Propionic acid
316076
223743401
2008-07-05T15:48:04Z
86.130.120.230
not a NSAID itself, so removed
{{Chembox new
| Name = Propionic acid
| ImageFile = Propionic acid structure.png
| ImageSize = 250px
| ImageName = Propionic acid
| IUPACName = propanoic acid
| OtherNames = ethanecarboxylic acid
| Section1 = {{Chembox Identifiers
| SMILES = CCC(=O)O
| CASNo = 79-09-4
| RTECS = UE5950000
}}
| Section2 = {{Chembox Properties
| Formula = CH<sub>3</sub>CH<sub>2</sub>COOH
| MolarMass = 74.08 g/mol
| Appearance = colourless liquid
| Density = 0.99 g/cm³, liquid
| Solubility = miscible
| MeltingPt = -21 °C (252 K)
| BoilingPt = 141 °C (414 K)
| pKa = 4.88
| Viscosity = 10 [[Pascal second|mPa·s]]
}}
| Section3 = {{Chembox Structure
| Dipole = 0.63 [[Debye|D]]
}}
| Section7 = {{Chembox Hazards
| ExternalMSDS = [[Propionic acid chemdata supplement#Material Safety Data Sheet|External MSDS]]
| MainHazards = Corrosive
| NFPA-H = 3
| NFPA-F = 2
| NFPA-R =
| FlashPt = 54°C
| RPhrases = {{R34}}
| SPhrases = {{S1/2}}, {{S23}}, {{S36}}, {{S45}}
}}
| Section8 = {{Chembox Related
| OtherAnions = [[sodium propionate]]
| Function = [[carboxylic acid|carboxylic acids]]
| OtherFunctn = [[acetic acid]]<br />[[butyric acid]]
| OtherCpds = [[1-Propanol|1-propanol]]<br />[[propionaldehyde]]<br />[[methyl propionate]]<br />[[propionic anhydride]]}}
}}
'''Propionic acid''' (systematically named '''propanoic acid''') is a naturally-occurring [[carboxylic acid]] with [[chemical formula]] [[Carbon|C]][[Hydrogen|H]]<sub>3</sub>CH<sub>2</sub>C[[Oxygen|O]]OH. In the pure state, it is a colorless, corrosive liquid with a pungent odor. The [[anion]] CH<sub>3</sub>CH<sub>2</sub>COO<sup>−</sup> as well as the [[salt (chemistry)|salt]]s and [[ester]]s of propionic acid are known as [[propionate]]s (or propanoates).
==History==
Propionic acid was first described in [[1844]] by [[Johann Gottlieb]], who found it among the degradation products of [[sugar]]. Over the next few years, other chemists produced propionic acid in various other ways, none of them realizing they were producing the same substance. In [[1847]], the French chemist [[Jean-Baptiste Dumas]] established that all the acids were the same compound, which he called propionic acid, from the [[Greek language|Greek]] words ''protos'' = "first" and ''pion'' = "fat," because it was the smallest H(CH<sub>2</sub>)<sub>''n''</sub>COOH acid that exhibited the properties of the other [[fatty acid]]s, such as producing an oily layer when salted out of water and having a [[soap]]y [[potassium]] salt.
==Properties==
Propionic acid has physical properties intermediate between those of the smaller carboxylic acids, [[formic acid|formic]] and [[acetic acid]], and the larger [[fatty acid]]s. It is miscible with water, but it can be removed from water by adding salt. As with acetic and formic acids, its vapor grossly violates the [[ideal gas law]] because it does not consist of individual propionic acid molecules, but instead of [[hydrogen bond]]ed pairs of molecules. It also undergoes this pairing in the liquid state.
Propionic acid displays the general properties of carboxylic acids, and, like most other carboxylic acids, it can form [[amide]], [[ester]], [[acid anhydride|anhydride]], and [[acyl chloride|chloride]] derivatives. It can undergo alpha-[[halogenation]] with [[bromine]] in the presence of [[phosphorus tribromide|PBr<sub>3</sub>]] as [[catalyst]] (the [[Hell-Volhard-Zelinsky halogenation|HVZ reaction]]) to form CH<sub>3</sub>CHBrCOOH.
==Production==
In industry, propionic acid is main produced by the hydrocarboxylation of [[ethylene]] using [[nickel carbonyl]] as the catalyst:<ref>W. Bertleff, M. Roeper, X. Sava, “Carbonylation” in Ullmann’s Encyclopedia of Chemical Technology Wiley-VCH: Weinheim, 2003. DOI: 10.1002/14356007.a05 217.</ref>
:RCH=CH<sub>2</sub> + H<sub>2</sub>O + CO → CH<sub>3</sub>CH<sub>2</sub>CO<sub>2</sub>H
It is also produced by the aerobic [[oxidation]] of [[propionaldehyde]]. In the presence of [[cobalt]] or [[manganese]] [[ion]]s, this reaction proceeds rapidly at temperatures as mild as 40-50°C:
:[[propionaldehyde|CH<sub>3</sub>CH<sub>2</sub>CHO]] + ½ [[oxygen|O<sub>2</sub>]] → CH<sub>3</sub>CH<sub>2</sub>COOH
Large amounts of propionic acid were once produced as a byproduct of acetic acid manufacture. Current world's largest producer is [[BASF]], with approximately 80 ktpa production capacity.
Propionic acid is produced biologically as its coenzyme A ester, [[propionyl-CoA]], from the [[metabolism|metabolic]] breakdown of fatty acids containing [[odd number]]s of [[carbon]] atoms, and also it the breakdown of some [[amino acid]]s. [[Bacterium|Bacteria]] of the genus ''[[Propionibacterium]]'' produce propionic acid as the end product of their [[Anaerobic respiration|anaerobic]] metabolism. This class of bacteria is commonly found in the stomachs of [[ruminant]]s and the [[Propionibacterium acnes|sweat glands of humans]], and their activity is partially responsible for the odor of both [[Swiss cheese]] and [[sweat]].
==Uses==
Propionic acid inhibits the growth of [[mold]] and some [[bacterium|bacteria]]. As a result, most propionic acid produced is used as a [[preservative]] for both animal feed and food for human consumption, and can be used as a preservative for Ballistics Gel. For animal feed, it is used either directly or as its [[ammonium]] salt. In human foods, especially [[bread]] and other baked goods, it is used as its [[sodium]] or [[calcium]] salt. Similar usage occurs in some of the older anti-fungal foot powders.
Propionic acid is also useful as a chemical intermediate. It can be used to modify synthetic [[cellulose]] fibers. It is also used to make [[pesticide]]s and [[pharmaceutical]]s. The [[ester]]s of propionic acid are sometimes used as [[solvent]]s or artificial flavorings.
==Safety==
The chief danger from propionic acid is chemical burns that can result from contact with the concentrated liquid. In studies on laboratory animals, the only adverse health effect associated with long-term exposure to small amounts of propionic acid has been [[ulcer]]ation of the [[esophagus]] and [[stomach]] from consuming a corrosive substance. No toxic, [[mutagen]]ic, [[carcinogen]]ic, or reproductive effects have ever been observed. In the body, propionic acid is readily metabolized, so it does not bioaccumulate.
A recent publication by MacFabe and colleagues found that intraventricular infusions of propionic acid produced reversible behavior that was very similar to that seen in [[autism]]. Behaviors included: hyperactivity, dystonia, turning, retropulsion. In addition, the treated rats demonstrated caudate spiking and the progressive development of limbic kindled seizures. The paper concludes that this is an excellent animal model of autism and warrants further study.<ref name = macfabe/>
==Metabolism==
The metabolism of propionic acid begins with its conversion to propionyl [[coenzyme A]] (propionyl-CoA), the usual first step in the metabolism of [[carboxylic acid]]s.
Since propionic acid has three carbons, propionyl-CoA can enter neither [[beta oxidation]] nor the [[citric acid cycle]]
In most [[vertebrate]]s, propionyl-CoA is [[carboxylation|carboxylated]] to D-methylmalonyl-CoA, [[Isomerisation|isomerised]] to L-methylmalonyl-CoA, and rearranged to yield [[succinyl-CoA]] via a [[vitamin B12]]-dependent enzyme. Succinyl-CoA is an intermediate of the citric acid cycle and can be readily incorporated there.
In propionic acidemia, propionate acts as a metabolic toxin in liver cells by accumulating in mitochondria as propionyl-CoA and its derivative, methylcitrate, two tricarboxylic acid cycle inhibitors. Propionate is metabolized oxidatively by glia, which suggests astrocytic vulnerability in propionic acidemia when intramitochondrial propionyl-CoA may accumulate. Propionic acidemia may alter both neuronal and glial gene expression by affecting histone acetylation.<ref name = macfabe>{{cite journal
| author = D. F. MacFabe, D. P. Cain, K. Rodriguez-Capote, A. E. Franklin, J. E. Hoffman, F. Boon, A. R. Taylor, M. Kavaliers and K.-P. Ossenkopp
| journal = Behavioral Brain Research
| title = Neurobiological effects of intraventricular propionic acid in rats: Possible role of short-chain fatty acids on the pathogenesis and characteristics of autism spectrum disorders
| year = 2007
| volume = 176
| issue = 1
| pages = 149–169
| doi = 10.1016/j.bbr.2006.07.025
| url = }}</ref><ref>{{cite journal
| author = N. H. T. Nguyen, C. Morland, S. Villa Gonzalez, F. Rise, J. Storm-Mathisen, V. Gundersen, B. Hassel
| journal = Journal of Neurochemistry
| title = Propionate increases neuronal histone acetylation, but is metabolized oxidatively by gli. Relevance for propionic acidemia
| year = 2007
| volume = 101
| issue = 3
| pages = 806–814
| doi = 10.1111/j.1471-4159.2006.04397.x
| url = }}</ref>
==Human occurrence==
The human [[skin]] is host to a species of bacteria known as ''[[Propionibacterium acnes]]'', which is named after its ability to produce propionic acid. This bacteria lives mainly in the [[sebaceous glands]] of the skin and is one of the principle causes of [[acne]].
==References==
{{Reflist}}
==External links==
* [http://webbook.nist.gov/chemistry/ NIST Standard Reference Database]
* [http://ecb.jrc.it/ European Chemicals Bureau]
* [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc08/icsc0806.htm International Chemical Safety Card 0806]
* [http://www.cdc.gov/niosh/npg/npgd0529.html NIOSH Pocket Guide to Chemical Hazards]
* [http://www.basf.com/static/OpenMarket/Xcelerate/Preview_cid-974236976155_pubid-974236725646_c-Article.html Technical data of propionic acid of BASF]
[[Category:Propionates]]
[[Category:Carboxylic acids]]
[[Category:Acids]]
[[Category:Analgesics]]
[[de:Propionsäure]]
[[el:Προπιονικό οξύ]]
[[es:Ácido propílico]]
[[fr:Acide propanoïque]]
[[it:Acido propionico]]
[[la:Acidum propionicum]]
[[lv:Propionskābe]]
[[nl:Propaanzuur]]
[[ja:プロピオン酸]]
[[pl:Kwas propionowy]]
[[pt:Ácido propanóico]]
[[ru:Пропионовая кислота]]
[[fi:Propionihappo]]
[[sv:Propansyra]]
[[vi:Axít prôpionic]]
[[zh:丙酸]]