Pelargonic acid

Pelargonic acid, also called nonanoic acid, is an organic compound with structural formula CH₃(CH₂)₇CO₂H. It is a nine-carbon fatty acid. Nonanoic acid is a colorless oily liquid with an unpleasant, rancid odor. It is nearly insoluble in water, but very soluble in organic solvents. The esters and salts of pelargonic acid are called pelargonates or nonanoates.

Pelargonic acid

Names
Preferred IUPAC name Nonanoic acid
Other names Nonoic acid; nonylic acid; 1-octanecarboxylic acid; C9:0 (lipid numbers)
Identifiers
CAS Number	112-05-0 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1752351
ChEBI	CHEBI:29019 Y
ChEMBL	ChEMBL108436
ChemSpider	7866 Y
ECHA InfoCard	100.003.574
EC Number	203-931-2
Gmelin Reference	185341
KEGG	C01601 Y
PubChem CID	8158
UNII	97SEH7577T Y
CompTox Dashboard (EPA)	DTXSID3021641
InChI InChI=1S/C9H18O2/c1-2-3-4-5-6-7-8-9(10)11/h2-8H2,1H3,(H,10,11) Y Key: FBUKVWPVBMHYJY-UHFFFAOYSA-N Y InChI=1/C9H18O2/c1-2-3-4-5-6-7-8-9(10)11/h2-8H2,1H3,(H,10,11) Key: FBUKVWPVBMHYJY-UHFFFAOYAF
SMILES CCCCCCCCC(=O)O
Properties
Chemical formula	C9H18O2
Molar mass	158.241 g/mol
Appearance	Clear to yellowish oily liquid
Density	0.900 g/cm3
Melting point	12.5 °C (54.5 °F; 285.6 K)
Boiling point	254 °C (489 °F; 527 K)
Critical point (T, P)	439 °C (712 K), 2.35 MPa
Solubility in water	0.3 g/L
Acidity (pKa)	4.96[1] 1.055 at 2.06–2.63 K (−271.09 – −270.52 °C; −455.96 – −454.94 °F) 1.53 at −191 °C (−311.8 °F; 82.1 K)
Refractive index (nD)	1.4322
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Corrosive
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H412
Precautionary statements	P264, P273, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, P362, P501
NFPA 704 (fire diamond)	3 1 0
Flash point	114 °C (237 °F; 387 K)
Autoignition temperature	405 °C (761 °F; 678 K)
Related compounds
Related compounds	Octanoic acid, decanoic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The acid is named after the pelargonium plant, since oil from its leaves contains esters of the acid.

Preparation

Together with azelaic acid, it is produced industrially by ozonolysis of oleic acid.^[2]

CH₃(CH₂)₇CH=CH(CH₂)₇CO₂H + O₃ → CH₃(CH₂)₇CO₂H + HO₂C(CH₂)₇CO₂H

Alternatively, pelargonic acid can be produced in a two-step process beginning with coupled dimerization and hydroesterification of 1,3-butadiene. This step produces a doubly unsaturated C9-ester, which can be hydrogenated to give esters of pelargonic acid.^[3]

2 CH₂=CHCH=CH₂ + CO + CH₃OH → CH₂=CH(CH₂)₃CH=CHCH₂CO₂CH₃

CH₂=CH(CH₂)₃CH=CHCH₂CO₂CH₃ + 2 H₂ → CH₃(CH₂)₇CO₂CH₃

A laboratory preparation involves permanganate oxidation of 1-decene.^[4]

Occurrence and uses

Pelargonic acid occurs naturally as esters in the oil of Pelargonium.

Synthetic esters of pelargonic acid, such as methyl pelargonate, are used as flavorings. Pelargonic acid is also used in the preparation of plasticizers and lacquers. The derivative 4-nonanoylmorpholine is an ingredient in some pepper sprays.

The ammonium salt of pelargonic acid, ammonium pelargonate, is a herbicide. It is commonly used in conjunction with glyphosate, a non-selective herbicide, for a quick burn-down effect in the control of weeds in turfgrass. It works by causing leaks in plant cell membranes, allowing chlorophyll molecules to escape the chloroplast. Under sunlight, these misplaced molecules cause immense oxidative damage to the plant.^[5]

The methyl form and ethylene glycol pelargonate act as nematicides against Meloidogyne javanica on Solanum lycopersicum, and the methyl against Heterodera glycines and M. incognita on Glycine max.^[6]

Esters of pelargonic acid are precursors to lubricants.

Pharmacological effects

Pelargonic acid may be more potent than valproic acid in treating seizures.^[7] Moreover, in contrast to valproic acid, pelargonic acid exhibited no effect on HDAC inhibition, suggesting that it is unlikely to show HDAC inhibition-related teratogenicity.^[7]

See also

• List of saturated fatty acids
• List of carboxylic acids