An aldehyde.
-R is the group attached to the aldehyde group.

An aldehyde is an organic compound containing a terminal carbonyl group. This functional group, which consists of a carbon atom which is bonded to a hydrogen atom and double-bonded to an oxygen atom (chemical formula O=CH-), is called the aldehyde group. The aldehyde group is also called the formyl or methanoyl group. Image File history File links Download high resolution version (787x742, 9 KB) Summary Description: Structural formula of a general aldehyde group (RCHO). ... Image File history File links Download high resolution version (787x742, 9 KB) Summary Description: Structural formula of a general aldehyde group (RCHO). ... In chemistry, a carbonyl group is a functional group composed of an atom of carbon double-bonded to an atom of oxygen. ... In organic chemistry, functional groups are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...

The word aldehyde seems to have arisen from alcohol dehydrogenated. In the past, aldehydes were sometimes named after the corresponding alcohols, for example vinous aldehyde for acetaldehyde. (Vinous is from Latin vinum = wine, the traditional source of ethanol; compare vinyl.) Functional group of an alcohol molecule. ... R-phrases , , S-phrases , , , Flash point −39 °C Autoignition temperature 185 °C RTECS number AB1925000 Supplementary data page Structure and properties n, εr, etc. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Grain alcohol redirects here. ... Chemical structure of the vinyl functional group. ...

The aldehyde group is polar. Oxygen, more electronegative than carbon, pulls the electrons in the carbon-oxygen bond towards itself, creating an electron deficiency at the carbon atom. A commonly-used example of a polar compound is water (H2O). ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... It has been suggested that this article or section be merged with electronegativity. ... A carbon-oxygen bond is a covalent bond between carbon and oxygen and one of the most abundant in organic chemistry and biochemistry [1]. Oxygen has 6 valence electrons and prefers to share two electrons in bonding with carbon, leaving the remaining 4 nonbonding in 2 lone pairs. ...

Owing to resonance stabilization of the conjugate base, an α-hydrogen in an aldehyde is more acidic than a hydrogen atom in an alkane, with a typical pKa of 17. The alpha carbon in organic chemistry refers to the first carbon after the carbon that attaches to the functional group (the carbon is attached at the first, or alpha, position). ... In chemistry and biochemistry, acid dissociation constant, the acidity constant, or the acid-ionization constant () is a specific type of equilibrium constant that indicates the extent of dissociation of hydrogen ions from an acid. ...

Nomenclature

IUPAC names for aldehydes

IUPAC prescribes the following nomenclature for aldehydes: The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ...

1. Acyclic aliphatic 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, and CH₃CH₂CH₂CHO is named butanal.
2. 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.
3. If another functional group is present which IUPAC rules prescribe must be named as a suffix, the aldehyde group is named with the prefix formyl-. This prefix is preferred to methanoyl-.
4. If replacing the aldehyde group with a carboxyl (-COOH) group 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. For example:

• HCHO may be called formaldehyde.
• CH₃CHO may be called acetaldehyde.
• C₆H₅CHO may be called benzaldehyde.

In chemistry, aliphatic compounds are organic compounds in which carbon atoms are joined together in straight or branched chains. ... Chemical structure of methane, the simplest alkane Alkanes are chemical compounds that consist only of the elements carbon (C) and hydrogen (H) (i. ... The chemical compound formaldehyde (also known by IUPAC nomenclature as methanal), is a gas with a strong pungent smell. ... Butanal (C4H8O; alternate names include butyraldehyde, butyl aldehyde, butal, and butanaldehyde) is the aldehyde analog of butane. ... The chemical compound formaldehyde (also known as methanal) is a gas with a pungent smell. ... R-phrases , , S-phrases , , , Flash point −39 °C Autoignition temperature 185 °C RTECS number AB1925000 Supplementary data page Structure and properties n, εr, etc. ... Benzaldehyde (C6H5CHO) is a chemical compound consisting of a benzene ring with an aldehyde substituent. ...

Other nomenclature

The carbon atom adjacent to a carbonyl group is called the α carbon. Carbon atoms further away from the group may be named β for the carbon atom bonded to the α carbon, γ for the next, and so on. Hydrogen atoms bonded to these carbon atoms are named likewise: an α hydrogen is a hydrogen atom bonded to the α carbon and so on.

A reaction that introduces an aldehyde group is known as a formylation reaction. A Formylation reaction in organic chemistry is the catch-all name for any organic reaction in which an organic compound is functionalized with a formyl group -CH=0. ...

Chemistry

Synthesis

There are several methods for preparing aldehydes:

• Reacting a primary alcohol with an oxidizing agent. In the laboratory this may be achieved by heating the alcohol with a chromium(VI) reagent an acidified solution of potassium dichromate, which is reduced to green Cr³⁺ during the reaction. Excess dichromate will further oxidise the aldehyde to form a carboxylic acid, so either the aldehyde is distilled out as it forms (if volatile), or milder methods and reagents such as PCC oxidation, IBX acid, Dess-Martin periodinane or Swern oxidation are used. The reaction is illustrated below with propan-1-ol being oxidised to form propionaldehyde, and again with pentan-1-ol being oxidized to form pentanal.

CH₃CH₂CH₂OH — → CH₃CH₂CHO

• Reacting an alkene (if there is a vinylic hydrogen) with ozone will form an ozonide (an unstable, explosive intermediate) which yields an aldehyde upon reduction with zinc and acid at reduced temperatures. This process is called ozonolysis.
• Reacting an ester with diisobutyl aluminium hydride (DIBAL-H) or sodium aluminium hydride can cause reduction, yielding an aldehyde.
• Reduction of an acid chloride using the Rosenmund reduction or using lithium tri-t-butoxyaluminium hydride (LiAlH(O-t-C₄H₉)₃).
• Reaction of ketones with methoxymethylenetriphenylphosphine in a modified Wittig reaction.
• Various formylation reactions, such as the Vilsmeier-Haack reaction, can be used to introduce an aldehyde group.
• In the Nef reaction, aldehydes form by hydrolysis of salts of primary nitro compounds.
• Zincke aldehydes form by reaction of pyridinium salts with secondary amines followed by hydrolysis.
• in the Stephen aldehyde synthesis aldehydes form from nitriles, tin chloride and hydrochloric acid.

Functional group of an alcohol molecule. ... European Union Chemical hazard symbol for oxidizing agents Dangerous goods label for oxidising agents An oxidizing agent (also called an oxidant or oxidizer) is referred to as A chemical compound that readily transfers oxygen atoms or A substance that gains electrons in a redox chemical reaction. ... Potassium dichromate, K2Cr2O7 is used in oxidation reactions. ... Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... Chromates and Dichromates are salts of chromic acid. ... Structure of a carboxylic acid The 3D structure of the carboxyl group A space-filling model of the carboxyl group Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H. [1] Carboxylic acids are Bronsted... Laboratory distillation set-up using, without a fractionating column 1: Heat source 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed... In chemistry and physics, Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... Pyridinium chlorochromate, a reddish orange solid reagent, is used to oxidize primary alcohols to aldehydes and secondary alcohols to ketones. ... IBX acid IBX acid or 2-Iodoxybenzoic acid is an organic compound used in organic chemistry as an oxidizing agent. ... The Dess-Martin periodinane is a chemical reagent used to oxidize alcohols to aldehydes and ketones. ... The mild oxidation of primary or secondary alcohols to aldehydes or ketones with a mixture of oxalyl chloride, dimethylsulfoxide and triethylamine is called the Swern oxidation. ... R-phrases , , S-phrases , , , , , Flash point 15 °C RTECS number UH8225000 Supplementary data page Structure and properties n, εr, etc. ... Image File history File links This is a lossless scalable vector image. ... The chemical structure of ethylene, the simplest alkene. ... Chemical structure of the vinyl functional group. ... It has been suggested that Ozone generator be merged into this article or section. ... In ozonolysis ozone cleaves an alkene into carbonyl compounds. ... A carboxylic acid ester. ... DIBAH (Diisobutylaluminum hydride) is a reducing agent, useful in reducing esters to aldehydes. ... In organic chemistry, an acid chloride (or acyl chloride) is very reactive derivative of a carboxylic acid. ... The Rosenmund reduction is a chemical reaction that reduces an acid halide to an aldehyde using hydrogen gas over palladium-on-carbon poisoned with barium sulfate. ... Methoxymethylenetriphenylphosphine is a Wittig reagent with used as an reagent in the homologization of aldehydes and ketones to extended aldehydes, an organic reaction first reported in 1958 . ... The Wittig reaction is a chemical reaction of an aldehyde or ketone with a phosphonium ylide to give an alkene and triphenylphosphine oxide. ... A Formylation reaction in organic chemistry is the catch-all name for any organic reaction in which an organic compound is functionalized with a formyl group -CH=0. ... The Vilsmeier-Haack reaction or Vilsmeier reaction is an organic reaction between a substituted amide and a activated arene in the presence of phosphorus oxychloride. ... The Nef reaction is an organic reaction describing the acid hydrolysis of a salt of a primary or secondary nitroalkane to an aldehyde or a ketone and nitrous oxide [1]. The reaction was reported by the chemist J.U. Nef in 1894 [2]who treated the sodium salt of nitroethane... The Zincke reaction is an organic reaction in which a pyridine is transformed into a pyridinium salt by reaction with 2,4-dinitro-chlorobenzene and a primary amine. ... Stephen aldehyde synthesis, a named reaction in chemistry, invented by Henry Stephen (OBE/MBE). ...

Keto-enol tautomerism

Aldehydes can exist in either the keto or enol tautomers. Keto-enol tautomerism is catalyzed by either acid or base. Enol (or, more officially, but less commonly: alkenol) is an alkene with hydroxyl group on one of the carbon atoms of the double bond. ... In organic chemistry, a keto-enol tautomerism is an equilibrium between a ketone or aldehyde (the keto form) and an enol. ... In organic chemistry, keto-enol tautomerism refers to a chemical equilibrium between a keto form (a ketone or an aldehyde) 1 and an enol 2. ...

Common reactions

Reduction and oxidation

• The aldehyde group can be reduced to the group -CH₂OH, changing the Utkarsh into a primary alcohol.
• The aldehyde group can be oxidized to the group -COOH, yielding a carboxylic acid. Suitable oxidizing agents include potassium permanganate, nitric acid, chromium(VI) oxide, and acidified potassium dichromate.
  • Another oxidation reaction is 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 solution to redissolve the precipitate in aqueous ammonia to produce [Ag(NH₃)₂]⁺ complex. This reagent will convert aldehydes to carboxylic acids without attacking carbon-carbon double-bonds. The name silver mirror test arises because this reaction will produce a precipitate of silver whose presence can be used to test for the presence of an aldehyde.

In general usage, alcohol (from Arabic al-khwl الكحول, or al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). ... Structure of a carboxylic acid The 3D structure of the carboxyl group A space-filling model of the carboxyl group Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H. [1] Carboxylic acids are Bronsted... Potassium permanganate is the chemical compound KMnO4. ... The chemical compound nitric acid (HNO3), also known as aqua fortis and spirit of nitre, is an aqueous solution of hydrogen nitrate (anhydrous nitric acid). ... In chemistry, chromic acid is a chromium (Cr) compound, yet to be isolated, with the formula H2CrO4. ... For alternative meanings see acid (disambiguation). ... Potassium dichromate, K2Cr2O7 is used in oxidation reactions. ... Tollens reagent is usually ammoniacal silver nitrate, but can also be other things, as long as there is an aqueous diamminesilver(I) complex. ... Sodium hydroxide (NaOH), also known as lye or caustic soda or sodium hydrate, is a caustic metallic base. ... R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Ammonia is a compound with the formula NH3. ...

Nucleophilic addition reactions

In nucleophilic addition reactions a nucleophile can add to the carbon atom in the carbonyl group, yielding an addition compound where this carbon atom has tetrahedral molecular geometry. Together with protonation of the oxygen atom in the carbonyl group (which can take place either before or after addition), this yields a product where the carbon atom in the carbonyl group is bonded to the nucleophile, a hydrogen atom, and a hydroxyl group. In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ... In a tetrahedral molecular geometry a central atom is located at the center with four substituents located at the corners of a tetrahedron. ...

In many cases, a water molecule is removed after the addition takes place; in this case, the reaction is classed as an addition-elimination or addition-condensation reaction. An addition reaction, in chemistry, is in its simplest terms an organic reaction where two or more molecules combine to form a larger one. ... An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one or two-step mechanism. ... An addition reaction, in chemistry, is in its simplest terms an organic reaction where two or more molecules combine to form a larger one. ... A 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. ...

There are various examples of nucleophilic addition reactions.

• 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 can be stable. Acetals are stable, but revert to the aldehyde in the presence of acid.
• Aldehydes can react with water (under acidic or basic conditions) to form hydrates, R-C(H)(OH)(OH), although these are only stable when strong electron withdrawing groups are present, as in chloral hydrate. The mechanism is identical to hemiacetal formation.
• 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 the case of a primary amine, a water molecule can be eliminated from the carbinolamine to yield an imine. This reaction is catalyzed by acid.
• The cyano group in HCN can add to the carbonyl group to form cyanohydrins, R-C(H)(OH)(CN).
• In the Grignard reaction, a Grignard reagent adds to the group, eventually yielding an alcohol with a substituted group from the Grignard reagent.
• Hydroxylamine (NH₂OH) can add to the carbonyl group. After the elimination of water, this will result in an oxime.
• An ammonia derivative of the form H₂NNR₂ such as hydrazine (H₂NNH₂) or 2,4-dinitrophenylhydrazine can add to the carbonyl group. After the elimination of water, this will result in the formation of a hydrazone.

Acetalisation is an organic reaction that involves is the formation of an acetal or ketal. ... Acidity redirects here. ... Acids and bases: Acid-base reaction pH Self-ionization of water Buffer solutions Systematic naming Acid-base extraction Acidity function Proton affinity Acids: Strong acids Weak acids Superacids Lewis acids Mineral acids Organic acids Bases: Strong bases Weak bases Superbases Lewis bases Organic bases edit In chemistry, a base is... Functional group of an alcohol molecule. ... A hemiacetal is a functional group or compound containing the function group in the form of: where R and R are any carbon backbones. ... Acidity redirects here. ... An acetal is a functional group or molecule containing the functional group of a carbon bonded to two -OR groups. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Hydrate is a term which means different things in inorganic chemistry and organic chemistry. ... The Polar effect or electronic effect in chemistry is the effect exerted by a substituent on modifying electrostatic forces operating on a nearby reaction center. ... Chloral hydrate, also known as trichloroacetaldehyde monohydrate, 2,2,2-trichloro-1,1-ethanediol, and under the tradenames Aquachloral, Novo-Chlorhydrate, Somnos, Noctec, and Somnote, is a sedative and hypnotic drug as well as a chemical reagent and precursor. ... Alkylimino-de-oxo-bisubstitution in organic chemistry is the organic reaction of carbonyl compounds with amines to imines . ... The general structure of an imine An imine is a functional group or chemical compound containing a carbon-nitrogen double bond. ... Hydrogen cyanide is a chemical compound with chemical formula HCN. A solution of hydrogen cyanide in water is called hydrocyanic acid. ... Cyanohydrin is any of several compounds that contain both the CN and OH radicals. ... The Grignard reaction is an organometallic chemical reaction involving alkyl- or aryl-magnesium halides, also called Grignard reagents, with electrophiles. ... A Grignard Reagent is an alkyl- or aryl- magnesium halide. ... Hydroxylamine is a reactive chemical with formula NH2OH. It can be considered a hybrid of ammonia and water due to parallels it shares with each. ... An oxime is one in a class of chemical compounds with the general formula R1R2 C N O H, where R1 is an organic side chain and R2 is either hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. ... Ammonia is a compound with the formula NH3. ... Hydrazine is the chemical compound with formula N2H4. ... Chemical structure of 2,4-Dinitrophenylhydrazine 2,4-Dinitrophenylhydrazine (or Bradys reagent) is a chemical compound that can be used in a chemical test to detect whether an organic compound has a ketone or aldehyde functional group. ... Benzophenone hydrazone, an example hydrazone In chemistry, a hydrazone is a compound with the structure R2C=NNR2, differing from a ketone or aldehyde by the replacement of the double bonded oxygen with the =NNR2 functional group. ...

More complex reactions

• If an aldehyde is converted to a simple hydrazone (RCH=NHNH₂) and this is heated with a base such as KOH, the terminal carbon is fully reduced via the Wolff-Kishner reaction to a methyl group. The Wolff-Kishner reaction may be performed as a one-pot reaction, giving the overall conversion RCH=O → RCH₃.
• Reaction of aldehydes with reducing agents such as magnesium gives diols in a Pinacol coupling reaction.
• The Wittig reaction takes aldehydes to alkenes and the Corey-Fuchs reaction takes aldehydes to alkynes. Both use a triphenylphosphine reagent. The Corey-Chaykovsky reagent is a sulfonium ylide which converts aldehydes to epoxides.

The chemical compound potassium hydroxide, (KOH) sometimes known as caustic potash, potassa, potash lye, and potassium hydrate, is a metallic base. ... The Wolff-Kishner reduction fully reduces aldehydes and ketones to an alkane. ... In chemistry a methyl-group is a hydrophobic Alkyl functional group which is derived from methane (CH4). ... In chemistry a one-pot synthesis is a strategy with the aim to improve the effiency of a chemical reaction whereby a reactant is subjected to successive chemical reactions in one and the same reactor. ... A reducing agent (also called a reductant or reducer) is the element or a compound in a redox (reduction-oxidation) reaction (see electrochemistry) that reduces another species. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... A diol is a chemical compound containing two hydroxyl groups (-OH groups). ... The Pinacol coupling reaction A pinacol coupling reaction is an organic reaction in which a carbon carbon covalent bond is formed between the carbonyl groups of an aldehyde or a ketone in presence of an electron donor in a free radical process . ... The Wittig reaction is a chemical reaction of an aldehyde or ketone with a phosphonium ylide to give an alkene and triphenylphosphine oxide. ... The chemical structure of ethylene, the simplest alkene. ... The Corey-Fuchs reaction is a series of chemical reactions designed to transform an aldehyde into an alkyne. ... The structural formula of 2-butyne, a simple alkyne-containing molecule Alkynes are hydrocarbons that have at least one triple bond between two carbon atoms, with the formula CnH2n-2. ... Triphenylphosphine (in Europe: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. ... The Johnson-Corey-Chaykovsky reaction is a chemical reaction in which a carbonyl is converted to an epoxide by the action of a sulfonium ylide. ... An ylide is a neutral molecule with positive and negative charges on adjacent atoms. ... An epoxide is a cyclic ether with only three ring atoms. ...

Examples of aldehydes

• Methanal (Formaldehyde)
• Ethanal (Acetaldehyde)
• Propionaldehyde (propanal)
• Butyraldehyde (butanal)
• Glucose
• Benzaldehyde
• Cinnamaldehyde

The chemical compound formaldehyde (also known by IUPAC nomenclature as methanal), is a gas with a strong pungent smell. ... The chemical compound formaldehyde (also known as methanal) is a gas with a pungent smell. ... Acetaldehyde, also known as ethanal, is a chemical compound, an aldehyde with formula CH3CHO and structure It is a highly reactive flammable liquid with a strong fruity smell. ... R-phrases , , S-phrases , , , Flash point −39 °C Autoignition temperature 185 °C RTECS number AB1925000 Supplementary data page Structure and properties n, εr, etc. ... R-phrases , S-phrases , , Flash point −26°C Autoignition temperature 175°C RTECS number  ? Supplementary data page Structure and properties n, εr, etc. ... Butanal (C4H8O; alternate names include butyraldehyde, butyl aldehyde, butal, and butanaldehyde) is the aldehyde analog of butane. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Benzaldehyde (C6H5CHO) is a chemical compound consisting of a benzene ring with an aldehyde substituent. ... Cinnamic aldehyde or cinnamaldehyde (more precisely trans-cinnamaldehyde, the only naturally-occurring form) is the chemical compound that gives cinnamon its spice. ...

Related compounds

Other kinds of organic compounds containing carbonyl groups include In chemistry, a carbonyl group is a functional group composed of an atom of carbon double-bonded to an atom of oxygen. ...

• Ketones
• Carboxylic acids

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