with chemical formula C13H22N2 whose primary use is to couple amino acids during artificial peptide synthesis. Under standard conditions, it exists in the form of white crystals with a heavy, sweet odor. The low melting point of this material...
) is used to activate the carboxylic acid to further reaction. DMAP (
4-dimethylaminopyridine4-Dimethylaminopyridine is a derivative of pyridine with the chemical formula 2NC5H4N. This colourless solid is a useful nucleophilic catalyst for a variety of reactions such as esterifications with anhydrides, the Baylis-Hillman reaction, hydrosilylations, tritylation, the Steglich...
) is used as an acyl-transfer catalyst.
Another method for the dehydration of mixtures of alcohols and carboxylic acids is the
Mitsunobu reactionThe Mitsunobu reaction is an organic reaction that converts an alcohol into a variety of functional groups, such as an ester, using triphenylphosphine and an azodicarboxylate such as diethyl azodicarboxylate or diisopropyl azodicarboxylate . The alcohol undergoes an inversion of stereochemistry...
:
- RCO2H + R'OH + P(C6H5)3 + R2N2 → RCO2R' + OP(C6H5)3 + R2N2H2
Carboxylic acids can be esterified using
diazomethaneDiazomethane is the chemical compound CH2N2. It is the simplest of diazo compounds. In the pure form at room temperature, it is a extremely sensitive explosive yellow gas, thus it is almost universally used as a solution in diethyl ether...
:
- RCO2H + CH2N2 → RCO2CH3 + N2
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 is considered too expensive for large scale applications.
Alcoholysis of acyl chlorides and acid anhydrides
Alcohols react with
acyl chlorideIn organic chemistry, an acyl chloride is an organic compound with the functional group -CO-Cl. Their formula is usually written RCOCl, where R is a side chain. They are usually considered to be reactive derivatives of carboxylic acids. A specific example of an acyl chloride is acetyl chloride,...
s and acid anhydrides to give esters:
- RCOCl + R'OH → RCO2R' + HCl
- (RCO)2O + R'OH → RCO2R' + RCO2H
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
amideIn chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...
s are less sensitive because amines are stronger nucleophiles and react more rapidly. This method is employed only for laboratory-scale procedures, as it is expensive.
Alkylation of carboxylate salts
Although not widely employed for esterifications, salts of carboxylate anions can be alkylating agent with alkyl halides to give esters. In the case that an alkyl chloride is used, an iodide salt can catalyze the reaction (
Finkelstein reactionThe Finkelstein reaction, named for the German chemist Hans Finkelstein , is an SN2 reaction that involves the exchange of one halogen atom for another...
). The carboxylate salt is often generated
in situ. In difficult cases, the silver carboxylate may be used, since the silver ion coordinates to the halide aiding its departure and improving the reaction rate. This reaction can suffer from anion availability problems and, therefore, can benefit from the addition of
phase transfer catalystIn chemistry, a phase transfer catalyst or PTC is a catalyst that facilitates the migration of a reactant from one phase into another phase where reaction occurs. Phase transfer catalysis is a special form of heterogeneous catalysis. Ionic reactants are often soluble in an aqueous phase but...
s or highly polar aprotic solvents such as
DMFDimethylformamide is an organic compound with the formula 2NCH. Commonly abbreviated as DMF , this colourless liquid is miscible with water and the majority of organic liquids. DMF is a common solvent for chemical reactions...
.
Transesterification
TransesterificationIn 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...
, which involves changing one ester into another one, is widely practiced:
- RCO2R' + CH3OH → RCO2CH3 + R'OH
Like the hydrolysis reaction, transesterification is catalysed by acids and bases. The reaction is widely used for degrading
triglycerideA triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....
s, e.g. in the production of fatty acid esters and alcohols. Poly(ethyleneterephthalate) is produced by the transesterification of
dimethyl terephthalateDimethyl terephthalate is an organic compound with the formula C6H42. It is the diester formed from terephthalic acid and methanol. It is a white solid that melts to give a distillable colourless liquid.-Production:...
and ethylene glycol:
-
- (C6H4)(CO2CH3)2 + 2 C2H4(OH)2 → 1/n {(C6H4)(CO2)2(C2H4)}n + 2 CH3OH
Carbonylation
Alkenes undergo "hydroesterification" in the presence of
metal carbonylMetal carbonyls are coordination complexes of transition metals with carbon monoxide ligands. These complexes may be homoleptic, that is containing only CO ligands, such as nickel carbonyl , but more commonly metal carbonyls contain a mix of ligands, such as Re3Cl...
catalysts. Esters of
propionic acidPropanoic acid is a naturally occurring carboxylic acid with chemical formula CH3CH2COOH. It is a clear liquid with a pungent odor...
are produced commercially by this method:
- C2H4 + ROH + CO → C2H5CO2R
The carbonylation of
methanolMethanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
yields
methyl formateMethyl formate, also called methyl methanoate, is the methyl ester of formic acid. The simplest example of an ester, it is a clear liquid with an ethereal odor, high vapor pressure, and low surface tension.-Production:...
, which the main commercial source of
formic acidFormic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...
. The reaction is catalyzed by
sodium methoxideSodium methoxide is a chemical compound, with formula CH3ONa. This colourless solid, which is formed by the deprotonation of methanol, is a widely used reagent in industry and the laboratory...
:
- CH3OH + CO → CH3O2CH
Addition of carboxylic acids to alkenes
In the presence of
palladiumPalladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
-based catalysts, ethylene,
acetic acidAcetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
, and
oxygenOxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
react to give
vinyl acetateVinyl acetate is an organic compound with the formula CH3COOCH=CH2. A colorless liquid with a pungent odor, it is the precursor to polyvinyl acetate, an important polymer in industry.-Production:...
:
- C2H4 + CH3CO2H + 1/2 O2 → C2H3O2CCH3 + H2O
Direct routes to this same ester are not possible because vinyl alcohol is unstable.
Other methods
- Favorskii rearrangement
The Favorskii rearrangement , named for the Russian chemist Alexei Yevgrafovich Favorskii, is most principally a rearrangement of cyclopropanones and α-halo ketones which leads to carboxylic acid derivatives. In the case of cyclic α-halo ketones, the Favorski rearrangement constitutes a ring...
of α-haloketones in presence of base
- Baeyer-Villiger oxidation
The Baeyer–Villiger oxidation is an organic reaction in which a ketone is oxidized to an ester by treatment with peroxy acids or hydrogen peroxide. Key features of the Baeyer–Villiger oxidation are its stereospecificity and predictable regiochemistry...
of ketones with peroxides.
- Pinner reaction
The Pinner reaction is an organic reaction of a nitrile with an alcohol under acid catalysis for instance hydrochloric acid. The product formed is the hydrochloric acid salt of an imino ester or an alkyl imidate, which sometimes is called a Pinner salt...
of nitrileA nitrile is any organic compound that has a -C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, one example being super glue .Inorganic compounds containing the -C≡N group are not called...
s with an alcohol.
Reactions
Esters react primarily at one of two locations, the carbonyl or the carbon adjacent the carbonyl group. The carbonyl is weakly electrophilic and is attacked by strong nucleophilies (amines, alkoxides, hydride sources, organolithium compounds, etc.). The C-H bonds adjacent to the carbonyl are weakly acidic but undergo deprotonation with strong bases. This process is the one that usually initiates condensation reactions.
Addition of nucleophiles at carbonyl
Esterification is a reversible reaction. Esters undergo
hydrolysisHydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
under acid and basic conditions. Under acidic conditions, the reaction is the reverse reaction of the
Fischer esterificationFischer esterification or Fischer–Speier esterification is a special type of esterification by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. The reaction was first described by Emil Fischer and Arthur Speier in 1895. Most carboxylic acids are suitable for the...
. Under basic conditions,
hydroxideHydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and a hydrogen atom held together by a covalent bond, and carrying a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, as a ligand, a nucleophile, and a...
acts as a nucleophile, while an alkoxide is the leaving group. This reaction,
saponificationSaponification is a process that produces soap, usually from fats and lye. In technical terms, saponification involves base hydrolysis of triglycerides, which are esters of fatty acids, to form the sodium salt of a carboxylate. In addition to soap, such traditional saponification processes...
, is the basis of soap making.
The alkoxide group may also be displaced by stronger nucleophiles such as
ammoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
or primary or secondary
amineAmines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s to give
amideIn chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...
s:
-
- RCO2R' + NH2R" → RCONHR" + R'OH
This reaction is not usually reversible. Hydrazines and hydroxylamine can be used in place of amines. Esters can be converted to
isocyanateIsocyanate is the functional group of elements –N=C=O , not to be confused with the cyanate functional group which is arranged as –O–C≡N or with isocyanide, R-N≡C. Any organic compound which contains an isocyanate group may also be referred to in brief as an isocyanate. An isocyanate may have more...
s through intermediate
hydroxamic acidA hydroxamic acid is a class of chemical compounds sharing the same functional group in which an hydroxylamine is inserted into a carboxylic acid. Its general structure is R-CO-NH-OH, with an R as an organic residue, a CO as a carbonyl group, and a hydroxylamine as NH2-OH. They are used as metal...
s in the
Lossen rearrangementThe Lossen rearrangement is the conversion of a hydroxamic acid to an isocyanate via the formation of an O-acyl, sulfonyl, or phosphoryl intermediate hydroxamic acid O-derivative and then conversion to its conjugate base. Here, 4-Toluenesulfonyl chloride is used to form a sulfonyl O-derivative...
.
Sources of carbon nucleophiles, e.g., Grignard reagents and organolithium compounds, add readily to the carbonyl.
Reduction
Compared to ketones and aldehydes, esters are relatively resistant to reduction. The introduction of catalytic hydrogenation in the early part of the 20th century was a breakthrough; esters of fatty acids are hydrogenated to
fatty alcoholFatty alcohols are aliphatic alcohols consisting of a chain of 8 to 22 carbon atoms. Fatty alcohols usually have even number of carbon atoms and a single alcohol group attached to the terminal carbon. Some are unsaturated and some are branched...
s.
-
- RCO2R' + 2 H2 → RCH2OH + R'OH
A typical catalyst is copper chromite. Prior to the development of catalytic hydrogenation, esters were reduced on a large scale using the
Bouveault-Blanc reductionThe Bouveault-Blanc reduction is a chemical reaction in which an ester is reduced to primary alcohols using absolute ethanol and sodium metal.This reaction is an inexpensive and large-scale alternative to lithium aluminium hydride reduction of esters....
. This method, which is largely obsolete, uses sodium in the presence of proton sources.
Especially for fine chemical syntheses,
lithium aluminium hydrideLithium aluminium hydride, commonly abbreviated to LAH or known as LithAl, is an inorganic compound with the chemical formula LiAlH4. It was discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters,...
is used to reduce esters to two primary alcohols. The related reagent sodium borohydride is slow in this reaction. DIBAH reduces esters to aldehydes.
Claisen condensation and related reactions
As for ketones and aldehydes, the hydrogen atoms on the carbon adjacent ("α to") the carboxyl group in esters are sufficiently acidic to undergo deprotonation, which in turn leads to a variety of useful reactions. Deprotonation requires relatively strong bases, such as
alkoxideAn alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands...
s. Deprotonation gives a nucleophilic enolate, which can further react, e.g., the
Claisen condensationThe Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone...
and its intramolecular equivalent, the
Dieckmann condensationThe Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give β-ketoesters. It is named after the German chemist Walter Dieckmann . The equivalent intermolecular reaction is the Claisen condensation....
. This conversion is exploited in the
malonic ester synthesisThe malonic ester synthesis is a chemical reaction where diethyl malonate or another ester of malonic acid is alkylated at the carbon alpha to both carbonyl groups, and then converted to a substituted acetic acid. The major drawback of malonic ester synthesis is that the alkylation stage can also...
, wherein the diester of
malonic acidMalonic acid is a dicarboxylic acid with structure CH22. The ionised form of malonic acid, as well as its esters and salts, are known as malonates. For example, diethyl malonate is malonic acid's ethyl ester...
reacts with an electrophile (e.g., alkyl halide), and is subsequently decarboxylated.
Other reactions
- Phenyl esters react to hydroxyarylketones in the Fries rearrangement
The Fries rearrangement, named for the German chemist Karl Theophil Fries, is a rearrangement reaction of a phenyl ester to a hydroxy aryl ketone by catalysis of Lewis acids.It involves migration of an acyl group of phenyl ester to benzene ring.- Mechanism:...
.
- Specific esters are functionalized with an α-hydroxyl group in the Chan rearrangement
The Chan rearrangement is a chemical reaction that involves rearranging an acyloxy acetate in the presence of a strong base to a 2-hydroxy-3-keto-ester .This procedure was rediscovered and employed in the Holton Taxol total synthesis....
.
- Esters with β-hydrogen atoms can be converted to alkenes in ester pyrolysis
Ester pyrolysis in organic chemistry is a vacuum pyrolysis reaction converting esters containing a β-hydrogen atom into the corresponding carboxylic acid and the alkene...
.
Protecting groups
As a class, esters serve as
protecting groupA protecting group or protective group is introduced into a molecule by chemical modification of a functional group in order to obtain chemoselectivity in a subsequent chemical reaction...
s for
carboxylic acidCarboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
s. Protecting a carboxylic acid is useful in peptide synthesis, to prevent self-reactions of the bifunctional
amino acidAmino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s. Methyl and ethyl esters are commonly available for many amino acids; the
t-butyl ester tends to be more expensive. However,
t-butyl esters are particularly useful because, under strongly acidic conditions, the
t-butyl esters undergo elimination to give the carboxylic acid and isobutene, simplifying work-up.
List of ester odorants
Many esters have distinctive fruit-like odors, which has led to their commonplace use in artificial flavorings and fragrances.
| Ester Name |
Structure |
Odor or occurrence |
| Allyl hexanoate Allyl hexanoate is a colorless to pale yellow clear liquid.-Uses:Allyl hexanoate is employed principally in the formulation of pineapple flavors but it can also be used for peach and apricot essences and for apple blossom, peach blossom, and wisteria perfume compositions. Allyl caproate is an...
|
|
pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
|
Benzyl acetateBenzyl acetate is an organic compound with the molecular formula C9H10O2. It is the ester formed by condensation of benzyl alcohol and acetic acid....
|
|
pearThe pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
, strawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
, jasmineJasminum , commonly known as jasmines, is a genus of shrubs and vines in the olive family . It contains around 200 species native to tropical and warm temperate regions of the Old World...
|
| Bornyl acetate |
 |
pinePines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
|
Butyl butyrateButyl butyrate, or butyl butanoate, is an organic compound that is an ester formed by the condensation of butyric acid and n-butanol. It is a clear, colorless liquid that is insoluble in water, but miscible with ethanol and diethyl ether. Its refractive index is 1.406 at 20 °C.-Aroma:Like other...
|
 |
pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
|
| Ethyl acetate Ethyl acetate is the organic compound with the formula CH3COOCH2CH3. This colorless liquid has a characteristic sweet smell and is used in glues, nail polish removers, and cigarettes...
|
|
nail polish remover, model A scale model is a physical model, a representation or copy of an object that is larger or smaller than the actual size of the object, which seeks to maintain the relative proportions of the physical size of the original object. Very often the scale model is used as a guide to making the object in...
paintPaint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
, model airplaneModel aircraft are flying or non-flying models of existing or imaginary aircraft using a variety of materials including plastic, diecast metal, polystyrene, balsa wood, foam and fibreglass...
glueAn adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
|
| Ethyl butyrate Ethyl butyrate, also known as ethyl butanoate, or butyric ether, is an ester with the chemical formula CH3CH2CH2COOCH2CH3. It is soluble in propylene glycol, paraffin oil, and kerosene. It has a fruity odor, similar to pineapple.-Uses:...
|
 |
bananaBanana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
, pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
, strawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
|
| Ethyl hexanoate |
 |
pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
, waxy-green banana |
| Ethyl cinnamate Ethyl cinnamate is the ester of cinnamic acid and ethanol. It is present in the essential oil of cinnamon. Pure ethyl cinnamate has a "fruity and balsamic odor, reminiscent of cinnamon with an amber note"....
|
 |
cinnamonCinnamon is a spice obtained from the inner bark of several trees from the genus Cinnamomum that is used in both sweet and savoury foods...
|
| Ethyl formate Ethyl formate is an ester formed when ethanol reacts with formic acid . It is also known as ethyl methanoate because formic acid is also known as methanoic acid. Ethyl formate has the characteristic smell of rum and is also partially responsible for the flavor of raspberries.-Exposure:Ethyl...
|
 |
lemonThe lemon is both a small evergreen tree native to Asia, and the tree's ellipsoidal yellow fruit. The fruit is used for culinary and non-culinary purposes throughout the world – primarily for its juice, though the pulp and rind are also used, mainly in cooking and baking...
, rumRum is a distilled alcoholic beverage made from sugarcane by-products such as molasses, or directly from sugarcane juice, by a process of fermentation and distillation. The distillate, a clear liquid, is then usually aged in oak barrels...
, strawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
|
| Ethyl heptanoate Ethyl heptanoate is the ester resulting from the condensation of heptanoic acid and ethanol. It is used in the flavor industry because of its odor that is similar to grape....
|
 |
apricot The apricot, Prunus armeniaca, is a species of Prunus, classified with the plum in the subgenus Prunus. The native range is somewhat uncertain due to its extensive prehistoric cultivation.- Description :...
, cherryThe cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
, grapeA grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...
, raspberryThe raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves...
|
| Ethyl isovalerate |
 |
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
|
| Ethyl lactate Ethyl lactate, also known as lactic acid ethyl ester, is a monobasic ester formed from lactic acid and ethanol, commonly used as a solvent. This compound is considered biodegradable and can be used as a water-rinsible degreaser. Ethyl lactate is found naturally in small quantities in a wide variety...
|
 |
butterButter is a dairy product made by churning fresh or fermented cream or milk. It is generally used as a spread and a condiment, as well as in cooking applications, such as baking, sauce making, and pan frying...
, creamCream is a dairy product that is composed of the higher-butterfat layer skimmed from the top of milk before homogenization. In un-homogenized milk, over time, the lighter fat rises to the top. In the industrial production of cream this process is accelerated by using centrifuges called "separators"...
|
| Ethyl nonanoate |
 |
grape A grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...
|
| Ethyl pentanoate Ethyl pentanoate, also commonly known as ethyl valerate, is an organic compound used in flavors. It is an ester with the molecular formula C7H14O2. This colorless liquid is poorly soluble in water but miscible with organic solvents....
|
 |
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
|
| Geranyl acetate |
 |
geraniumPelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...
|
| Geranyl butyrate |
 |
cherryThe cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
|
| Geranyl pentanoate |
|
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
|
| Isobutyl acetate The chemical compound isobutyl acetate, also known as 2-methylpropyl ethanoate or β-methylpropyl acetate, is a common solvent. It is produced from the esterification of isobutanol with acetic acid. It is used as a solvent for lacquer and nitrocellulose...
|
 |
cherryThe cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
, raspberryThe raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves...
, strawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
|
| Isobutyl formate Isobutyl formate is an organic ester with the chemical formula C5H10O2. It is formed by diluting isobutanol with methanoic acid. It is used as a flavor and fragrance ingredient because of its odor which is sweet, ethereal, and slightly fruity....
|
|
raspberryThe raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves...
|
Isoamyl acetateIsoamyl acetate, also known as isopentyl acetate, is an organic compound that is the ester formed from isoamyl alcohol and acetic acid. It is a colorless liquid that is only slightly soluble in water, but very soluble in most organic solvents...
|
 |
pearThe pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
, bananaBanana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
(flavoring in Pear dropA pear drop is a British boiled sweet made from sugar and flavourings. The classic pear drop is a combination of half pink and half yellow in a pear-shaped drop about the size of a thumbnail, although they are more commonly found in packets containing separate yellow drops and pink drops in roughly...
s) |
| Isopropyl acetate Isopropyl acetate is an ester, an organic compound which is the product of condensation of acetic acid and isopropanol. It is a clear, colorless liquid with a characteristic fruity odor....
|
 |
fruity |
Linalyl acetateLinalyl acetate is a naturally occurring phytochemical found in many flowers and spice plants. It is one of the principal components of the essential oils of bergamot and lavender. Chemically, it is the acetate ester of linalool, and the two often occur in conjunction.Synthetic linalyl acetate is...
|
 |
lavenderThe lavenders are a genus of 39 species of flowering plants in the mint family, Lamiaceae. An Old World genus, distributed from Macaronesia across Africa, the Mediterranean, South-West Asia, Arabia, Western Iran and South-East India...
, sageSalvia officinalis is a small, perennial, evergreen subshrub, with woody stems, grayish leaves, and blue to purplish flowers. It is a member of the family Lamiaceae and is native to the Mediterranean region, though it has naturalized in many places throughout the world...
|
| Linalyl butyrate |
 |
peachThe peach tree is a deciduous tree growing to tall and 6 in. in diameter, belonging to the subfamily Prunoideae of the family Rosaceae. It bears an edible juicy fruit called a peach...
|
| Linalyl formate |
 |
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
, peachThe peach tree is a deciduous tree growing to tall and 6 in. in diameter, belonging to the subfamily Prunoideae of the family Rosaceae. It bears an edible juicy fruit called a peach...
|
| Methyl acetate Methyl acetate, also known as MeOAc, acetic acid methyl ester or methyl ethanoate, is a carboxylate ester with the formula CH3COOCH3. It is normally a flammable liquid with a characteristic, pleasant smell like certain glues or nail polish removers. Methyl acetate has characteristics very similar...
|
 |
glueThis is a list of various types of glue. Historically, the term "glue" only referred to protein colloids prepared from animal flesh. The meaning has been extended to refer to any fluid adhesive....
|
Methyl anthranilateMethyl anthranilate, also known as MA, methyl 2-aminobenzoate or carbomethoxyaniline, is an ester of anthranilic acid. Its chemical formula is C8H9NO2.-Chemical properties:...
|
 |
grape A grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...
, jasmineJasminum , commonly known as jasmines, is a genus of shrubs and vines in the olive family . It contains around 200 species native to tropical and warm temperate regions of the Old World...
|
| Methyl benzoate Methyl benzoate is an ester with the chemical formula C6H5COOCH3. It is formed by the condensation of methanol and benzoic acid, in presence of a strong acid such as hydrochloric acid. It is a colorless liquid that is poorly soluble in water, but miscible with organic solvents.-Reactions:Methyl...
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 |
fruity, ylang ylang, feijoaAcca sellowiana, a species of flowering plant in the myrtle family, Myrtaceae, is native to the highlands of southern Brazil, Colombia, Uruguay, and northern Argentina. It is widely cultivated as a garden plant and fruiting tree in New Zealand, and can be found as a garden plant in Australia and...
|
| Methyl butyrate Methyl butyrate, also known under the systematic name methyl butanoate, is the methyl ester of butyric acid. Like most esters, it has a fruity odour, in this case resembling apples or pineapples. At room temperature, it is a colourless liquid with low solubility in water, upon which it floats to...
(methyl butanoate) |
|
pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
, appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
, strawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
|
Methyl cinnamateMethyl cinnamate is the methyl ester of cinnamic acid and is a white or transparent solid with a strong, aromatic odor. It is found naturally in a variety of plants, including in fruits, like strawberry, and some culinary spices, such as Sichuan pepper and some varieties of basil...
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 |
strawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
|
| Methyl pentanoate (methyl valerate) |
 |
flowerA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
y |
| Methyl phenylacetate Methyl phenylacetate is an organic compound that is the ester formed from methanol and phenylacetic acid, with the structural formula C6H5CH2COOCH3. It is a clear colorless liquid that is only slightly soluble in water, but very soluble in most organic solvents.Methyl phenylacetate has a strong...
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 |
honey Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...
|
Methyl salicylateMethyl salicylate is a natural product of many species of plants. Some of the plants which produce it are called wintergreens, hence the common name.-Botanical background:...
(oil of wintergreen) |
 |
Modern root beerRoot beer is a carbonated, sweetened beverage, originally made using the root of a sassafras plant as the primary flavor. Root beer, popularized in North America, comes in two forms: alcoholic and soft drink. The historical root beer was analogous to small beer in that the process provided a drink...
, wintergreenWintergreen is a group of plants. Wintergreen once commonly referred to plants that continue photosynthesis throughout the winter...
, GermoleneGermolene is a brand name used on a range of antiseptic products produced by the Bayer company, which in 1999 bought the brand from the then-Smithkline Beecham...
and RalgexRalgex Spray is a spray designed to sooth painful muscles and joints in humans when applied to the skin. There is also Ralgex cream available which is used for the same purpose...
ointments (UK) |
| Nonyl caprylate |
 |
orangeAn orange—specifically, the sweet orange—is the citrus Citrus × sinensis and its fruit. It is the most commonly grown tree fruit in the world....
|
Octyl acetateOctyl acetate, or octyl ethanoate, is an ester that is formed from octanol and acetic acid.Octyl acetate can be synthesized by a condensation reaction:-Use:...
|
 |
fruity-orangeAn orange—specifically, the sweet orange—is the citrus Citrus × sinensis and its fruit. It is the most commonly grown tree fruit in the world....
|
| Octyl butyrate |
 |
parsnipThe parsnip is a root vegetable related to the carrot. Parsnips resemble carrots, but are paler than most carrots and have a sweeter taste, especially when cooked. The buttery, slightly spicy, sweet flavor of cooked mature parsnips is reminiscent of butterscotch, honey, and subtle cardamom...
|
| Amyl acetate Amyl acetate is an organic compound and an ester with the chemical formula CH3COO[CH2]4CH3 and the molecular weight 130.19 g/mol. It has a scent similar to bananas and apples which is not detectable by all people. The compound is the condensation product of acetic acid and 1-pentanol...
(pentyl acetate) |
 |
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
, bananaBanana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
|
| Pentyl butyrate Pentyl butyrate, also known as pentyl butanoate or amyl butyrate, is an ester that is formed when pentanol is reacted with butyric acid, usually in the presence of sulfuric acid as a catalyst. This ester has a smell reminiscent of pear or apricot. This chemical is used as an additive in cigarettes....
(amyl butyrate) |
 |
apricot The apricot, Prunus armeniaca, is a species of Prunus, classified with the plum in the subgenus Prunus. The native range is somewhat uncertain due to its extensive prehistoric cultivation.- Description :...
, pearThe pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
, pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
|
| Pentyl hexanoate (amyl caproate) |
 |
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
, pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
|
| Pentyl pentanoate Pentyl pentanoate is an ester used in dilute solution to replicate the scent or flavour of apple, and sometimes pineapple. It is referred to as pentyl valerate or amyl pentanoate using classical nomenclature....
(amyl valerate) |
 |
appleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
|
| Propyl acetate The chemical compound propyl acetate, also known as propyl ethanoate, is a common solvent. This clear, colourless liquid is known by its characteristic odour of pears. Due to this fact, it is commonly used as a flavouring additive...
|
 |
pearThe pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
|
| Propyl hexanoate |
|
blackberryThe blackberry is an edible fruit produced by any of several species in the Rubus genus of the Rosaceae family. The fruit is not a true berry; botanically it is termed an aggregate fruit, composed of small drupelets. The plants typically have biennial canes and perennial roots. Blackberries and...
, pineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
, cheeseCheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms....
, wineWine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...
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| Propyl isobutyrate |
 |
rumRum is a distilled alcoholic beverage made from sugarcane by-products such as molasses, or directly from sugarcane juice, by a process of fermentation and distillation. The distillate, a clear liquid, is then usually aged in oak barrels...
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| Terpenyl butyrate |
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cherryThe cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
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