Propionic acid

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Propionic acid
Simplified skeletal formula
Simplified skeletal formula
Full structural formula
Full structural formula
Ball-and-stick model
Ball-and-stick model
Space-filling model
Space-filling model
Names
Preferred IUPAC name
Propanoic acid
Other names
Carboxyethane
Ethanecarboxylic acid
Ethylformic acid
Metacetonic acid
Methylacetic acid
C3:0 (Lipid numbers)
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard
 100.001.070 Edit this at Wikidata
EC Number
  • Propionic acid: 201-176-3
E number E280 (preservatives)
IUPHAR/BPS
  • Propionic acid: 1062
RTECS number
  • Propionic acid: UE5950000
UNII
  • InChI=1S/C3H6O2/c1-2-3(4)5/h2H2,1H3,(H,4,5) checkY
    Key: XBDQKXXYIPTUBI-UHFFFAOYSA-N checkY
  • Propionic acid: CCC(=O)O
  • Propionate: CCC(=O)[O-]
Properties
C3H6O2
Molar mass 74.079 g·mol−1
Appearance Colorless, oily liquid[1]
Odor Pungent, rancid, unpleasant[1]
Density 0.98797 g/cm3[2]
Melting point −20.5 °C (−4.9 °F; 252.7 K)[8]
Boiling point 141.15 °C (286.07 °F; 414.30 K)[8]
Sublimes at −48 °C
ΔsublHo = 74 kJ/mol[3]
8.19 g/g (−28.3 °C)
34.97 g/g (−23.9 °C)
Miscible (≥ −19.3 °C)[4]
Solubility Miscible in EtOH, ether, CHCl
3[5]
log P 0.33[6]
Vapor pressure 0.32 kPa (20 °C)[7]
0.47 kPa (25 °C)[6]
9.62 kPa (100 °C)[3]
4.45·10−4 L·atm/mol[6]
Acidity (pKa) 4.88[6]
-43.50·10−6 cm3/mol
1.3843[2]
Viscosity 1.175 cP (15 °C)[2]
1.02 cP (25 °C)
0.668 cP (60 °C)
0.495 cP (90 °C)[6]
Structure
Monoclinic (−95 °C)[9]
P21/c[9]
a = 4.04 Å, b = 9.06 Å, c = 11 Å[9]
α = 90°, β = 91.25°, γ = 90°
0.63 D (22 °C)[2]
Thermochemistry
152.8 J/mol·K[5][3]
191 J/mol·K[3]
Std enthalpy of
formation
(ΔfH⦵298)
 −510.8 kJ/mol[3]
Std enthalpy of
combustion
(ΔcH⦵298)
 1527.3 kJ/mol[2][3]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Corrosive
GHS labelling:
GHS02: FlammableGHS05: Corrosive[7]
Danger
H314[7]
P280, P305+P351+P338, P310[7]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
2
0
Flash point 54 °C (129 °F; 327 K)[7]
512 °C (954 °F; 785 K)
Lethal dose or concentration (LD, LC):
1370 mg/kg (mouse, oral)[5]
NIOSH (US health exposure limits):
PEL (Permissible)
 none[1]
REL (Recommended)
 TWA 10 ppm (30 mg/m3) ST 15 ppm (45 mg/m3)[1]
IDLH
(Immediate danger)
 N.D.[1]
Related compounds
Acetic acid
Lactic acid
3-Hydroxypropionic acid
Tartronic acid
Acrylic acid
Butyric acid
Related compounds
 1-Propanol
Propionaldehyde
Sodium propionate
Propionic anhydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Propionic acid (

salts and esters
of propionic acid are known as propionates or propanoates.

History

Propionic acid was first described in 1844 by

salt.[11]

Properties

Propionic acid has physical properties intermediate between those of the smaller carboxylic acids, formic and acetic acids, and the larger fatty acids. It is miscible with water, but can be removed from water by adding salt. As with acetic and formic acids, it consists of hydrogen bonded pairs of molecules in both the liquid and the vapor.

Propionic acid displays the general properties of carboxylic acids: it can form

catalysed by phosphorus tribromide, in this case to form 2-bromopropanoic acid, CH
3CHBrCOOH.[12] This product has been used to prepare a racemic mixture of alanine by ammonolysis.[13][14]

Manufacture

Chemical

In industry, propionic acid is mainly produced by the

nickel carbonyl as the catalyst:[15]

Hydrocarboxylation of ethene with carbon monoxide and water to form propionic acid in the presence of nickel tetracarbonyl as catalyst

It is also produced by the aerobic

oxidation of propionaldehyde. In the presence of cobalt or manganese
salts (manganese propionate is most commonly used), this reaction proceeds rapidly at temperatures as mild as 40–50 °C:

Liquid-phase oxidation of propionaldehyde with atmospheric oxygen to form propionic acid in the presence of manganese(II)-propionate as catalyst

Large amounts of propionic acid were once produced as a byproduct of acetic acid manufacture. At the current time, the world's largest producer of propionic acid is BASF, with approximately 150 kt/a production capacity.

Biotechnological

Biotechnological production of propionic acid mainly uses Propionibacterium strains.[16] However, large scale production of propionic acid by Propionibacteria faces challenges such as severe inhibition of end-products during cell growth and the formation of by-products (acetic acid and succinic acid).[17] One approach to improve productivity and yield during fermentation is through the use of cell immobilization techniques, which also promotes easy recovery, reuse of the cell biomass and enhances microorganisms' stress tolerance.[18] In 2018, 3D printing technology was used for the first time to create a matrix for cell immobilization in fermentation. Propionic acid production by Propionibacterium acidipropionici immobilized on 3D-printed nylon beads was chosen as a model study. It was shown that those 3D-printed beads were able to promote high density cell attachment and propionic acid production, which could be adapted to other fermentation bioprocesses.[19] Other cell immobilization matrices have been tested, such as recycled-glass Poraver and fibrous-bed bioreactor.[20][21]

Alternative methods of production have been trialled, by genetically engineering strains of Escherichia coli to incorporate the necessary pathway, the Wood-Werkman cycle.[22]

Industrial uses

Propionic acid inhibits the growth of

mold and some bacteria at levels between 0.1 and 1% by weight. As a result, some propionic acid produced is consumed as a preservative for both animal feed and food for human consumption. For animal feed, it is used either directly or as its ammonium salt. This application accounts for about half of the world production of propionic acid. The antibiotic monensin is added to cattle feed to favor propionibacteria over acetic acid producers in the rumen; this produces less carbon dioxide and feed conversion is better. Another major application is as a preservative in baked goods, which use the sodium and calcium salts.[15] As a food additive, it is approved for use in the EU,[23] US,[24] Australia and New Zealand.[25]

Propionic acid is also useful as an intermediate in the production of other chemicals, especially polymers.

pharmaceuticals. The esters of propionic acid have fruit-like odors and are sometimes used as solvents or artificial flavorings.[15]

In

biogas plants, propionic acid is a common intermediate product, which is formed by fermentation with propionic acid bacteria. Its degradation in anaerobic environments (e.g. biogas plants) requires the activity of complex microbial communities.[26]

In production of the Jarlsberg cheese a propionic acid bacteria is used to give both taste and holes.[27]

Biology

Propionic acid is produced biologically as its coenzyme A ester,

sweat
.

The metabolism of propionic acid begins with its conversion to propionyl

isomerised to L-methylmalonyl-CoA. A vitamin B12-dependent enzyme catalyzes rearrangement of L-methylmalonyl-CoA to succinyl-CoA, which is an intermediate of the citric acid cycle and can be readily incorporated there.[28]

Propionic acid serves as a substrate for

upregulate endogenous glucose production via increases in norepinephrine and glucagon, suggesting that chronic ingestion of propionic acid may have adverse metabolic consequences.[32]

In

autism in rats.[33]

Human occurrence

The human skin is host of several species of Propionibacteria. The most notable one is the

gut microbiota in response to indigestible carbohydrates (dietary fiber) in the diet.[36][37] The role of the gut microbiota and their metabolites, including propionate, in mediating brain function has been reviewed.[38]

A study in mice suggests that propionate is produced by the bacteria of the genus Bacteroides in the gut, and that it offers some protection against Salmonella there.[39] Another study finds that fatty acid propionate can calm the immune cells that drive up blood pressure, thereby protecting the body from damaging effects of high blood pressure.[40]

Bacteriology

The Bacteria species Coprothermobacter platensis produces propionate when fermenting gelatin.[41]

Propionate salts and esters

The propionate

carboxylate salt or ester
of propionic acid. In these compounds, propionate is often written in shorthand, as CH
3CH
2CO
2 or simply EtCO
2.

Propionates should not be confused with propenoates (commonly known as acrylates), the ions/salts/esters of propenoic acid (also known as 2-propenoic acid or acrylic acid).

Examples

Salts

Esters

See also

References

  1. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0529". National Institute for Occupational Safety and Health (NIOSH).
  2. ^
    ISBN 978-0323151030
    .
  3. ^ a b c d e f Propanoic acid in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 13 June 2014)
  4. ^ Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). D. Van Nostrand Company. p. 569.
  5. ^ a b c "chemister.ru (archived copy)". Archived from the original on 9 October 2016. Retrieved 13 June 2014.
  6. ^ a b c d e CID 1032 from PubChem
  7. ^ a b c d e Sigma-Aldrich Co., Propionic acid. Retrieved on 13 June 2014.
  8. ^
    ISBN 978-1-4200-9084-0
    .
  9. ^
    doi:10.1107/S0365110X62003278
    .
  10. ^ Johann Gottlieb (1844) "Ueber die Einwirkung von schmelzendem Kalihydrat auf Rohrzucker, Gummi, Stärkmehl und Mannit" (On the effect of molten potassium hydroxide on raw sugar, rubber, starch powder, and mannitol), Annalen der Chemie und Pharmacie, 52 : 121–130. After combining raw sugar with an excess of potassium hydroxide and distilling the result, Gottlieb obtained a product that he called "Metacetonsäure" (meta-acetone acid) on p. 122: "Das Destillat ist stark sauer und enthält Ameisensäure, Essigsäure und eine neue Säure, welche ich, aus unten anzuführenden Gründen, Metacetonsäure nenne." (The distillate is strongly acidic and contains formic acid, acetic acid, and a new acid, which for reasons to be presented below I call "meta-acetone acid".)
  11. ^ Dumas, Malaguti, and F. Leblanc (1847) "Sur l'identité des acides métacétonique et butyro-acétique" [On the identity of metacetonic acid and butyro-acetic acid], Comptes rendus, 25 : 781–784. Propionic acid is named on p. 783: "Ces caractères nous ont conduits à désigner cet acide sous le nom d'acide propionique, nom qui rappelle sa place dans la séries des acides gras: il en est le premier." (These characteristics led us to designate this acid by the name of propionic acid, a name that recalls its place in the series of fatty acids: it is the first of them.)
  12. doi:10.15227/orgsyn.011.0020
    ; Collected Volumes, vol. 2, p. 93.
  13. doi:10.1021/ja01284a510
    .
  14. doi:10.15227/orgsyn.009.0004
    ; Collected Volumes, vol. 1, p. 21.
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    ISBN 978-3527306732
    .
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  18. S2CID 860853
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  20. S2CID 29658955
    .
  21. PMID 15977254
    .
  22. S2CID 203438727
    .
  23. ^ "Current EU approved additives and their E Numbers". UK Food Standards Agency. Retrieved 27 October 2011.
  24. ^ "Listing of Food Additives Status Part II". US Food and Drug Administration. Retrieved 27 October 2011.
  25. ^ "Standard 1.2.4 – Labelling of ingredients". Australia New Zealand Food Standards Code. Comlaw.au. 8 September 2011. Retrieved 27 October 2011.
  26. PMID 27364538
    .
  27. ^ www.jarlsberg.com quote: " In the production of Jarlsberg®, propionic acid bacteria (the Secret Recipe!) is used to give the cheese its characteristic taste and holes."
  28. OCLC 55476414
    .
  29. S2CID 21117076
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  30. PMID 27002151
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  31. doi:10.1016/S0021-9258(18)88686-0
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  32. PMID 31019023
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  33. ^
    S2CID 3054752
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  34. S2CID 514557
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  35. PMID 15556721
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  36. PMID 27617197
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  37. PMID 23821742
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  38. S2CID 18589882
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  39. PMID 30057174
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  40. PMID 30586752
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  41. PMID 9828430
    .

External links

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