Ketone 16803 225983662 2008-07-16T09:25:37Z Gerakibot 4112738 robot Adding: [[el:Κετόνη]] [[Image:ketone-displayed.png|150px|right|thumb|Ketone group]] A '''ketone''' (pronounced as ''key tone'') is either the [[functional group]] characterized by a [[carbonyl]] group (O=C) linked to two other [[carbon]] atoms or a [[chemical compound]] that contains a carbonyl group. A ketone can be generally represented by the [[chemical formula]]: :R<sub>1</sub>([[carbon|C]][[oxygen|O]])R<sub>2</sub>. A carbonyl carbon bonded to two carbon atoms distinguishes ketones from [[carboxylic acid]]s, [[aldehyde]]s, [[ester]]s, [[amide]]s, and other [[oxygen]]-containing compounds. The double-bond of the carbonyl group distinguishes ketones from [[alcohol]]s and [[ether]]s. The simplest ketone is [[acetone]] (systematically named propan-2-one<ref>The position of the carbonyl group is usually denoted by a number; in propanone there can only be one position. While propanone or propan-2-one is how the molecule should be named according to systematic nomenclature, the name "acetone" is retained in official IUPAC nomenclature</ref>). The carbon atom adjacent to a carbonyl group is called the α-carbon. Hydrogens attached to this carbon are called α-hydrogens. In the presence of an acid catalyst the ketone is subjected to so-called [[keto-enol tautomerism]]. The reaction with a [[strong base]] gives the corresponding [[enolate]]. A [[diketone]] is a compound containing two ketone groups. == Nomenclature == [[Image:Acetone-structural.png|150px|right|thumb|[[Acetone]], the simplest ketone]]In general, ketones are named using [[IUPAC nomenclature]] by changing the suffix ''-e'' of the parent [[alkane]] to ''-one''. For common ketones, some traditional names such as [[acetone]] and [[benzophenone]] predominate, and these 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 texts use names such as propanone. '''Oxo''' is the formal [[IUPAC]] nomenclature for a ketone [[functional group]]. However, other prefixes are also used by various books and journals. For some common chemicals (mainly in biochemistry), '''keto''' or '''oxo''' is the term used to describe the ketone (also known as alkanone) [[functional group]]. '''Oxo''' also refers to a single oxygen atom coordinated to a transition metal (a metal oxo). ==Physical properties== A carbonyl group is [[polar molecule|polar]]. This makes ketones [[polar compound]]s. The carbonyl groups interact with water by [[hydrogen bond]]ing, and ketones are soluble in water. It is a hydrogen-bond acceptor, but not a hydrogen-bond donor, and cannot hydrogen-bond to itself. This makes ketones more volatile than [[alcohol]]s and [[carboxylic acid]]s of similar [[molecular weight]]. == Acidity == The α-hydrogen of a ketone is far more acidic ([[Pka|pKa]] ≈ 20) than the hydrogen of a regular alkane (pKa ≈ 50). This is due to resonance stabilization of the [[enolate ion]] that is formed through dissociation. The relative acidity of the α-hydrogen is important in the enolization reactions of ketones and other carbonyl compounds. ==Spectroscopic properties== [[Spectroscopy]] is an important means for identifying ketones. Ketones and aldehydes will display a significant peak in [[infrared spectroscopy]], at around 1700 [[wavenumber|cm<sup>−1</sup>]] (slightly higher or lower, depending on the chemical environment) == Synthesis ==<!-- This section is linked from [[Organic reaction]] --> Several methods exist for the preparation of ketones in the laboratory: * Ketones can be created by [[oxidation]] of secondary [[alcohol]]s. The process requires a strong [[organic oxidation|oxidizing]] agent such as [[potassium permanganate]], [[potassium dichromate]] or other agents containing [[chromium|Cr(VI)]]. The alcohol is oxidized by heating under [[reflux]] in acidified solution. For example [[propan-2-ol]] is oxidised to [[acetone]]: :H<sub>3</sub>C-CH(OH)-CH<sub>3</sub> → H<sub>3</sub>C-CO-CH<sub>3</sub> :Two atoms of hydrogen are removed, leaving a single oxygen atom double-bonded to a carbon atom. * Ketones are also prepared by [[Gem halide hydrolysis]]. * Alkynes can be turned into [[enol]]s through a [[hydration reaction]] in the presence of an acid and [[Mercury(II) sulfate| HgSO<sub>4</sub> ]], and subsequent enol-keto tautomerization gives a ketone. This always produces a ketone, even with a terminal alkyne, and [[Sia2BH]] is needed to get an aldehyde from an alkyne * Aromatic ketones can be prepared in the [[Friedel-Crafts reaction]], the related [[Houben-Hoesch reaction]] and the [[Fries rearrangement]]. * In the [[Kornblum–DeLaMare rearrangement]] ketones are prepared from peroxides and base * In the [[Ruzicka cyclization]], cyclic ketones are prepared from dicarboxylic acids. * In the [[Nef reaction]], ketones form by hydrolysis of salts of secondary nitro compounds * In the [[Fukuyama coupling]], ketones form from a thioester and a organozinc compound * Ketones are also prepeared by the reaction of [[acid chloride]] with [[organocadmium compound]]s or [[organocopper compound]]s. == Reactions == Ketones engage in many [[organic reaction]]s: * [[Nucleophilic addition]]. The reaction of a ketone with a [[nucleophile]] gives a [[tetrahedral carbonyl addition compound]]. ** the reaction with the [[anion]] of a terminal [[alkyne]] gives a [[hydroxyalkyne]] ** the reaction with [[ammonia]] or a [[primary amine]] gives an [[imine]] + water ** the reaction with [[secondary amine]] gives an [[enamine]] + water ** the reaction with a [[Grignard reagent]] gives a [[magnesium alkoxide]] and after aqueous workup a [[tertiary alcohol]] ** the reaction with an [[organolithium reagent]] also gives a tertiary alcohol ** the reaction with an [[alcohol]], an [[acid]] or [[base (chemistry)|base]] gives a [[hemiketal]] + water and further reaction with an alcohol gives the [[ketal]] + water. This is a [[carbonyl]]-protecting reaction. ** reaction of RCOR' with [[sodium amide]] results in cleavage with formation of the amide RCONH2 and the alkane R'H, a reaction called the '''Haller-Bauer reaction''' (1909) <ref>[http://nagoyaren.homeip.net/chem/reactions/123.htm Haller-Bauer Reaction<!-- Bot generated title -->]</ref> * [[Electrophilic addition]], reaction with an [[electrophile]] gives a resonance stabilized cation. * the reaction with phosphonium ylides in the [[Wittig reaction]] gives [[alkene]]s * reaction with water gives [[geminal]] [[diol]]s * reaction with [[thiol]]s gives a [[thioacetal]] * reaction with [[hydrazine]] or [[derivative]]s of hydrazine gives [[hydrazone]]s * reaction with a [[metal hydride]] gives a [[metal alkoxide salt]] and then with water an [[alcohol]] * reaction of an [[enol]] with [[halogen]]s to form α-[[haloketone]] * a reaction at an α-carbon is the reaction of a ketone with [[heavy water]] to give a [[deuteration|deuterated]] ketone-d. * fragmentation in photochemical [[Norrish reaction]] * reaction with halogens and base of methyl ketones in the [[Haloform reaction]] * reaction of 1,4-aminodiketones to [[oxazoles]] by dehydration in the [[Robinson-Gabriel synthesis]] * reaction of aryl alkyl ketones with sulfur and an amine to amides in the [[Willgerodt reaction]] == Biochemistry== [[Acetone]], [[acetoacetate]] and [[beta-hydroxybutyrate]] are ketones (or [[ketone bodies]]) generated from [[carbohydrate]]s, [[fatty acid]]s and [[amino acid]]s in humans and most [[vertebrate]]s. Ketones are elevated in [[blood]] after fasting including a night of sleep, and in both blood and [[urine]] in [[starvation]], [[hypoglycemia]] due to causes other than [[hyperinsulinemic hypoglycemia|hyperinsulinism]], various [[inborn error of metabolism|inborn errors of metabolism]], and [[ketoacidosis]] (usually due to [[diabetes mellitus]]). Although ketoacidosis is characteristic of decompensated or untreated [[type 1 diabetes]], ketosis or even ketoacidosis can occur in [[Diabetes mellitus type 2|type 2 diabetes]] in some circumstances as well. Acetoacetate and beta-hydroxybutyrate are an important fuel for many tissues, especially during fasting and starvation. The brain, in particular, relies heavily on ketone bodies as a substrate for [[lipid]] synthesis and for energy during times of reduced food intake. At the [[NIH]], Dr. Richard Veech refers to ketones as "magic" in their ability to increase metabolic efficiency, while decreasing production of free radicals, the damaging byproducts of normal metabolism. His work has shown that ketone bodies may treat neurological diseases such as Alzheimer's and Parkinson's disease,<ref>{{cite journal | author = Y. Kashiwaya, T. Takeshima, N. Mori, K. Nakashima, K. Clarke and R. L. Veech | title = D-beta -Hydroxybutyrate protects neurons in models of Alzheimer's and Parkinson's disease | year = 2000 | journal = [[PNAS]] | volume = 97 | issue = 10 | pages = 5440–5444 | doi = 10.1073/pnas.97.10.5440 | pmid = 10805800}}</ref> and the heart and brain operate 25% more efficiently using ketones as a source of energy.<ref>{{cite journal | author = Y. Kashiwaya, K. Sato, N. Tsuchiya, S. Thomas, D. A. Fell, R. L. Veech and J. V. Passonneau | title = Control of glucose utilization in working perfused rat heart | year = 1994 | journal = [[J. Biol. Chem.]] | volume = 269 | issue = 41 | pages = 25502–25514 | doi = | url = http://www.jbc.org/cgi/content/abstract/269/41/25502 | pmid = 7929251 }}</ref> Research has also shown ketones play a role in reducing epileptic siezures with the so-called high-fat, near-zero carbohydrate Ketogenic Diet. [http://www.vanderbilt.edu/AnS/psychology/health_psychology/ketogenic_diets.htm] ==Applications == Ketones are often used in [[perfume]]s and [[paint]]s to stabilize the other ingredients so that they don't degrade as quickly over time. Other uses are as solvents and intermediates in chemical industry. Examples of ketones are [[acetone]], [[acetophenone]], and [[methyl ethyl ketone]]. ==See also== {{wiktionary}} * [[List of publications in chemistry#Organic chemistry|List of publications in organic chemistry]] *[[Ketosis]] *[[Ketone bodies]] (Medical term referring to all or either of the three ketones occurring in the body). == References == <references /> {{Functional Groups}} [[Category:Functional groups]] [[Category:Ketones]] [[ar:كيتون]] [[bg:Кетон]] [[ca:Cetona]] [[cs:Ketony]] [[da:Keton]] [[de:Ketone]] [[et:Ketoonid]] [[el:Κετόνη]] [[es:Cetona (química)]] [[eo:Ketono]] [[fa:کتون]] [[fr:Cétone]] [[ko:케톤]] [[hr:Keton]] [[id:Keton]] [[it:Chetoni]] [[he:קטון]] [[la:Ketonum]] [[lv:Ketoni]] [[lt:Ketonai]] [[hu:Keton]] [[mk:Кетон]] [[ms:Keton]] [[nl:Keton]] [[ja:ケトン]] [[no:Keton]] [[pl:Ketony]] [[pt:Cetona]] [[ro:Cetonă]] [[ru:Кетоны]] [[sk:Ketón]] [[sr:Кетон]] [[fi:Ketoni]] [[sv:Keton]] [[tr:Keton]] [[zh:酮]]