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Hexanoic acid, 2-ethyl-, commonly known as octoic acid, is the organic compound with the formula CH3(CH2)3CH(C2H5)CO2H.
Hexanoic acid, 2-ethyl- 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.
CAS Registry Number: 149-57-5
Molecular Formula: C₈H₁₆O₂
Molecular Weight: 144.21 g/mol
Structure: An aliphatic, branched-chain monocarboxylic acid based on an 8-carbon backbone, supplied commercially as a racemic mixture
Synonyms: α-Ethylcaproic acid; α-Ethylhexanoic acid, Butylethylacetic acid, Ethylhexanoic acid, Ethylhexoic acid, 2-Butylbutanoic acid, 2-Ethylcaproic acid, 2-Ethylhexanoic acid, 2-Ethylhexoic acid, 3-Heptanecarboxylic acid, Kyselina 2-ethylkapronova, Kyselina heptan-3-karboxylova, 2-Ethyl-1-hexanoic acid, 2-Ethylcapronic acid, NSC 8881
Hexanoic acid, 2-ethyl-, also known as octoic acid, is a clear, colorless liquid carboxylic acid with the chemical formula C₈H₁₆O₂.
Hexanoic acid, 2-ethyl- is a highly valued industrial chemical intermediate, primarily used to produce lipophilic metal derivatives (metal soaps), plasticizers, synthetic lubricants, and automotive coolants.
Hexanoic acid, 2-ethyl-, commonly known as 2-Ethylhexanoic Acid (2-EHA), is a branched-chain carboxylic acid widely used as an intermediate in the chemical industry.
Hexanoic acid, 2-ethyl- is an important raw material for the production of metal salts, plasticizers, lubricants, coatings, and various specialty chemicals.
Ethylhexoic acid is a colorless to light yellow liquid with a mild odor.
Hexanoic acid, 2-ethyl- will burn though it may take some effort to ignite.
Hexanoic acid, 2-ethyl- is slightly soluble in water.
Hexanoic acid, 2-ethyl- is corrosive to metals and tissue.
Hexanoic acid, 2-ethyl- is used to make paint dryers and plasticizers.
Hexanoic acid, 2-ethyl- is a dense, clear, colorless, high boiling liquid and is the most highly produced commercial aliphatic carboxylic acid.
Hexanoic acid, 2-ethyl- is made via an oxidation of 2-ethyl-1-hexanol or 2-ethylhexanal and is of particular importance in materials science, catalysis, paint industries, and has a variety of commercial uses.
Hexanoic acid, 2-ethyl- has found widespread use in plasticizers, automotive coolants, synthetic lubricants, metal soaps, for paint driers, PVC stabilizers, wetting agent in emulsions, as a co-solvent, and defoamer in pesticides.
Hexanoic acid, 2-ethyl- is supplied as a racemic mixture.
Esters and salts of 2-EHA are called 2-ethylhexanoates, e.g. potassium 2-ethylhexanoate.
General description
Hexanoic acid, 2-ethyl- is an industrially important aliphatic carboxylic acid.
Hexanoic acid, 2-ethyl- is widely employed as a stabilizer and a wood preservative.
Hexanoic acid, 2-ethyl- has various industrial applications, such as:
coolant in automotives
synthetic lubricant
wetting agent
co-solvent
drying of paints
defoaming agent in pesticides
Production
Hexanoic acid, 2-ethyl- is produced industrially from butyraldehyde, which is obtained by hydroformylation of propylene.
Aldol condensation of the aldehyde gives 2-ethylhexenal, which is hydrogenated to give 2-ethylhexanal.
Oxidation of this aldehyde gives the carboxylic acid.
Production
Hexanoic acid, 2-ethyl- is typically manufactured through the oxidation of 2-ethylhexanol, which itself is produced from petrochemical feedstocks.
Industrial production methods are optimized to achieve high purity and consistent quality.
Metal ethylhexanoates
Salts, esters, and coordination complexes derived from 2-ethylhexanoic acid are called 2-ethylhexanoates.
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.
They function as catalysts in polymerizations as well as for oxidation reactions as "oil drying agents."
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.
Key Applications
Because Hexanoic acid, 2-ethyl- has a long hydrocarbon chain, Hexanoic acid, 2-ethyl- forms metal salts that are highly soluble in non-polar organic solvents and hydrocarbons.
Automotive: Used to manufacture corrosion inhibitors and wetting agents in automotive coolants.
Lubricants: Serves as a raw material for polyolesters used in high-performance synthetic lubricants.
Coatings & Paints: Used in the synthesis of alkyd resins to provide improved resistance to yellowing, and serves as a raw material for metal-based paint driers.
Plastics & Polymers: Utilized to create esters for PVC stabilizers and peroxides used as catalysts in polyethylene production.
Manufacturing
Industrially, Hexanoic acid, 2-ethyl- is produced via the oxidation of 2-ethyl-1-hexanol or 2-ethylhexanal.
These are typically derived from propylene through an oxo-synthesis process.
Reactivity Profile
Hexanoic acid, 2-ethyl- is a carboxylic acid.
Carboxylic acids donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic.
Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat.
Neutralization between an acid and a base produces water plus a salt.
Carboxylic acids with six or fewer carbon atoms are freely or moderately soluble in water; those with more than six carbons are slightly soluble in water.
Soluble carboxylic acid dissociate to an extent in water to yield hydrogen ions.
The pH of solutions of carboxylic acids is therefore less than 7.0.
Many insoluble carboxylic acids react rapidly with aqueous solutions containing a chemical base and dissolve as the neutralization generates a soluble salt.
Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt.
Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry.
Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in 2-Ethylhexanoic acid to corrode or dissolve iron, steel, and aluminum parts and containers.
Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide.
The reaction is slower for dry, solid carboxylic acids.
Insoluble carboxylic acids react with solutions of cyanides to cause the release of gaseous hydrogen cyanide.
Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides.
Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat.
Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat.
Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents.
These reactions generate heat. A wide variety of products is possible.
Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions.
Application
A review of the environmental fate and aquatic effects of a series of C4 and C8 oxo-process chemicals: This review assesses the environmental impact of C4 and C8 oxo-process chemicals, including 2-Ethylhexanoic acid, detailing their degradation, persistence, and effects on aquatic ecosystems
Applications
2-Ethylhexanoic acid has numerous industrial applications, including:
Metal Soaps and Metal Salts: Used to produce metal 2-ethylhexanoates such as cobalt, zinc, calcium, and manganese salts.
Paints and Coatings: Functions as a raw material for driers and additives in alkyd paints and industrial coatings.
Lubricants: Used in the manufacture of synthetic lubricants and lubricant additives.
Plasticizers: Serves as an intermediate in producing plasticizers for polymers and plastics.
Catalysts: Used in catalyst formulations for polymerization and other chemical processes.
Chemical Intermediates: Acts as a building block in the synthesis of specialty chemicals and pharmaceuticals.
Uses
2-Ethylhexanoic acid is used in the preparation of metal derivatives, which act as a catalyst in polymerization reactions.
For example, tin 2-ethylhexanoate is used in the manufacturing of poly(lactic-co-glycolic acid).
Hexanoic acid, 2-ethyl- is also used as a stabilizer for polyvinyl chlorides.
Hexanoic acid, 2-ethyl- is also involved in solvent extraction and dye granulation.
Further, Hexanoic acid, 2-ethyl- is used to prepare plasticizers, lubricants, detergents, flotation aids, corrosion inhibitors and alkyd resins.
In addition to this, Hexanoic acid, 2-ethyl- serves as a catalyst for polyurethane foaming.
2-Ethylhexanoic acid can be used:
As a reactant in esterification , decarboxylative alkynylation , and preparation of alkyl coumarins via decarboxylative coupling reactions.
In the organocatalytic medium for the preparation of various 3,4-dihydropyrimidin-2(1H)-ones/thiones by Biginelli reaction.
Paint and varnish driers (metallic salts).
Ethylhexoates of light metals are used to convert some mineral oils to greases.
Its esters are used as plasticizers.
Advantages
Excellent compatibility with organic systems
Good thermal and oxidative stability
Effective metal complexing properties
Low volatility compared to many lower molecular weight carboxylic acids
Health Hazard
Harmful if swallowed, inhaled or absorbed through skin.
Material is extremely destructive to tissues of mucous membranes and upper respiratory tract, eyes and skin.
Inhalation may be fatal as a result of spasm, inflammation and edema of the larynx, bronchii, chemical pneumonitis and pulmonary edema.
Symptoms of exposure may include burning sensation, coughing, wheezing, laryngitis, shortness of breath, headache, nausea and vomiting.
Fire Hazard
2-Ethylhexanoic acid is combustible.
Safety & Handling
Physical Properties: Hexanoic acid, 2-ethyl- is a viscous liquid with a mild odor, a boiling point of 228°C (442°F), and is generally immiscible in water.
Precautions: Users should wear appropriate Personal Protective Equipment (PPE) such as chemical-resistant gloves and safety goggles.
Hexanoic acid, 2-ethyl- can cause skin and eye irritation and should be kept out of waterways.
Properties
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
Flash point: 230 °F
storage temp.: Store below +30°C.
solubility: 1.4g/l
form: Liquid
pka: pK1:4.895 (25°C)
PH: 3 (1.4g/l, H2O, 20℃)
IUPAC Standard InChI: InChI=1S/C8H16O2/c1-3-5-6-7(4-2)8(9)10/h7H,3-6H2,1-2H3,(H,9,10)
IUPAC Standard InChIKey: OBETXYAYXDNJHR-UHFFFAOYSA-N
