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In organic chemistry, an aldehyde () is an
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
containing a
functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the r ...
with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are common and play important roles in the technology and biological spheres.


Structure and bonding

Aldehydes feature a carbon center that is connected by a double bond to oxygen and a single bond to hydrogen and single bond to a third substituent, which is carbon or, in the case of formaldehyde, hydrogen. The central carbon is often described as being sp2- hybridized. The aldehyde group is somewhat
polar Polar may refer to: Geography Polar may refer to: * Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates *Polar climate, the cli ...
. The C=O bond length is about 120-122 picometers.


Physical properties and characterization

Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water,
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
and acetaldehyde completely so. The volatile aldehydes have pungent odors. Aldehydes can be identified by spectroscopic methods. Using IR spectroscopy, they display a strong ''ν''CO band near 1700 cm−1. In their 1H NMR spectra, the formyl hydrogen center absorbs near ''δ''H 9.5 to 10, which is a distinctive part of the spectrum. This signal shows the characteristic coupling to any protons on the α carbon with a small coupling constant typically less than 3.0 Hz. The 13C NMR spectra of aldehydes and ketones gives a suppressed (weak) but distinctive signal at ''δ''C 190 to 205.


Applications and occurrence

Important aldehydes and related compounds. The aldehyde group (or formyl group) is colored red. From the left: (1)
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
and (2) its trimer
1,3,5-trioxane 1,3,5-Trioxane, sometimes also called trioxane or trioxin, is a chemical compound with molecular formula CHO. It is a white, highly water-soluble solid with a chloroform-like odor. It is a stable cyclic trimer of formaldehyde, and one of the t ...
, (3) acetaldehyde and (4) its enol vinyl alcohol, (5)
glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
(pyranose form as α--glucopyranose), (6) the flavorant
cinnamaldehyde Cinnamaldehyde is an organic compound with the formula(C9H8O) C6H5CH=CHCHO. Occurring naturally as predominantly the ''trans'' (''E'') isomer, it gives cinnamon its flavor and odor. It is a phenylpropanoid that is naturally synthesized by the shi ...
, (7) retinal, which forms with opsins potoreceptors, and (8) the vitamin pyridoxal.


Naturally occurring aldehydes

Traces of many aldehydes are found in essential oils and often contribute to their favorable odours, e.g.
cinnamaldehyde Cinnamaldehyde is an organic compound with the formula(C9H8O) C6H5CH=CHCHO. Occurring naturally as predominantly the ''trans'' (''E'') isomer, it gives cinnamon its flavor and odor. It is a phenylpropanoid that is naturally synthesized by the shi ...
, cilantro, and vanillin. Possibly because of the high reactivity of the formyl group, aldehydes are not common in several of the natural building blocks: amino acids, nucleic acids, lipids. Most sugars, however, are derivatives of aldehydes. These aldoses exist as hemiacetals, a sort of masked form of the parent aldehyde. For example, in aqueous solution only a tiny fraction of glucose exists as the aldehyde.


Synthesis

There are several methods for preparing aldehydes, but the dominant technology is
hydroformylation Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon ...
.Bertleff, W.; Roeper, M. and Sava, X. (2003) "Carbonylation" in ''Ullmann’s Encyclopedia of Industrial Chemistry'', Wiley-VCH: Weinheim. Illustrative is the generation of
butyraldehyde Butyraldehyde, also known as butanal, is an organic compound with the formula CH3(CH2)2CHO. This compound is the aldehyde derivative of butane. It is a colorless flammable liquid with an unpleasant smell. It is miscible with most organic solvent ...
by hydroformylation of propene: :H2 + CO + CH3CH=CH2 → CH3CH2CH2CHO


Oxidative routes

Aldehydes are commonly generated by alcohol oxidation. In industry, formaldehyde is produced on a large scale by oxidation of methanol. Oxygen is the reagent of choice, being "green" and cheap. In the laboratory, more specialized oxidizing agents are used, but chromium(VI) reagents are popular. Oxidation can be achieved by heating the alcohol with an acidified solution of potassium dichromate. In this case, excess dichromate will further oxidize the aldehyde to a carboxylic acid, so either the aldehyde is distilled out as it forms (if volatile) or milder reagents such as PCC are used. : + CH3(CH2)9OH → CH3(CH2)8CHO + H2O Oxidation of primary alcohols to form aldehydes can be achieved under milder, chromium-free conditions by employing methods or reagents such as
IBX acid 2-Iodoxybenzoic acid (IBX) is an organic compound used in organic synthesis as an oxidizing agent. This periodinane is especially suited to oxidize alcohols to aldehydes. IBX is prepared from 2-iodobenzoic acid, potassium bromate, and sulfuric ...
,
Dess–Martin periodinane Dess–Martin periodinane (DMP) is a chemical reagent used in the Dess–Martin oxidation, oxidizing primary alcohols to aldehydes and secondary alcohols to ketones. This periodinane has several advantages over chromium- and DMSO-based oxidants ...
, Swern oxidation, TEMPO,. Another oxidation route significant in industry is the Wacker process, whereby ethylene is oxidized to acetaldehyde in the presence of copper and palladium catalysts (acetaldehyde is also produced on a large scale by the hydration of acetylene). On the laboratory scale, α-hydroxy acids are used as
precursors Precursor or Precursors may refer to: *Precursor (religion), a forerunner, predecessor ** The Precursor, John the Baptist Science and technology * Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of unr ...
to prepare aldehydes via
oxidative Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
cleavage.


Specialty methods


Common reactions

Aldehydes participate in many reactions. From the industrial perspective, important reactions are (a) condensations, e.g., to prepare plasticizers and polyols, and (b) reduction to produce alcohols, especially "oxo-alcohols". From the biological perspective, the key reactions involve addition of nucleophiles to the formyl carbon in the formation of imines (oxidative deamination) and hemiacetals (structures of aldose sugars).


Acid-base reactions

Because of resonance stabilization of the conjugate base, an α-hydrogen in an aldehyde is weakly acidic, with a p''K''a near 17. This acidification is attributed to (i) the electron-withdrawing quality of the formyl center and (ii) the fact that the conjugate base, an enolate anion, delocalizes its negative charge. The formyl proton itself does not readily undergo deprotonation.


Enolization

Aldehydes (except those without an alpha carbon, or without protons on the alpha carbon, such as formaldehyde and benzaldehyde) can exist in either the keto or the
enol In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene ( olefin) with a hydroxyl group attached to one end of the alkene double bond (). T ...
tautomer. Keto–enol tautomerism is catalyzed by either acid or base. Usually the enol is the minority tautomer, but it is more reactive. The enolization typically reverses several times per second.


Reduction

The formyl group can be readily reduced to a primary alcohol (−CH2OH). Typically this conversion is accomplished by catalytic hydrogenation either directly or by transfer hydrogenation. Stoichiometric reductions are also popular, as can be effected with sodium borohydride.


Oxidation

The formyl group readily oxidizes to the corresponding carboxyl group (−COOH). The preferred oxidant in industry is oxygen or air. In the laboratory, popular oxidizing agents include potassium permanganate, nitric acid,
chromium(VI) oxide Chromium trioxide (also known as chromium(VI) oxide or chromic anhydride) is an inorganic compound with the formula CrO3. It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name. This compound is a dark-purple s ...
, and chromic acid. The combination of manganese dioxide,
cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...
, acetic acid and methanol will convert the aldehyde to a methyl
ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...
. Another oxidation reaction is the basis of the ''silver-mirror test''. In this test, an aldehyde is treated with Tollens' reagent, which is prepared by adding a drop of sodium hydroxide solution into silver nitrate solution to give a precipitate of silver(I) oxide, and then adding just enough dilute
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...
solution to redissolve the precipitate in aqueous ammonia to produce g(NH3)2sup>+ complex. This reagent converts aldehydes to carboxylic acids without attacking carbon–carbon double bonds. The name ''silver-mirror test'' arises because this reaction produces a precipitate of silver, whose presence can be used to test for the presence of an aldehyde. A further oxidation reaction involves Fehling's reagent as a test. The Cu2+ complex ions are reduced to a red-brick-coloured Cu2O precipitate. If the aldehyde cannot form an enolate (e.g., benzaldehyde), addition of strong base induces the Cannizzaro reaction. This reaction results in disproportionation, producing a mixture of alcohol and carboxylic acid.


Nucleophilic addition reactions

Nucleophiles add readily to the carbonyl group. In the product, the carbonyl carbon becomes sp3-hybridized, being bonded to the nucleophile, and the oxygen center becomes protonated: : RCHO + Nu → RCH(Nu)O : RCH(Nu)O + H+ → RCH(Nu)OH In many cases, a water molecule is removed after the addition takes place; in this case, the reaction is classed as an additionelimination or additioncondensation reaction. There are many variations of nucleophilic addition reactions.


Oxygen nucleophiles

In the acetalisation reaction, under acidic or basic conditions, an alcohol adds to the carbonyl group and a proton is transferred to form a hemiacetal. Under acidic conditions, the hemiacetal and the alcohol can further react to form an acetal and water. Simple hemiacetals are usually unstable, although cyclic ones such as
glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
can be stable. Acetals are stable, but revert to the aldehyde in the presence of acid. Aldehydes can react with water to form hydrates, R−CH(OH)2. These diols are stable when strong electron withdrawing groups are present, as in chloral hydrate. The mechanism of formation is identical to hemiacetal formation.


Nitrogen nucleophiles

In alkylimino-de-oxo-bisubstitution, a primary or secondary amine adds to the carbonyl group and a proton is transferred from the nitrogen to the oxygen atom to create a
carbinolamine In organic chemistry, a hemiaminal (also carbinolamine) is a functional group or type of chemical compound that has a hydroxyl group and an amine attached to the same carbon atom: . R can be hydrogen or an alkyl group. Hemiaminals are intermedia ...
. In the case of a primary amine, a water molecule can be eliminated from the carbinolamine intermediate to yield an imine or its trimer, a
hexahydrotriazine Triazinanes are a class of nitrogen-containing heterocycles. The parent molecules' molecular formula is . They exist in three isomeric forms, 1,3,5-triazinanes being common. The triazinanes have six-membered cyclohexane-like ring but with ...
This reaction is catalyzed by acid. Hydroxylamine (NH2OH) can also add to the carbonyl group. After the elimination of water, this results in an oxime. An
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...
derivative of the form H2NNR2 such as hydrazine (H2NNH2) or 2,4-dinitrophenylhydrazine can also be the nucleophile and after the elimination of water, resulting in the formation of a
hydrazone Hydrazones are a class of organic compounds with the structure . They are related to ketones and aldehydes by the replacement of the oxygen =O with the = functional group. They are formed usually by the action of hydrazine on ketones or aldehy ...
, which are usually orange crystalline solids. This reaction forms the basis of a test for aldehydes and ketones.


Carbon nucleophiles

The cyano group in HCN can add to the carbonyl group to form
cyanohydrin In organic chemistry, a cyanohydrin or hydroxynitrile is a functional group found in organic compounds in which a cyano and a hydroxy group are attached to the same carbon atom. The general formula is , where R is H, alkyl, or aryl. Cyanohyd ...
s, R−CH(OH)CN. In this reaction the CN ion is the nucleophile that attacks the partially positive carbon atom of the carbonyl group. The mechanism involves a pair of electrons from the carbonyl-group double bond transferring to the oxygen atom, leaving it single-bonded to carbon and giving the oxygen atom a negative charge. This intermediate ion rapidly reacts with H+, such as from the HCN molecule, to form the alcohol group of the cyanohydrin. Organometallic compounds, such as organolithium reagents, Grignard reagents, or acetylides, undergo nucleophilic addition reactions, yielding a substituted alcohol group. Related reactions include
organostannane addition Organostannane addition reactions comprise the nucleophilic addition of an allyl-, allenyl-, or propargylstannane to an aldehyde, imine, or, in rare cases, a ketone. The reaction is widely used for carbonyl allylation. Organostannane addition to ...
s, Barbier reactions, and the
Nozaki–Hiyama–Kishi reaction The Nozaki–Hiyama–Kishi reaction is a nickel/chromium coupling reaction forming an alcohol from the reaction of an aldehyde with an allyl or vinyl halide. In their original 1977 publication, Tamejiro Hiyama and Hitoshi Nozaki reported on a c ...
. In the
aldol reaction The aldol reaction is a means of forming carbon–carbon bonds in organic chemistry. Discovered independently by the Russian chemist Alexander Borodin in 1869 and by the French chemist Charles-Adolphe Wurtz in 1872, the reaction combines two ...
, the metal enolates of ketones,
ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...
s,
amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it i ...
s, and carboxylic acids add to aldehydes to form β-hydroxycarbonyl compounds ( aldols). Acid or base-catalyzed dehydration then leads to α,β-unsaturated carbonyl compounds. The combination of these two steps is known as the aldol condensation. The Prins reaction occurs when a nucleophilic
alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic ...
or alkyne reacts with an aldehyde as electrophile. The product of the Prins reaction varies with reaction conditions and substrates employed.


Bisulfite reaction

Aldehydes characteristically form "addition compounds" with sodium bisulfite: : RCHO + → This reaction is used as a test for aldehydes.


More complex reactions


Dialdehydes

A dialdehyde is an organic chemical compound with two aldehyde groups. The nomenclature of dialdehydes have the ending ''-dial'' or sometimes ''-dialdehyde''. Short aliphatic dialdehydes are sometimes named after the
diacid In organic chemistry, a dicarboxylic acid is an organic compound containing two carboxyl groups (). The general molecular formula for dicarboxylic acids can be written as , where R can be aliphatic or aromatic. In general, dicarboxylic acids show ...
from which they can be derived. An example is butanedial, which is also called succinaldehyde (from succinic acid).


Biochemistry

Some aldehydes are substrates for aldehyde dehydrogenase
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s which metabolize aldehydes in the body. There are toxicities associated with some aldehydes that are related to neurodegenerative disease, heart disease, and some types of
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
.


Examples of aldehydes

*
Formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
(methanal) * Acetaldehyde (ethanal) * Propionaldehyde (propanal) *
Butyraldehyde Butyraldehyde, also known as butanal, is an organic compound with the formula CH3(CH2)2CHO. This compound is the aldehyde derivative of butane. It is a colorless flammable liquid with an unpleasant smell. It is miscible with most organic solvent ...
(butanal) * Isovaleraldehyde * Benzaldehyde (phenylmethanal) *
Cinnamaldehyde Cinnamaldehyde is an organic compound with the formula(C9H8O) C6H5CH=CHCHO. Occurring naturally as predominantly the ''trans'' (''E'') isomer, it gives cinnamon its flavor and odor. It is a phenylpropanoid that is naturally synthesized by the shi ...
* Vanillin * Tolualdehyde * Furfural *
Retinaldehyde Retinal (also known as retinaldehyde) is a polyene chromophore. Retinal, bound to proteins called opsins, is the chemical basis of visual phototransduction, the light-detection stage of visual perception (vision). Some microorganisms use retina ...
*
Glycolaldehyde Glycolaldehyde is the organic compound with the formula . It is the smallest possible molecule that contains both an aldehyde group () and a hydroxyl group (). It is a highly reactive molecule that occurs both in the biosphere and in the inter ...


Examples of dialdehydes

*
Glyoxal Glyoxal is an organic compound with the chemical formula OCHCHO. It is the smallest dialdehyde (a compound with two aldehyde groups). It is a crystalline solid, white at low temperatures and yellow near the melting point (15 °C). The li ...
* Malondialdehyde *
Succindialdehyde Succinaldehyde or succindialdehyde is an organic compound with the formula (CH2CHO)2. Typical of other dialdehydes, succinaldehyde is highly reactive and is rarely observed as the dialdehyde. Usually, it is handled as the hydrates or methanol- ...
* Glutaraldehyde * Phthalaldehyde


Uses

Of all aldehydes, formaldehyde is produced on the largest scale, about . It is mainly used in the production of resins when combined with urea, melamine, and phenol (e.g., Bakelite). It is a precursor to methylene diphenyl diisocyanate ("MDI"), a precursor to polyurethanes.Reuss, G.; Disteldorf, W.; Gamer, A. O. and Hilt, A. (2005) "Formaldehyde" in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, Weinheim. . The second main aldehyde is
butyraldehyde Butyraldehyde, also known as butanal, is an organic compound with the formula CH3(CH2)2CHO. This compound is the aldehyde derivative of butane. It is a colorless flammable liquid with an unpleasant smell. It is miscible with most organic solvent ...
, of which about are prepared by
hydroformylation Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon ...
. It is the principal precursor to 2-ethylhexanol, which is used as a plasticizer.Kohlpaintner, C.; Schulte, M.; Falbe, J.; Lappe, P. and Weber, J. (2008) "Aldehydes, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, Weinheim. . Acetaldehyde once was a dominating product, but production levels have declined to less than because it mainly served as a precursor to acetic acid, which is now prepared by
carbonylation Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbon ...
of methanol. Many other aldehydes find commercial applications, often as precursors to alcohols, the so-called oxo alcohols, which are used in detergents. Some aldehydes are produced only on a small scale (less than 1000 tons per year) and are used as ingredients in flavours and
perfume Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent ...
s such as Chanel No. 5. These include
cinnamaldehyde Cinnamaldehyde is an organic compound with the formula(C9H8O) C6H5CH=CHCHO. Occurring naturally as predominantly the ''trans'' (''E'') isomer, it gives cinnamon its flavor and odor. It is a phenylpropanoid that is naturally synthesized by the shi ...
and its derivatives, citral, and lilial.


Nomenclature


IUPAC names for aldehydes

The common names for aldehydes do not strictly follow official guidelines, such as those recommended by
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
, but these rules are useful. IUPAC prescribes the following nomenclature for aldehydes: # Acyclic
aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated, like hexane ...
aldehydes are named as derivatives of the longest carbon chain containing the aldehyde group. Thus, HCHO is named as a derivative of methane, and CH3CH2CH2CHO is named as a derivative of butane. The name is formed by changing the suffix ''-e'' of the parent alkane to ''-al'', so that HCHO is named ''
methanal Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
'', and CH3CH2CH2CHO is named '' butanal''. # In other cases, such as when a -CHO group is attached to a ring, the suffix ''-carbaldehyde'' may be used. Thus, C6H11CHO is known as ''cyclohexanecarbaldehyde''. If the presence of another functional group demands the use of a suffix, the aldehyde group is named with the prefix ''formyl-''. This prefix is preferred to ''methanoyl-''. # If the compound is a natural product or a carboxylic acid, the prefix ''oxo-'' may be used to indicate which carbon atom is part of the aldehyde group; for example, CHOCH2COOH is named ''3-oxopropanoic acid''. # If replacing the aldehyde group with a carboxyl group (−COOH) would yield a carboxylic acid with a trivial name, the aldehyde may be named by replacing the suffix ''-ic acid'' or ''-oic acid'' in this trivial name by ''-aldehyde''.


Etymology

The word ''aldehyde'' was coined by Justus von Liebig as a contraction of the Latin (dehydrogenated alcohol).. In the past, aldehydes were sometimes named after the corresponding alcohols, for example, ''vinous aldehyde'' for acetaldehyde. (''Vinous'' is from
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
"wine", the traditional source of
ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
, cognate with '' vinyl''.) The term ''formyl group'' is derived from the
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
word "ant". This word can be recognized in the simplest aldehyde,
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
, and in the simplest carboxylic acid, formic acid.


See also

*
Enol In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene ( olefin) with a hydroxyl group attached to one end of the alkene double bond (). T ...
*
Pseudoacid A pseudoacid in organic chemistry is a cyclic oxocarboxylic acid. Most commonly, these form from aldehyde and keto carboxylic acids, and the cyclic forms are furanoid (5-ring with oxygen) or pyranoid (6-ring with oxygen). The original pseudoa ...


References


External links

{{Authority control Functional groups 1830s neologisms