Ethanolamine (2-aminoethanol, monoethanolamine, ETA, or MEA) is an organic chemical compound with the formula HOCH2CH2NH2 (C2H7NO). The molecule is bifunctional, containing both a primary amine and a primary alcohol. Ethanolamine is a colorless, viscous liquid with an odor reminiscent of ammonia. Its derivatives are widespread in nature; e.g., lipids, as precursor of a variety of N-acylethanolamines (NAEs), that modulate several animal and plant physiological processes such as seed germination, plant–pathogen interactions, chloroplast development and flowering, as well as precursor, combined with arachidonic acid (C20H32O2; 20:4, ω-6), to form the endocannabinoid Anandamide (AEA: C22H37NO2; 20:4, ω-6).
|Preferred IUPAC name|
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||61.084 g·mol−1|
|Odor||Unpleasant ammonia-like odour|
|Melting point||10.3 °C (50.5 °F; 283.4 K)|
|Boiling point||170 °C (338 °F; 443 K)|
|Vapor pressure||64 Pa (20 °C)|
Refractive index (nD)
|1.4539 (20 °C)|
|Safety data sheet||Sigma|
|GHS Signal word||Danger|
|H302, H312, H332, H314, H335, H412|
|P261, P273, P305+351+338, P303+361+353|
|NFPA 704 (fire diamond)|
|Flash point||85 °C (185 °F; 358 K) (closed cup)|
|410 °C (770 °F; 683 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|NIOSH (US health exposure limits):|
|TWA: 3 ppm (6 mg/m3)|
IDLH (Immediate danger)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
The ethanolamines comprise a group of amino alcohols. A class of antihistamines is identified as ethanolamines, which includes carbinoxamine, clemastine, dimenhydrinate, Chlorphenoxamine, diphenhydramine and doxylamine.
Monoethanolamine is produced by treating ethylene oxide with aqueous ammonia; the reaction also produces diethanolamine and triethanolamine. The ratio of the products can be controlled by the stoichiometry of the reactants.
- 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.
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, and chemical intermediates.
Gas stream scrubbing
Like other amines, monoethanolamine is a weak base and this property is exploited in its use in gas scrubbing. Monoethanolamines can scrub combusted coal, combusted methane and combusted biogas flue emissions of carbon dioxide (CO2) very efficiently. Monoethanolamine scrubbing reduces climate change and can make historical coal and biogas industry more modern, healthier and more marketable. Legally, it is especially relevant to the Paris Agreement. MEA carbon dioxide scrubbing is also used to regenerate the air on submarines.
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 hydrogen sulfide (H2S) from various gas streams; e.g., flue gas and sour natural gas.. The MEA ionizes dissolved acidic compounds, making them polar and considerably more soluble.
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.
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).
- 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’.
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