2-Ethylhexanol

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.[3] 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.[4]

2-Ethylhexanol
Names
IUPAC name
2-Ethylhexan-1-ol[1]
Identifiers
3D model (JSmol)
1719280
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.941
EC Number
  • 203-234-3
KEGG
MeSH 2-ethylhexanol
UNII
Properties
C8H18O
Molar mass 130.231 g·mol−1
Appearance Colourless liquid
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
log P 2.721
Vapor pressure 30 Pa (at 20 °C)
1.431
Thermochemistry
317.5J K−1 mol−1
347.0 J K−1 mol−1
Std enthalpy of
formation (ΔfH⦵298)
 −433.67–−432.09 kJ mol−1
Std enthalpy of
combustion (ΔcH⦵298)
 −5.28857–−5.28699 MJ mol−1
Hazards
GHS pictograms
GHS Signal word Danger
GHS hazard statements
 H312, H315, H318, H335
P261, P280, P305+351+338
Flash point 81 °C (178 °F; 354 K)
290 °C (554 °F; 563 K)
Explosive limits 0.88–9.7%
Lethal dose or concentration (LD, LC):
  • 1.97 g kg−1 (dermal, rabbit)
  • 3.73 g kg−1 (oral, rat)
NIOSH (US health exposure limits):
PEL (Permissible)
 none[2]
REL (Recommended)
 TWA 50 ppm (270 mg/m3) [skin][2]
IDLH (Immediate danger)
 N.D.[2]
Related compounds
Related alkanol
 Propylheptyl alcohol
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Properties and applications

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.

A significant portion of 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. It can be used in the development of photos, production of rubber and extraction of oil and gas.[5]

Industrial production

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.[6][7]

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.[8]

Health effects

2-Ethylhexanol exhibits low toxicity in animal models, with LD50 ranging from 2-3 g/kg (rat).[3] 2-Ethylhexanol has been identified as a cause of indoor air quality related health problems, such as respiratory system irritation, as a volatile organic compound. 2-Ethylhexanol is emitted to air from a PVC flooring installed on concrete that had not been dried properly.[9][10]

Nomenclature

Although isooctanol (and the derived isooctyl prefix) is commonly used in industry to refer to 2-ethylhexanol and its derivatives, IUPAC naming conventions[11] 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.

See also

References
  1. "2-ethylhexanol - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2005. Identification and Related Records. Retrieved 29 January 2012.
  2. NIOSH Pocket Guide to Chemical Hazards. "#0354". National Institute for Occupational Safety and Health (NIOSH).
  3. 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)
  4. 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.
  5. https://berrymanchemical.com/blog/2-ethylhexanol/
  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)
  7. Ashford’s Dictionary of Industrial Chemicals, Third edition, 2011, page 4180-4181.
  8. Miller, Robert; Bennett, George (January 1961). "Producing 2-Ethylhexanol by the Guerbet Reaction". Industrial & Engineering Chemistry. 53 (1): 33–36. doi:10.1021/ie50613a027.
  9. Ernstgård, L.; Norbäck, D. (2010). "Acute effects of exposure to 1 mg/m(3) of vaporized 2-ethyl-1-hexanol in humans". Indoor Air. 20 (2): 168–75. doi:10.1111/j.1600-0668.2009.00638.x.
  10. Hildenbrand, S.; Wodarz, R. (2009). "Biomonitoring of the di(2-ethylhexyl) phthalate metabolites mono(2-ethyl-5-hydroxyhexyl) phthalate and mono(2-ethyl-5-oxohexyl) phthalate in children and adults during the course of time and seasons". International Journal of Hygiene and Environmental Health. 212 (6): 679–84. doi:10.1016/j.ijheh.2009.06.003.
  11. IUPAC Blue Book, A2.25
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