2-Ethylhexanol (abbreviated 2-EH) is a branched, eight-carbon chiral alcohol. It is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. It is produced on a massive 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 natural plant fragrances, and the odor has been reported as "heavy, earthy, and slightly floral" for the R enantiomer and "a light, sweet floral fragrance" for the S enantiomer.
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||130.231 g·mol−1|
|Density||833 mg mL−1|
|Melting point||−76 °C (−105 °F; 197 K)|
|Boiling point||180 to 186 °C; 356 to 367 °F; 453 to 459 K|
|Vapor pressure||30 Pa (at 20 °C)|
Refractive index (nD)
Heat capacity (C)
|317.5J K−1 mol−1|
|347.0 J K−1 mol−1|
Std enthalpy of
|−433.67–−432.09 kJ mol−1|
Std enthalpy of
|−5.28857–−5.28699 MJ mol−1|
|GHS signal word||DANGER|
|H312, H315, H318, H335|
|P261, P280, P305+351+338|
|Flash point||81 °C (178 °F; 354 K)|
|290 °C (554 °F; 563 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|US health exposure limits (NIOSH):|
|TWA 50 ppm (270 mg/m3) [skin]|
IDLH (Immediate danger)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Properties and applicationsEdit
The branching in 2-ethylhexanol inhibits its crystallization due to packing disruption; this results in a very low freezing point. Esters of 2-ethylhexanol are similarly affected and it therefore finds application as a feedstock in the production of plasticizers and lubricants, where its presence helps reduce viscosity and lower freezing points.
Almost all 2-ethylhexanol manufactured is used as a precursor for the synthesis of the diester bis(2-ethylhexyl) phthalate (DEHP), a plasticizer. Because it is a fatty alcohol, its esters tend to have emollient properties.
It is also commonly used as a low volatility solvent. 2-Ethylhexanol can also be used as a cetane number booster when reacted with nitric acid. It also used to react with epichlorohydrin and sodium hydroxide to produce the glycidyl ether of the molecule which is used as an epoxy reactive diluent in various coatings, adhesives and sealants applications.
2-Ethylhexanol is produced industrially by the aldol condensation of n-butyraldehyde, followed by hydrogenation of the resulting hydroxyaldehyde. About 2,500,000 tons are prepared in this way annually.
The n-butyraldeheyde is made by hydroformylation of propylene, 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.
Although isooctanol (and the derived isooctyl prefix) is commonly used in industry to refer to 2-ethylhexanol and its derivatives, IUPAC naming conventions dictate that this name is properly applied to another isomer of octanol, 6-methylheptan-1-ol. The Chemical Abstracts Service likewise indexes isooctanol (CAS# 26952-21-6) as 6-methylheptan-1-ol.
- "2-ethylhexanol - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2005. Identification and Related Records. Retrieved 29 January 2012.
- NIOSH Pocket Guide to Chemical Hazards. "#0354". National Institute for Occupational Safety and Health (NIOSH).
- Helmut Bahrmann, Heinz-Dieter Hahn, Dieter Mayer (2005). "2-Ethylhexanol". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a10_137. ISBN 978-3527306732.CS1 maint: uses authors parameter (link)
- Klaus Rettinger; Christian Burschka; Peter Scheeben; Heike Fuchs; Armin Mosandl (1991). "Chiral 2-alkylbranched acids, esters and alcohols. Preparation and stereospecific flavour evaluation" (PDF). Tetrahedron: Asymmetry. 2 (10): 965–968. doi:10.1016/S0957-4166(00)86137-6.
- C. Kohlpaintner, M. Schulte, J. Falbe, P. Lappe, J. Weber (2008). "Aldehydes, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_321.pub2. ISBN 978-3527306732.CS1 maint: uses authors parameter (link)
- Ashford’s Dictionary of Industrial Chemicals, Third edition, 2011, page 4180-4181.
- Miller, Robert; Bennett, George (January 1961). "Producing 2-Ethylhexanol by the Guerbet Reaction". Industrial & Engineering Chemistry. 53 (1): 33–36. doi:10.1021/ie50613a027.
- IUPAC Blue Book, A2.25