Ethanolamine

Ethanolamine
Names
Preferred IUPAC name
2-Aminoethan-1-ol[1]
Other names
2-Aminoethanol
2-Amino-1-ethanol
Ethanolamine (not recommended[1])
Monoethanolamine
β-Aminoethanol
β-hydroxyethylamine
β-Aminoethyl alcohol
Glycinol
Olamine
MEA
Ethylolamine
2-Hydroxyethylamine
Identifiers
141-43-5 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:16000 YesY
ChEMBL ChEMBL104943 YesY
ChemSpider 13835336 YesY
DrugBank DB03994 YesY
ECHA InfoCard 100.004.986
EC Number 205-483-3
KEGG D05074 YesY
PubChem 700
RTECS number KJ5775000
UNII 5KV86114PT YesY
Properties
C2H7NO
Molar mass 61.08 g·mol−1
Appearance Viscous colourless liquid
Odor unpleasant ammonia-like odour
Density 1.012 g/cm3
Melting point 10.3 °C (50.5 °F; 283.4 K)
Boiling point 170 °C (338 °F; 443 K)
Miscible
Vapor pressure 64 Pa (20 °C)[2]
Acidity (pKa) 9.50[3]
1.4539 (20 °C)[4]
Hazards
Safety data sheet JT Baker
R-phrases R20, R34, R36/37/38
S-phrases S26, S27, S36/37, S39, S45
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
2
3
0
Flash point 85 °C (185 °F; 358 K) (closed cup)
410 °C (770 °F; 683 K)
Explosive limits 5.5 - 17%
Lethal dose or concentration (LD, LC):
3320 mg/kg (rat, oral)
620 mg/kg (guinea pig, oral)
2050 mg/kg (rat, oral)
1475 mg/kg (mouse, oral)
1000 mg/kg (rabbit, oral)
700 mg/kg (mouse, oral)
1720-1970 mg/kg (rat, oral)[5]
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 3 ppm (6 mg/m3)[6]
REL (Recommended)
 TWA 3 ppm (8 mg/m3) ST 6 ppm (15 mg/m3)[6]
IDLH (Immediate danger)
 30 ppm[6]
Related compounds
Related compounds
 N-Methylethanolamine
diethanolamine
triethanolamine
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

Ethanolamine, also called 2-aminoethanol or monoethanolamine (often abbreviated as ETA or MEA), is an organic chemical compound with the formula HOCH2CH2NH2. The molecule is both a primary amine and a primary alcohol (due to a hydroxyl group). Ethanolamine is a colorless, viscous liquid with an odor reminiscent to that of ammonia. Its derivatives are widespread in nature, e.g., lipids.

The ethanolamines comprise a group of amino alcohols. A class of antihistamines is identified as ethanolamines, which includes carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, and doxylamine.[7]

Industrial production

Monoethanolamine is produced by reacting ethylene oxide with aqueous ammonia; the reaction also produces diethanolamine and triethanolamine. The ratio of the products can be controlled by changing the stoichiometry of the reactants.[8]

Note that this reaction is exothermic and that controls are needed to prevent a runaway reaction.

Biochemistry

Ethanolamine is biosynthesized by decarboxylation of serine:[9]

HOCH2CH(CO2H)NH2 → HOCH2CH2NH2 + CO2

Ethanolamine is the second-most-abundant head group for phospholipids, substances found in biological membranes (particularly those of prokaryotes), e.g., phosphatidylethanolamine. It is also used in messenger molecules such as palmitoylethanolamide, which has an effect on CB1 receptors.[10]

Applications

Ethanolamine is commonly called monoethanolamine or MEA in order to be distinguished from diethanolamine (DEA) and triethanolamine (TEA). It is used as feedstock in the production of detergents, emulsifiers, polishes, pharmaceuticals, corrosion inhibitors, chemical intermediates.

Gas stream scrubbing

Like other amines, monoethanolamine is a weak base and this property is exploited in its use in gas scrubbing.

Aqueous solutions of MEA (solutions of MEA in water) are used as a gas stream scrubbing liquid in amine treaters. For example, aqueous MEA is used to remove carbon dioxide (CO2) and H2S from various gas streams, e.g., flue gas and sour natural gas.[11] The MEA reacts with acidic compounds dissolved in the solution, turning the molecules into an ionic form, making them polar and considerably more soluble in a cold MEA solution, and thus keeping such acidic gases dissolved in this gas-scrubbing solution. Therefore, large surface area contact with such a cold scrubbing solution in a scrubber unit can selectively remove such acidic components as hydrogen sulfide (H2S) and CO2 from some mixed gas streams. For example, basic solutions such as aqueous MEA or aqueous potassium carbonate can neutralize H2S into hydrosulfide ion (HS−) or CO2 into bicarbonate ion (HCO3−).

In contrast to MEO, strong bases such as sodium hydroxide (NaOH) will not readily release these gases once they have dissolved. However, MEA, being rather weak base, will re-release H2S or CO2 when the scrubbing solution is heated. Therefore, the MEA scrubbing solution is recycled through a regeneration unit, which heats the MEA solution from the scrubber unit to release these only slightly acidic gases into a purer form and returns the regenerated MEA solution to the scrubber unit again for reuse.[8][12] For example, reacting ethanolamine with ammonia gives ethylenediamine, a precursor of the commonly used chelating agent, EDTA :[8]

Other uses

In pharmaceutical formulations, MEA is used primarily for buffering or preparation of emulsions. MEA can be used as pH regulator in cosmetics.[13]

It is also an injectable sclerosant as a treatment option of symptomatic hemorrhoids. 2-5 ml of ethanolamine oleate can be injected into the mucosa just above the hemorrhoids to cause ulceration and mucosal fixation thus preventing hemorrhoids from descending out of the anal canal.

pH-control amine

Ethanolamine is often used for alkalinization of water in steam cycles of power plants, including nuclear power plants with pressurized water reactors. This alkalinization is performed to control corrosion of metal components. ETA (or sometimes a similar organic amine, e.g., morpholine) is selected because it does not accumulate in steam generators (boilers) and crevices due to its volatility, but rather distributes relatively uniformly throughout the entire steam cycle. In such application, ETA is a key ingredient of so-called "all-volatile treatment" of water (AVT).

References

  1. 1 2 Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 649, 717. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4. For example, the name ‘ethanolamine’, which is still widely used, is badly constructed because of the presence of two suffixes; it is not an alternative to the preferred IUPAC name, ‘2-aminoethan-1-ol’.
  2. ↑ "Ethanolamine MSDS" (PDF). Acros Organics.
  3. ↑ Hall, H.K., J. Am. Chem. Soc., 1957, 79, 5441.
  4. ↑ R. E. Reitmeier; V. Sivertz; H. V. Tartar (1940). "Some Properties of Monoethanolamine and its Aqueous Solutions". Journal of the American Chemical Society. 62 (8): 1943–1944. doi:10.1021/ja01865a009.
  5. ↑ "Ethanolamine". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
  6. 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0256". National Institute for Occupational Safety and Health (NIOSH).
  7. ↑ Cough, Cold, and Allergy Preparation Toxicity at eMedicine
  8. 1 2 3 Klaus Weissermel; Hans-Jürgen Arpe; Charlet R. Lindley; Stephen Hawkins (2003). "Chap. 7. Oxidation Products of Ethylene". Industrial Organic Chemistry. Wiley-VCH. pp. 159–161. ISBN 3-527-30578-5.
  9. ↑ http://lipidlibrary.aocs.org/Lipids/pe/index.htm
  10. ↑ Calignano, A; La Rana, G; Piomelli, D (2001). "Antinociceptive activity of the endogenous fatty acid amide, palmitylethanolamide". European Journal of Pharmacology. 419 (2–3): 191–8. doi:10.1016/S0014-2999(01)00988-8. PMID 11426841.
  11. ↑ http://www.nap.edu/openbook.php?record_id=11170[]
  12. ↑ "Ethanolamine". Occupational Safety & Health Administration.
  13. ↑ Carrasco, F. (2009). "Ingredientes Cosméticos". Diccionario de Ingredientes Cosméticos 4ª Ed. www.imagenpersonal.net. p. 306. ISBN 978-84-613-4979-1.
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