Isobutyric acid

**Isobutyric acid**[1][2]
Skeletal formula of isobutyric acid	Ball-and-stick model of the isobutyric acid molecule
Names
	Preferred IUPAC name 2-Methylpropanoic acid[3]
	Other names Isobutyric acid; 2-Methylpropionic acid; Isobutanoic acid
Identifiers
CAS Number	79-31-2 ;
3D model (JSmol)	Interactive image;
3DMet	B00469;
ChEBI	CHEBI:16135 ;
ChEMBL	ChEMBL108778 ;
ChemSpider	6341 ;
DrugBank	DB02531 ;
ECHA InfoCard	100.001.087
EC Number	201-195-7;
IUPHAR/BPS	1060;
KEGG	C02632 ;
PubChem CID	6590;
RTECS number	NQ4375000;
UNII	8LL210O1U0 ;
UN number	2529
CompTox Dashboard (EPA)	DTXSID4021636 ;
	InChI InChI=1S/C4H8O2/c1-3(2)4(5)6/h3H,1-2H3,(H,5,6) Key: KQNPFQTWMSNSAP-UHFFFAOYSA-N ; InChI=1/C4H8O2/c1-3(2)4(5)6/h3H,1-2H3,(H,5,6) Key: KQNPFQTWMSNSAP-UHFFFAOYAB;
	SMILES O=C(O)C(C)C;
Properties
Chemical formula	C4H8O2
Molar mass	88.11 g/mol
Density	0.9697 g/cm3 (0 °C)
Melting point	−47 °C (−53 °F; 226 K)
Boiling point	155 °C (311 °F; 428 K)
Acidity (pKa)	4.86[4]
Magnetic susceptibility (χ)	-56.06x10−6 cm3/mol
Hazards
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H226, H301, H311, H314, H318, H335, H402, H412
GHS precautionary statements	P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P301+310, P301+330+331, P302+352, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P322, P330, P361
NFPA 704 (fire diamond)	2 1 0
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Isobutyric acid, also known as 2-methylpropanoic acid, is a carboxylic acid with structural formula (CH₃)₂CHCOOH. It is a colorless liquid with a somewhat unpleasant odor. It is soluble in water and organic solvents. Isobutyric acid is an isomer of n-butyric acid. Deprotonation or esterification of isobutyric acid gives derivatives called isobutyrates. Isobutyric acid is found in the free state in carobs (Ceratonia siliqua), in vanilla, and in the root of Arnica dulcis, and as an ethyl ester in croton oil.[5]

Production

Isobutyric acid is prepared by the oxidation of isobutyraldehyde, which is a byproduct of the hydroformylation of propylene.[6]

It can also be prepared by the high pressure hydrocarboxylation (Koch reaction) from propylene:[6]

CH₃CH=CH₂ + CO + H₂O → (CH₃)₂CHCO₂H

Niche methods

Many routes are known including the hydrolysis of isobutyronitrile with alkalis and the oxidation of isobutanol with potassium dichromate in the presence of sulfuric acid,[7] In the presence of proton donors, the action of sodium amalgam on methacrylic acid also gives isobutyric acid.[5]

Isobutyric acid can also be manufactured commercially using engineered bacteria using a sugar feedstock.[8]

Reactions

When heated with a chromic acid solution it is oxidized to acetone. Alkaline potassium permanganate oxidizes it[5] to α-hydroxyisobutyric acid, (CH₃)₂C(OH)-CO₂H.

Isobutyric acid is a retained trivial name under the IUPAC rules.[9]

References

Merck Index, 11th Edition, 5039
"Archived copy". Archived from the original on 2015-02-17. Retrieved 2015-03-13.CS1 maint: archived copy as title (link)
"Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 748. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
Bjerrum, J.; et al. (1958). Stability Constants. London: Chemical Society.
Chisholm, Hugh, ed. (1911). "Butyric Acid" . Encyclopædia Britannica. 4 (11th ed.). Cambridge University Press. p. 892.
Riemenschneider, Wilhelm; Bolt, Hermann (2000). Esters, Organic. Ullmann's Encyclopedia of Industrial Chemistry. p. 10. doi:10.1002/14356007.a09_565. ISBN 978-3527306732.
I. Pierre and E. Puchot (1873). "New Studies on Valerianic Acid and its Preparation on a Large Scale". Ann. Chim. Phys. 28: 366.
"Biological pathways to produce methacrylate". Archived from the original on 2012-05-02. Retrieved 2011-10-07.
Panico R, Powell WH, Richer JC, eds. (1993). "Recommendation R-9.1". A Guide to IUPAC Nomenclature of Organic Compounds. IUPAC/Blackwell Science. ISBN 0-632-03488-2.

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[1] Merck Index, 11th Edition, 5039

[2] "Archived copy". Archived from the original on 2015-02-17. Retrieved 2015-03-13.CS1 maint: archived copy as title (link)

[iupac2013-3] "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 748. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.

[4] Bjerrum, J.; et al. (1958). Stability Constants. London: Chemical Society.

[EB1911-5] Chisholm, Hugh, ed. (1911). "Butyric Acid" . Encyclopædia Britannica. 4 (11th ed.). Cambridge University Press. p. 892.

[Ullmann-6] Riemenschneider, Wilhelm; Bolt, Hermann (2000). Esters, Organic. Ullmann's Encyclopedia of Industrial Chemistry. p. 10. doi:10.1002/14356007.a09_565. ISBN 978-3527306732.

[7] I. Pierre and E. Puchot (1873). "New Studies on Valerianic Acid and its Preparation on a Large Scale". Ann. Chim. Phys. 28: 366.

[8] "Biological pathways to produce methacrylate". Archived from the original on 2012-05-02. Retrieved 2011-10-07.

[IUPAC2993-9] Panico R, Powell WH, Richer JC, eds. (1993). "Recommendation R-9.1". A Guide to IUPAC Nomenclature of Organic Compounds. IUPAC/Blackwell Science. ISBN 0-632-03488-2.