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{{short description|1=Organic compounds of the form >C=O}}
[[File:Ketone-group-2D-skeletal.svg|150px|right|thumb|Ketone]]
{{Multiple image|direction=vertical|align=right|image1=Aceton.svg|image2=Acetone-3D-balls.png|width=150|caption2=[[Chemistry:Acetone|Acetone]]}}

In [[Chemistry:Organic chemistry|organic chemistry]], a '''ketone''' {{IPAc-en|ˈ|k|iː|t|oʊ|n}} is an [[Chemistry:Organic compound|organic compound]] with the structure {{chem2|R\sC(\dO)\sR'}}, where R and R' can be a variety of [[Chemistry:Carbon|carbon]]-containing [[Chemistry:Substituent|substituent]]s. Ketones contain a [[Chemistry:Carbonyl group|carbonyl group]] {{chem2|\sC(\dO)\s}} (which contains a carbon-oxygen [[Chemistry:Double bond|double bond]] C=O). The simplest ketone is [[Chemistry:Acetone|acetone]] (where R and R' is methyl), with the formula {{chem2|(CH3)2CO}}. Many ketones are of great importance in biology and in industry. Examples include many [[Chemistry:Sugar|sugar]]s ([[Chemistry:Ketose|ketose]]s), many steroids (e.g., [[Chemistry:Testosterone|testosterone]]), and the [[Physics:Solvent|solvent]] [[Chemistry:Acetone|acetone]].<ref name="raymond2010">{{
cite book |last=Raymond |first=Kenneth W. |title=General Organic and Biological Chemistry |edition=3rd |publisher=Wiley |year=2010 |page=297}}</ref>

==Nomenclature and etymology==
The word ''ketone'' is derived from ''Aketon'', an old German word for ''acetone''.<ref>{{OEtymD|ketone}}</ref><ref>The word "ketone" was coined in 1848 by the German chemist Leopold Gmelin. See: Leopold Gmelin, ed., ''Handbuch der organischen Chemie: Organische Chemie im Allgemeinen'' … (Handbook of organic chemistry: Organic chemistry in general … ), 4th ed., (Heidelberg, (Germany): Karl Winter, 1848), volume 1, p. 40. From page 40: ''"Zu diesen Syndesmiden scheinen auch diejenigen Verbindungen zu gehören, die als ''Acetone im Allegemeinen'' (''Ketone?'') bezeichnet werden."'' (To these syndesmides*, those compounds also seem to belong, which are designated as ''acetones in general'' (''ketones?'').") [*Note: In 1844, the French chemist Auguste Laurent suggested a new nomenclature for organic compounds. One of his new classes of compounds was "syndesmides", which were compounds formed by the combination of two or more simpler organic molecules (from the Greek σύνδεσμος (''syndesmos'', union) + ''-ide'' (indicating a group of related compounds)). For example, acetone could be formed by the dry distillation of metal acetates, so acetone was the syndesmide of two acetate ions. See: Laurent, Auguste (1844) [https://books.google.com/books?id=2wVQAAAAYAAJ&pg=PA1089 "Classification chimique,"] ''Comptes rendus'', '''19''' : 1089–1100 ; see especially p. 1097.</ref>

According to the rules of IUPAC nomenclature, ketone names are derived by changing the [[Social:Suffix|suffix]] ''-ane'' of the parent [[Chemistry:Alkane|alkane]] to ''-anone''. Typically, the position of the carbonyl group is denoted by a number, but traditional nonsystematic names are still generally used for the most important ketones, for example [[Chemistry:Acetone|acetone]] and [[Chemistry:Benzophenone|benzophenone]]. These nonsystematic names are considered retained IUPAC names,<ref>List of retained IUPAC names [http://www.acdlabs.com/iupac/nomenclature/93/r93_701.htm retained IUPAC names Link]</ref> although some introductory chemistry textbooks use systematic names such as "2-propanone" or "propan-2-one" for the simplest ketone ({{chem2|[[Chemistry:Carbon|C]][[Chemistry:Hydrogen|H]]3\sC(\d[[Chemistry:Oxygen|O]])\sCH3}}) instead of "acetone".

The derived names of ketones are obtained by writing separately the names of the two [[Chemistry:Alkyl group|alkyl group]]s attached to the carbonyl group, followed by "ketone" as a separate word. Traditionally the names of the alkyl groups were written in order of increasing complexity, for example [[Chemistry:Butanone|methyl ethyl ketone]]. However, according to the rules of IUPAC nomenclature, the alkyl groups are written alphabetically, for example [[Chemistry:Butanone|ethyl methyl ketone]]. When the two alkyl groups are the same, the prefix "di-" is added before the name of alkyl group. The positions of other groups are indicated by Greek letters, the α-carbon being the atom adjacent to carbonyl group.

Although used infrequently, ''oxo'' is the IUPAC nomenclature for the oxo group (=O) and used as prefix when the ketone does not have the highest priority. Other prefixes, however, are also used. For some common chemicals (mainly in biochemistry), ''keto'' refer to the ketone [[Chemistry:Functional group|functional group]].

==Structure and properties==
[[File:KetoneVarietyPack.png|thumb|600px|center|Representative ketones, from the left: acetone, a common solvent; oxaloacetate, an intermediate in the metabolism of sugars; acetylacetone in its (mono) enol form (the enol highlighted in blue); cyclohexanone, precursor to nylon; muscone, an animal scent; and tetracycline, an antibiotic.]]

The ketone carbon is often described as [[Physics:Orbital hybridisation#sp2|sp<sup>2</sup> hybridized]], a description that includes both their electronic and molecular structure. Ketones are trigonal planar around the ketonic carbon, with C–C–O and C–C–C bond angles of approximately 120°. Ketones differ from [[Chemistry:Aldehyde|aldehyde]]s in that the carbonyl group (C=O) is bonded to two carbons within a carbon skeleton. In aldehydes, the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains. Ketones are also distinct from other carbonyl-containing [[Chemistry:Functional group|functional group]]s, such as [[Chemistry:Carboxylic acid|carboxylic acid]]s, [[Chemistry:Ester|ester]]s and [[Chemistry:Amide|amide]]s.<ref>{{McMurry3rd}}</ref>

The carbonyl group is polar because the electronegativity of the oxygen is greater than that for carbon. Thus, ketones are nucleophilic at oxygen and electrophilic at carbon. Because the carbonyl group interacts with water by [[Chemistry:Hydrogen bond|hydrogen bond]]ing, ketones are typically more soluble in water than the related methylene compounds. Ketones are hydrogen-bond acceptors. Ketones are not usually hydrogen-bond donors and cannot hydrogen-bond to themselves. Because of their inability to serve both as hydrogen-bond donors and acceptors, ketones tend not to "self-associate" and are more volatile than alcohols and [[Chemistry:Carboxylic acid|carboxylic acid]]s of comparable [[Physics:Molecular weight|molecular weight]]s. These factors relate to the pervasiveness of ketones in perfumery and as solvents.

===Classes of ketones===
Ketones are classified on the basis of their substituents. One broad classification subdivides ketones into symmetrical and unsymmetrical derivatives, depending on the equivalency of the two organic substituents attached to the carbonyl center. Acetone and [[Chemistry:Benzophenone|benzophenone]] ({{chem2|(C6H5)2CO}}) are symmetrical ketones. [[Chemistry:Acetophenone|Acetophenone]] {{chem2|(C6H5C(O)CH3)}} is an unsymmetrical ketone.

====Diketones====
{{main|Chemistry:Dicarbonyl}}
Many kinds of diketones are known, some with unusual properties. The simplest is [[Chemistry:Diacetyl|diacetyl]] {{chem2|(CH3C(O)C(O)CH3)}}, once used as butter-flavoring in popcorn. [[Chemistry:Acetylacetone|Acetylacetone]] (pentane-2,4-dione) is virtually a misnomer (inappropriate name) because this species exists mainly as the monoenol {{chem2|CH3C(O)CH\dC(OH)CH3}}. Its enolate is a common ligand in coordination chemistry.

====Unsaturated ketones====
Ketones containing [[Chemistry:Alkene|alkene]] and [[Chemistry:Alkyne|alkyne]] units are often called unsaturated ketones. The most widely used member of this class of compounds is [[Chemistry:Methyl vinyl ketone|methyl vinyl ketone]], {{chem2|CH3C(O)CH\dCH2}}, which is useful in the [[Chemistry:Robinson annulation|Robinson annulation]] reaction. Lest there be confusion, a ketone itself is a site of unsaturation; that is, it can be hydrogenated.

====Cyclic ketones====
Many ketones are cyclic. The simplest class have the formula {{chem2|(CH2)_{''n''}CO}}, where ''n'' varies from 2 for [[Chemistry:Cyclopropanone|cyclopropanone]] ({{chem2|(CH2)2CO}}) to the tens. Larger derivatives exist. [[Chemistry:Cyclohexanone|Cyclohexanone]] ({{chem2|(CH2)5CO}}), a symmetrical cyclic ketone, is an important intermediate in the production of [[Chemistry:Nylon|nylon]]. [[Chemistry:Isophorone|Isophorone]], derived from acetone, is an unsaturated, asymmetrical ketone that is the precursor to other [[Chemistry:Polymer|polymer]]s. [[Chemistry:Muscone|Muscone]], 3-methylpentadecanone, is an animal [[Biology:Pheromone|pheromone]]. Another cyclic ketone is [[Chemistry:Cyclobutanone|cyclobutanone]], having the formula {{chem2|(CH2)3CO}}.

===Keto-enol tautomerization===
{{main|Biology:Enol}}
[[Image:Keto enol tautomerism.svg|thumb|right|250px|Keto-enol tautomerism. '''1''' is the keto form; '''2''' is the enol.]]
Ketones that have at least one alpha-hydrogen, undergo keto-enol tautomerization; the tautomer is an [[Biology:Enol|enol]]. Tautomerization is catalyzed by both acids and bases. Usually, the keto form is more stable than the enol. This equilibrium allows ketones to be prepared via the [[Chemistry:Hydration reaction|hydration]] of [[Chemistry:Alkyne|alkyne]]s.

===Acid/base properties of ketones===
{{chem2|C\sH}} bonds adjacent to the carbonyl in ketones are more acidic [[Chemistry:Acid dissociation constant|p''K''<sub>a</sub>]]&nbsp;≈&nbsp;20) than the {{chem2|C\sH}} bonds in alkane (p''K''<sub>a</sub>&nbsp;≈&nbsp;50). This difference reflects resonance stabilization of the enolate ion that is formed upon [[Chemistry:Deprotonation|deprotonation]]. The relative acidity of the α-hydrogen is important in the enolization reactions of ketones and other carbonyl compounds. The acidity of the α-hydrogen also allows ketones and other carbonyl compounds to react as nucleophiles at that position, with either stoichiometric and catalytic base. Using very strong bases like lithium diisopropylamide (LDA, p''K''<sub>a</sub> of conjugate acid ~36) under non-equilibrating conditions (–78&nbsp;°C, 1.1 equiv LDA in THF, ketone added to base), the less-substituted ''kinetic'' ''enolate'' is generated selectively, while conditions that allow for equilibration (higher temperature, base added to ketone, using weak or insoluble bases, e.g., [[Chemistry:Sodium ethoxide|{{chem2|CH3CH2ONa}}]] in [[Chemistry:Ethanol|{{chem2|CH3CH2OH}}]], or [[Chemistry:Sodium hydride|NaH]]) provides the more-substituted ''thermodynamic enolate''.

Ketones are also weak bases, undergoing [[Chemistry:Protonation|protonation]] on the carbonyl oxygen in the presence of Brønsted acids. Ketonium ions (i.e., protonated ketones) are strong acids, with p''K''<sub>a</sub> values estimated to be somewhere between –5 and –7.<ref>{{Cite web|url=http://evans.rc.fas.harvard.edu/pdf/evans_pKa_table.pdf|title=Evans pKa table|last=Evans|first=David A.|date=4 November 2005|website=Evans group website|access-date=14 June 2018|archive-date=19 June 2018|archive-url=https://web.archive.org/web/20180619071445/http://evans.rc.fas.harvard.edu/pdf/evans_pKa_table.pdf|url-status=dead}}</ref><ref>{{Cite book|title=March's Advanced Organic Chemistry|last=Smith|first=Michael B.|publisher=Wiley|year=2013|isbn=978-0-470-46259-1|edition=7th|location=Hoboken, N.J.|pages=314–315}}</ref> Although acids encountered in organic chemistry are seldom strong enough to fully protonate ketones, the formation of equilibrium concentrations of protonated ketones is nevertheless an important step in the mechanisms of many common organic reactions, like the formation of an acetal, for example. Acids as weak as pyridinium cation (as found in pyridinium tosylate) with a p''K''<sub>a</sub> of 5.2 are able to serve as catalysts in this context, despite the highly unfavorable equilibrium constant for protonation (''K''<sub>eq</sub>&nbsp;<&nbsp;10<sup>−10</sup>).

==Characterization==
An aldehyde differs from a ketone in that it has a hydrogen atom attached to its carbonyl group, making aldehydes easier to oxidize. Ketones do not have a hydrogen atom bonded to the carbonyl group, and are therefore more resistant to oxidation. They are oxidized only by powerful oxidizing agents which have the ability to [[Chemistry:Bond cleavage|cleave]] carbon–carbon bonds.

===Spectroscopy===
Ketones and aldehydes absorb strongly in the [[Physics:Infrared spectroscopy|infra-red spectrum]] near 1700 [[Physics:Wavenumber|cm<sup>−1</sup>]]. The exact position of the peak depends on the substituents.

Whereas <sup>1</sup>H NMR [[Physics:Spectroscopy|spectroscopy]] is generally not useful for establishing the presence of a ketone, <sup>13</sup>C NMR spectra exhibit signals somewhat downfield of 200 [[Physics:Parts-per notation#ppm|ppm]] depending on structure. Such signals are typically weak due to the absence of [[Physics:Nuclear Overhauser effect|nuclear Overhauser effect]]s. Since aldehydes resonate at similar [[Physics:Chemical shift|chemical shift]]s, multiple resonance experiments are employed to definitively distinguish aldehydes and ketones.

===Qualitative organic tests===
Ketones give positive results in Brady's test, the reaction with 2,4-dinitrophenylhydrazine to give the corresponding hydrazone. Ketones may be distinguished from aldehydes by giving a negative result with [[Chemistry:Tollens' reagent|Tollens' reagent]] or with [[Chemistry:Fehling's solution|Fehling's solution]]. Methyl ketones give positive results for the iodoform test.<ref>{{VogelQuantitative6th}}</ref> Ketones also give positive results when treated with ''m''-dinitrobenzene in presence of dilute sodium hydroxide to give violet coloration.

==Synthesis==<!-- This section is linked from [[Chemistry:Organic reaction|Organic reaction]] -->
Many methods exist for the preparation of ketones in industrial scale and academic laboratories. Ketones are also produced in various ways by organisms; see the section on biochemistry below.

In industry, the most important method probably involves oxidation of hydrocarbons, often with air. For example, a billion kilograms of [[Chemistry:Cyclohexanone|cyclohexanone]] are produced annually by aerobic oxidation of [[Chemistry:Cyclohexane|cyclohexane]]. Acetone is prepared by [[Chemistry:Cumene process|air-oxidation of cumene]].

For specialized or small scale [[Chemistry:Organic synthesis|organic synthetic]] applications, ketones are often prepared by [[Chemistry:Alcohol oxidation#Oxidation to ketones|oxidation of secondary alcohols]]:
:{{chem2|R2CH(OH) + "O" → R2C\dO + H2O}}
Typical strong oxidants (source of "O" in the above reaction) include [[Chemistry:Potassium permanganate|potassium permanganate]] or a [[Chemistry:Chromium|Cr(VI)]] compound. Milder conditions make use of the [[Chemistry:Dess–Martin periodinane|Dess–Martin periodinane]] or the [[Chemistry:Swern oxidation|Moffatt–Swern]] methods.

Many other methods have been developed, examples include:<ref name=March>{{March6th}}</ref>
* By [[Chemistry:Geminal halide hydrolysis|geminal halide hydrolysis]].<ref>{{cite journal|last1=Marvel|first1=C. S.|last2=Sperry|first2=W. M.|title=Benzophenone|journal=Organic Syntheses|date=1928|volume=8|page=26|doi=10.15227/orgsyn.008.0026}}</ref>
* By [[Chemistry:Hydration reaction|hydration]] of [[Chemistry:Alkyne|alkyne]]s.<ref name=Vogel>{{cite book|author1=Furniss, Brian |author2=Hannaford, Antony |author3=Smith, Peter |author4=Tatchell, Austin |title=Vogel's Textbook of Practical Organic Chemistry|year=1996|publisher=Longman Science & Technical|location=London|edition=5th|isbn=9780582462366|pages=612–623, 976–977, 982–983|url=https://archive.org/details/TextbookOfPracticalOrganicChemistry5thEd}}</ref> Such processes occur via [[Biology:Enol|enol]]s and require the presence of an acid and [[Chemistry:Mercury(II) sulfate|mercury(II) sulfate]] ({{chem2|HgSO4}}). Subsequent enol–keto tautomerization gives a ketone. This reaction always produces a ketone, even with a terminal alkyne, the only exception being the hydration of [[Chemistry:Acetylene|acetylene]], which produces [[Chemistry:Acetaldehyde|acetaldehyde]].
*From [[Chemistry:Weinreb ketone synthesis|Weinreb Amides]] using stoichiometric organometallic reagents.
* Aromatic ketones can be prepared in the Friedel–Crafts acylation,<ref name="Friedel">{{cite journal|last1=Allen|first1=C. F. H.|last2=Barker|first2=W. E.|title=Desoxybenzoin|journal=Organic Syntheses|date=1932|volume=12|page=16|doi=10.15227/orgsyn.012.0016}}</ref> the related Houben–Hoesch reaction,<ref>{{cite journal|last1=Gulati|first1=K. C.|last2=Seth|first2=S.R.|last3=Venkataraman|first3=K.|title=Phloroacetophenone|journal=Organic Syntheses|date=1935|volume=15|page=70|doi=10.15227/orgsyn.015.0070}}</ref> and the [[Chemistry:Fries rearrangement|Fries rearrangement]].<ref name=Vogel />
* [[Chemistry:Ozonolysis|Ozonolysis]], and related dihydroxylation/oxidative sequences, cleave [[Chemistry:Alkene|alkene]]s to give aldehydes or ketones, depending on alkene substitution pattern.<ref>{{cite journal|last1=Tietze|first1=Lutz F.|last2=Bratz|first2=Matthias|title=Dialkyl Mesoxalates by Ozonolysis of Dialkyl Benzalmalonates: Dimethyl Mesoxalate|journal=Organic Syntheses|date=1993|volume=71|page=214|doi=10.15227/orgsyn.071.0214}}</ref>
* In the [[Chemistry:Kornblum–DeLaMare rearrangement|Kornblum–DeLaMare rearrangement]] ketones are prepared from peroxides and base.
* In the Ruzicka cyclization, cyclic ketones are prepared from [[Chemistry:Dicarboxylic acid|dicarboxylic acid]]s.
* In the [[Chemistry:Nef reaction|Nef reaction]], ketones form by [[Chemistry:Hydrolysis|hydrolysis]] of salts of secondary [[Chemistry:Nitro compound|nitro compound]]s.<ref>{{cite journal|last1=Heinzelman|first1=R. V.|title=o-Methoxyphenylacetone|journal=Organic Syntheses|date=1955|volume=35|page=74|doi=10.15227/orgsyn.035.0074}}</ref>
* In the [[Chemistry:Fukuyama coupling|Fukuyama coupling]], ketones form from a thioester and an organozinc compound.
* By the reaction of an acid chloride with [[Chemistry:Organocadmium compound|organocadmium compound]]s or [[Chemistry:Organocopper compound|organocopper compound]]s.
* The [[Chemistry:Dakin–West reaction|Dakin–West reaction]] provides an efficient method for preparation of certain methyl ketones from carboxylic acids.<ref>{{cite journal|last1=Wiley|first1=Richard H.|last2=Borum|first2=O. H.|title=3-Acetamido-2-butanone|journal=Organic Syntheses|date=1953|volume=33|page=1|doi=10.15227/orgsyn.033.0001}}</ref>
* Ketones can be prepared by the reaction of [[Chemistry:Grignard reagents|Grignard reagents]] with [[Chemistry:Nitrile|nitrile]]s, followed by hydrolysis.<ref>{{cite journal|last1=Moffett|first1=R. B.|last2=Shriner|first2=R. L.|title=ω-Methoxyacetophenone|journal=Organic Syntheses|date=1941|volume=21|page=79|doi=10.15227/orgsyn.021.0079}}</ref>
* By [[Chemistry:Decarboxylation|decarboxylation]] of carboxylic anhydride.
* Ketones can be prepared from haloketones in [[Chemistry:Reductive dehalogenation of halo ketones|reductive dehalogenation of halo ketones]].
* In [[Chemistry:Ketonic decarboxylation|ketonic decarboxylation]] symmetrical ketones are prepared from carboxylic acids.<ref name=Vogel /><ref>{{cite journal|last1=Thorpe|first1=J. F.|last2=Kon|first2=G. A. R.|title=Cyclopentanone|journal=Organic Syntheses|date=1925|volume=5|page=37|doi=10.15227/orgsyn.005.0037}}</ref>
* [[Chemistry:Hydrolysis|Hydrolysis]] of [[Chemistry:Saturated and unsaturated compounds|unsaturated]] [[Chemistry:Secondary|secondary]] amides,<ref>{{cite journal|last1=Herbst|first1=R. M.|last2=Shemin|first2=D.|title=Phenylpyruvic acid|journal=Organic Syntheses|date=1939|volume=19|page=77|doi=10.15227/orgsyn.019.0077}}</ref> [[Chemistry:Alpha and beta carbon|β]]-[[Chemistry:Keto acid|Keto acid]] esters,<ref name=Vogel /> or β-[[Chemistry:Diketone|diketone]]s (the [[Chemistry:Acetoacetic ester synthesis|acetoacetic ester synthesis]]).  
* [[Chemistry:Pinacol rearrangement|Acid-catalysed rearrangement]] of [[Chemistry:Diol#Vicinal diols|1,2-diols]],<ref name=Vogel /> or [[Chemistry:Criegee oxidation|Criegee oxidation]] of the same.

==Reactions==
[[File:Haller-Bauer reaction.png|thumb|500px|The Haller-Bauer reaction occurs between a ''non-enolizable'' ketone and a strong amide base. In this prototypical example involving benzophenone, the tetrahedral intermediate expels phenyl anion to give benzamide and benzene as the organic products]]
Ketones engage in many [[Chemistry:Organic reaction|organic reaction]]s. The most important reactions follow from the susceptibility of the carbonyl carbon toward [[Chemistry:Nucleophilic addition|nucleophilic addition]] and the tendency for the enolates to add to electrophiles.
Nucleophilic additions include in approximate order of their generality:<ref name=March/>
* With water (hydration) gives [[Chemistry:Geminal diol|geminal diol]]s, which are usually not formed in appreciable (or observable) amounts
* With an [[Chemistry:Acetylide|acetylide]] to give the α-hydroxyalkyne
* With [[Chemistry:Ammonia|ammonia]] or a primary amine gives an [[Chemistry:Imine|imine]]
* With secondary amine gives an [[Chemistry:Enamine|enamine]]
* With [[Chemistry:Grignard reagent|Grignard]] and [[Chemistry:Organolithium reagent|organolithium reagent]]s to give, after aqueous workup, a tertiary alcohol
* With an alcohols or [[Chemistry:Alkoxide|alkoxide]]s to gives the hemiketal or its conjugate base. With a [[Chemistry:Diol|diol]] to the ketal. This reaction is employed to protect ketones.
* With [[Chemistry:Sodium amide|sodium amide]] resulting in C–C bond cleavage with formation of the amide RCONH<sub>2</sub> and the alkane or arene R'H, a reaction called the Haller–Bauer reaction.<ref>[https://web.archive.org/web/20070910060716/http://nagoyaren.homeip.net/chem/reactions/123.htm Haller–Bauer Reaction]. homeip.net</ref>

* With strong [[Chemistry:Oxidizing agent|oxidizing agent]]s to give [[Chemistry:Carboxylic acid|carboxylic acid]]s. Ketones are generally oxidized under vigorous conditions, i.e., strong oxidizing agents and at elevated temperatures. Their oxidation involves carbon-carbon bond cleavage to afford a mixture of carboxylic acids having lesser number of carbon atoms than the parent ketone. 

[[File:Oxidation of Ketone.jpg|center|thumb|500px]]
* [[Chemistry:Electrophilic addition|Electrophilic addition]], reaction with an [[Chemistry:Electrophile|electrophile]] gives a resonance stabilized cation
* With phosphonium ylides in the [[Chemistry:Wittig reaction|Wittig reaction]] to give the [[Chemistry:Alkene|alkene]]s
* With [[Chemistry:Thiol|thiol]]s to give the [[Chemistry:Thioacetal|thioacetal]]
* With [[Chemistry:Hydrazine|hydrazine]] or 1-disubstituted [[Chemistry:Derivative|derivatives]] of hydrazine to give [[Chemistry:Hydrazone|hydrazone]]s.
* With a metal hydride gives a metal alkoxide salt, hydrolysis of which gives the alcohol, an example of ketone reduction
* With [[Chemistry:Halogen|halogen]]s to form an α-[[Chemistry:Haloketone|haloketone]], a reaction that proceeds via an [[Biology:Enol|enol]] (see [[Chemistry:Haloform reaction|Haloform reaction]])
* With [[Chemistry:Heavy water|heavy water]] to give an α-deuterated ketone
* Fragmentation in photochemical [[Physics:Norrish reaction|Norrish reaction]]
* Reaction of 1,4-aminodiketones to oxazoles by dehydration in the [[Chemistry:Robinson–Gabriel synthesis|Robinson–Gabriel synthesis]]
* In the case of aryl–alkyl ketones, with sulfur and an amine give amides in the Willgerodt reaction
* With [[Chemistry:Hydroxylamine|hydroxylamine]] to produce [[Chemistry:Oxime|oxime]]s
* With reducing agents to form secondary alcohols
* With [[Chemistry:Peroxy acid|peroxy acid]]s to form [[Chemistry:Ester|ester]]s in the [[Chemistry:Baeyer–Villiger oxidation|Baeyer–Villiger oxidation]]

==Biochemistry==
Ketones are pervasive in nature. The formation of organic compounds in [[Earth:Photosynthesis|photosynthesis]] occurs via the ketone ribulose-1,5-bisphosphate. Many sugars are ketones, known collectively as [[Chemistry:Ketose|ketose]]s. The best known ketose is [[Chemistry:Fructose|fructose]]; it mostly exists as a cyclic hemiketal, which masks the ketone functional group. [[Biology:Fatty acid synthesis|Fatty acid synthesis]] proceeds via ketones. Acetoacetate is an intermediate in the Krebs cycle which releases energy from sugars and carbohydrates.<ref>Nelson, D. L.; Cox, M. M. (2000) ''Lehninger, Principles of Biochemistry''. 3rd Ed. Worth Publishing: New York. {{ISBN|1-57259-153-6}}.</ref>

In medicine, [[Chemistry:Acetone|acetone]], acetoacetate, and beta-hydroxybutyrate are collectively called [[Biology:Ketone bodies|ketone bodies]], generated from [[Chemistry:Carbohydrate|carbohydrate]]s, [[Chemistry:Fatty acid|fatty acid]]s, and [[Chemistry:Amino acid|amino acid]]s in most [[Biology:Vertebrate|vertebrate]]s, including humans. Ketone bodies are elevated in the blood ([[Medicine:Ketosis|ketosis]]) after fasting, including a night of sleep; in both blood and [[Biology:Urine|urine]] in [[Medicine:Starvation|starvation]]; in [[Medicine:Hypoglycemia|hypoglycemia]], due to causes other than [[Medicine:Hyperinsulinemic hypoglycemia|hyperinsulinism]]; in various inborn errors of metabolism, and intentionally induced via a [[Chemistry:Ketogenic diet|ketogenic diet]], and in ketoacidosis (usually due to [[Medicine:Diabetes|diabetes]] mellitus). Although ketoacidosis is characteristic of decompensated or untreated [[Medicine:Type 1 diabetes|type 1 diabetes]], ketosis or even ketoacidosis can occur in [[Medicine:Diabetes mellitus type 2|type 2 diabetes]] in some circumstances as well.

==Applications==
Ketones are produced on massive scales in industry as solvents, polymer precursors, and pharmaceuticals. In terms of scale, the most important ketones are [[Chemistry:Acetone|acetone]], methylethyl ketone, and [[Chemistry:Cyclohexanone|cyclohexanone]].<ref name="Ullmann">{{Cite book |doi=10.1002/14356007.a15077|chapter=Ketones|title=Ullmann's Encyclopedia of Industrial Chemistry|year=2000|last1=Siegel|first1=Hardo|last2=Eggersdorfer|first2=Manfred|doi-broken-date=1 August 2023|isbn=9783527306732}}</ref> They are also common in biochemistry, but less so than in organic chemistry in general. The [[Physics:Combustion|combustion]] of hydrocarbons is an uncontrolled oxidation process that gives ketones as well as many other types of compounds.

==Toxicity==
Although it is difficult to generalize on the [[Medicine:Toxicity|toxicity]] of such a broad class of compounds, simple ketones are, in general, not highly toxic. This characteristic is one reason for their popularity as solvents. Exceptions to this rule are the [[Chemistry:Saturated and unsaturated compounds|unsaturated]] ketones such as [[Chemistry:Methyl vinyl ketone|methyl vinyl ketone]] with {{LD50}} of 7&nbsp;mg/kg (oral).<ref name="Ullmann" />

==See also==
*[[Chemistry:Diketone|Diketone]]
*[[Biology:Ketone bodies|Ketone bodies]]
*[[Chemistry:Thioketone|Thioketone]]
*[[Chemistry:Triketone|Triketone]]
*[[Chemistry:Ynone|Ynone]]
*[[Medicine:Ketosis|Ketosis]]

==References==
{{Reflist}}

==External links==
{{Aldehyde-ketone transferases}}
{{Intramolecular oxidoreductases}}
{{Functional Groups}}
{{Cholesterol and steroid metabolism enzymes}}

[[Category:Functional groups]]
[[Category:Ketones| ]]

{{Sourceattribution|Ketone}}