2-Ethylhexanol (abbreviated 2-EH) is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
with formula CHO. It is a branched, eight-carbon
chiral alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
. It is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. It is
produce
Produce is a generalized term for many farm-produced crops, including fruits and vegetables ( grains, oats, etc. are also sometimes considered ''produce''). More specifically, the term ''produce'' often implies that the products are fres ...
d on a large scale (>2,000,000,000 kg/y) for use in numerous applications such as solvents, flavors, and fragrances and especially as a precursor for production of other chemicals such as emollients and plasticizers.
[ It is encountered in plants, fruits, and wines. The odor has been reported as "heavy, earthy, and slightly floral" for the R ]enantiomer
In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical anti ...
and "a light, sweet floral fragrance" for the S enantiomer.
Properties and applications
The branching in 2-ethylhexanol inhibits crystallization. Esters of 2-ethylhexanol are similarly affected, which together with low volatility, is the basis of applications in the production of plasticizer
A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture.
Plasticiz ...
s and lubricants, where its presence helps reduce viscosity and lower freezing points. Because 2-ethylhexanol is a fatty alcohol
Fatty alcohols (or long-chain alcohols) are usually high-molecular-weight, straight-chain primary alcohols, but can also range from as few as 4–6 carbons to as many as 22–26, derived from natural fats and oils. The precise chain length varies ...
, its ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...
s have emollient
A moisturizer, or emollient, is a cosmetic preparation used for protecting, moisturizing, and lubricating the skin. These functions are normally performed by sebum produced by healthy skin. The word "emollient" is derived from the Latin verb ''m ...
properties. Representative is the diester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are ...
bis(2-ethylhexyl) phthalate
Bis(2-ethylhexyl) phthalate (di-2-ethylhexyl phthalate, diethylhexyl phthalate, diisooctyl phthalate, DEHP; incorrectly — dioctyl phthalate, DIOP) is an organic compound with the formula C6H4(CO2C8H17)2. DEHP is the most common member of the cl ...
(DEHP), commonly used in PVC. The triester tris (2-Ethylhexyl) trimellitate (TOTM) is another common plasticizer produced via the esterification
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...
of three 2-ethylhexanol per trimellitic acid.
It is also commonly used as a low volatility solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
. 2-Ethylhexanol can also be used as a cetane improver when reacted with nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...
. It also used to react with epichlorohydrin
Epichlorohydrin (abbreviated ECH) is an organochlorine compound and an epoxide. Despite its name, it is not a halohydrin. It is a colorless liquid with a pungent, garlic-like odor, moderately soluble in water, but miscible with most polar organ ...
and sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and al ...
to produce the glycidyl ether of the molecule which is used as an epoxy reactive diluent in various coating
A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. Pow ...
s, adhesive
Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation.
The use of adhesives offers certain advant ...
s and sealant
Sealant is a substance used to block the passage of fluids through openings in materials, a type of mechanical seal. In building construction ''sealant'' is sometimes synonymous with '' caulking'' and also serve the purposes of blocking dust, so ...
s applications. It can be used in the development of photos, production of rubber and extraction of oil and gas.
Industrial production
2-Ethylhexanol is produced industrially by the aldol condensation of ''n''-butyraldehyde
Butyraldehyde, also known as butanal, is an organic compound with the formula CH3(CH2)2CHO. This compound is the aldehyde derivative of butane. It is a colorless flammable liquid with an unpleasant smell. It is miscible with most organic solvent ...
, followed by hydrogenation of the resulting hydroxyaldehyde. About 2,500,000 tons are prepared in this way annually.
The ''n''-butyraldehyde is made by hydroformylation
Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon ...
of propylene
Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petro ...
, either in a self-contained plant or as the first step in a fully integrated facility. Most facilities make ''n''-butanol and isobutanol in addition to 2-ethylhexanol. Alcohols prepared in this way are sometimes referred to as oxo alcohols. The overall process is very similar to that of the Guerbet reaction, by which it may also be produced.
Health effects
2-Ethylhexanol exhibits low toxicity in animal models, with LD50 ranging from 2-3 g/kg (rat). 2-Ethylhexanol has been identified as a cause of indoor air quality
Indoor air quality (IAQ) is the air quality within and around buildings and structures. IAQ is known to affect the health, comfort, and well-being of building occupants. Poor indoor air quality has been linked to sick building syndrome, reduce ...
related health problems, such as respiratory system
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies g ...
irritation, as a volatile organic compound
Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a ...
. 2-Ethylhexanol is emitted to air from a PVC flooring installed on concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
that had not been dried properly.
2-Ethylhexanol has been linked to developmental toxicity
Development of the human body is the process of growth to maturity. The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mitosi ...
(increased incidence of skeletal malformations in fetuses). This is thought to be a result of metabolism of 2-ethylhexanol into 2-ethylhexanoic acid via oxidation of the primary alcohol. The teratogenicity of 2-ethylhexanoic acid, as well as similar substances such as valproic acid, has been well established.
Nomenclature
Although isooctanol (and the derived isooctyl prefix) is commonly used in industry to refer to 2-ethylhexanol and its derivatives, IUPAC
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
naming conventions dictate that this name is properly applied to another isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Is ...
of octanol, 6-methylheptan-1-ol. The Chemical Abstracts Service
CAS (formerly Chemical Abstracts Service) is a division of the American Chemical Society. It is a source of chemical information. CAS is located in Columbus, Ohio, United States.
Print periodicals
''Chemical Abstracts'' is a periodical index th ...
likewise indexes isooctanol (CAS# 26952-21-6) as 6-methylheptan-1-ol.
See also
* 2-Ethylhexanoic acid
References
External links
Isooctyl alcohol
National Institute for Occupational Safety and Health (NIOSH)
{{DEFAULTSORT:Ethylhexanol, 2-
Alcohol solvents
Alkanols
Primary alcohols