2-Ethylhexanol

2-Ethylhexanol
2-Ethylhexanol molecule
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 130.23 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
−433.67–−432.09 kJ mol−1
−5.28857–−5.28699 MJ mol−1
Hazards
GHS pictograms
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)
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)
US health exposure limits (NIOSH):
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).
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Infobox references

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]

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.

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 an octane booster when reacted with nitric acid.

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.[5][6]

The n-butyraldehyde 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. The overall process is very similar to that of the Guerbet reaction, by which it may also be produced.[7]

Health effects

2-Ethylhexanol exhibits low toxicity in animal models, with LD50 ranging from 2-3 g/kg (rat).[3]

Nomenclature

Although isooctanol (and the derived isooctyl prefix) is commonly used in industry to refer to 2-ethylhexanol and its derivatives, IUPAC naming conventions[8] 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. 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0354". National Institute for Occupational Safety and Health (NIOSH).
  3. 1 2 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.
  4. ↑ Klaus Rettinger; Christian Burschka; Peter Scheeben; Heike Fuchs; Armin Mosandl (1991). "Chiral 2-alkylbranched acids, esters and alcohols. Preparation and stereospecific flavour evaluation". Tetrahedron: Asymmetry. 2 (10): 965–968. doi:10.1016/S0957-4166(00)86137-6.
  5. ↑ 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.
  6. ↑ Ashford’s Dictionary of Industrial Chemicals, Third edition, 2011, page 4180-4181.
  7. ↑ Miller, Robert; Bennett, George (January 1961). "Producing 2-Ethylhexanol by the Guerbet Reaction". Industrial & Engineering Chemistry. 53 (1): 33–36. doi:10.1021/ie50613a027.
  8. ↑ IUPAC Blue Book, A2.25
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