2-Ethylhexanoic acid

2-Ethylhexanoic acid
Names
	Preferred IUPAC name 2-Ethylhexanoic acid
Identifiers
CAS Number	149-57-5 ; 72377-05-0 S enantiomer ; 56006-48-5 R enantiomer ;
3D model (JSmol)	Interactive image;
Beilstein Reference	1750468
ChEMBL	ChEMBL1162485 ; ChEMBL1162487 ; ChEMBL1162486 ;
ChemSpider	8373 ; 70431 R ; 119200 S ;
ECHA InfoCard	100.005.222
EC Number	205-743-6;
MeSH	2-ethylhexanoic+acid
PubChem CID	8697; 78052 R; 135309 S;
RTECS number	MO7700000;
UNII	01MU2J7VVZ ;
CompTox Dashboard (EPA)	DTXSID9025293 ;
	InChI InChI=1S/C8H16O2/c1-3-5-6-7(4-2)8(9)10/h7H,3-6H2,1-2H3,(H,9,10) Key: OBETXYAYXDNJHR-UHFFFAOYSA-N ;
	SMILES CCCCC(CC)C(O)=O;
Properties
Chemical formula	C8H16O2
Molar mass	144.214 g·mol−1
Appearance	Colorless liquid
Density	903 mg mL−1
Melting point	−59.00 °C; −74.20 °F; 214.15 K
Boiling point	228.1 °C; 442.5 °F; 501.2 K
log P	2.579
Vapor pressure	<1 Pa (at 25 °C)
Acidity (pKa)	4.819
Basicity (pKb)	9.178
Refractive index (nD)	1.425
Thermochemistry
Std enthalpy of; formation (ΔfH⦵298)	−635.1 kJ mol−1
Std enthalpy of; combustion (ΔcH⦵298)	-4.8013–4.7979 MJ mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H312, H318, H361
Precautionary statements	P280, P305+P351+P338
Flash point	114 °C (237 °F; 387 K)
Autoignition; temperature	371 °C (700 °F; 644 K)
Explosive limits	0.9–6.7%
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	1.142 g kg−1 (dermal, rabit); 3 g kg−1 (oral, rat);
Related compounds
Related compounds	2-Methylhexane; 3-Methylhexane; Valnoctamide; 2-Methylheptane; 3-Methylheptane; 2-Ethylhexanol; Valproic acid; Propylheptyl alcohol;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

2-Ethylhexanoic acid (2-EHA), commonly known as octoic acid,^[2] is the organic compound with the formula CH₃(CH₂)₃CH(C₂H₅)CO₂H. It is a carboxylic acid that is widely used to prepare lipophilic metal derivatives that are soluble in nonpolar organic solvents. 2-Ethylhexanoic acid is a colorless viscous oil. It is supplied as a racemic mixture.

Production

2-Ethylhexanoic acid is produced industrially from propylene, which is hydroformylated to give butyraldehyde. Aldol condensation of the aldehyde gives 2-ethylhexenal, which is hydrogenated to give 2-ethylhexanal. Oxidation of this aldehyde gives the carboxylic acid.^[3]

Metal ethylhexanoates

65% Solution of cobalt(II) bis(2-ethylhexanoate) in mineral spirits, tilted vial to illustrate color and viscosity.

2-Ethylhexanoic acid forms compounds with metal cations that have stoichiometry as metal acetates. These ethylhexanoate complexes are used in organic and industrial chemical synthesis.^[4] They function as catalysts in polymerizations as well as for oxidation reactions as "oil drying agents."^[5] They are highly soluble in nonpolar solvents. These metal complexes are often described as salts. They are, however, not ionic but charge-neutral coordination complexes. Their structures are akin to the corresponding acetates.

Examples of metal ethylhexanoates

Hydroxyl aluminium bis(2-ethylhexanoate), used as a thickener
Tin(II) ethylhexanoate (CAS# 301-10-0), a catalyst for polylactide and poly(lactic-co-glycolic acid).^[6]
Cobalt(II) ethylhexanoate (CAS# 136-52-7), a drier for alkyd resins
Nickel(II) ethylhexanoate (CAS# 4454-16-4)^[7]

Regulations

2-Ethylhexanoic acid is banned in the EU for use in cosmetics.^[8]

References

^ "2-ethylhexanoic acid - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 21 February 2012.
^ Economic Impact Analysis of Proposed Test Rule for 2-ethylhexanoic Acid (final) (epa Contract No. 68-01-6630) (Report). Environmental Protection Agency, Washington, DC. Office of Toxic. 2000.
^ Riemenschneider, Wilhelm (2002). "Carboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_235. ISBN 978-3527306732.
^ Mishra, Shashank; Daniele, Stéphane; Hubert-Pfalzgraf, Liliane G. (2007). "Metal 2-Ethylhexanoates and Related Compounds as Useful Precursors in Materials Science". Chemical Society Reviews. 36 (11): 1770–1787. doi:10.1039/B614334M. PMID 18213985.
^ Raju, Ravinder; Prasad, Kapa (2012). "Synthetic applications of 2-ethylhexanoic acid derived reagents". Tetrahedron. 68 (5): 1341–1349. doi:10.1016/j.tet.2011.10.078.
^ Coulembier, O.; Degee, P.; Hedrick, J. L.; Dubois, P. (2006). "Controlled Ring-Opening Polymerization to Biodegradable Aliphatic Polyester: Especially Poly(Β-Malic Acid) Derivatives". Prog. Polym. Sci. 31: 723–747. doi:10.1016/j.progpolymsci.2006.08.004.
^ Burrows, Cynthia J.; Wey, Shiow-Jyi (2001). "Nickel(II) 2-Ethylhexanoate". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn014m. ISBN 0-471-93623-5.
^ Commission Regulation (EU) 2023/1490 of 19 July 2023 amending Regulation (EC) No 1223/2009 of the European Parliament and of the Council as regards the use in cosmetic products of certain substances classified as carcinogenic, mutagenic or toxic for reproduction

[1] "2-ethylhexanoic acid - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 21 February 2012.

[2] Economic Impact Analysis of Proposed Test Rule for 2-ethylhexanoic Acid (final) (epa Contract No. 68-01-6630) (Report). Environmental Protection Agency, Washington, DC. Office of Toxic. 2000.

[3] Riemenschneider, Wilhelm (2002). "Carboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_235. ISBN 978-3527306732.

[4] Mishra, Shashank; Daniele, Stéphane; Hubert-Pfalzgraf, Liliane G. (2007). "Metal 2-Ethylhexanoates and Related Compounds as Useful Precursors in Materials Science". Chemical Society Reviews. 36 (11): 1770–1787. doi:10.1039/B614334M. PMID 18213985.

[5] Raju, Ravinder; Prasad, Kapa (2012). "Synthetic applications of 2-ethylhexanoic acid derived reagents". Tetrahedron. 68 (5): 1341–1349. doi:10.1016/j.tet.2011.10.078.

[6] Coulembier, O.; Degee, P.; Hedrick, J. L.; Dubois, P. (2006). "Controlled Ring-Opening Polymerization to Biodegradable Aliphatic Polyester: Especially Poly(Β-Malic Acid) Derivatives". Prog. Polym. Sci. 31: 723–747. doi:10.1016/j.progpolymsci.2006.08.004.

[7] Burrows, Cynthia J.; Wey, Shiow-Jyi (2001). "Nickel(II) 2-Ethylhexanoate". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn014m. ISBN 0-471-93623-5.

[8] Commission Regulation (EU) 2023/1490 of 19 July 2023 amending Regulation (EC) No 1223/2009 of the European Parliament and of the Council as regards the use in cosmetic products of certain substances classified as carcinogenic, mutagenic or toxic for reproduction

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