Ethanolamine
Ethanolamine, also known as 2-aminoethanol, monoethanolamine (MEA), or ETA, is a naturally occurring organic chemical compound with the formula HOCH2CH2NH2 or C2H7NO[1]. It is a bifunctional molecule, containing both a primary amine and a primary alcohol. Ethanolamine is a colorless, viscous liquid with an odor reminiscent of ammonia[1].
Biological Significance
Ethanolamine molecules are a component in the formation of cellular membranes and are thus a molecular building block for life. It is the second-most-abundant head group for phospholipids, substances found in biological membranes (particularly those of prokaryotes); for example, phosphatidylethanolamine. Ethanolamine is also used in messenger molecules such as palmitoylethanolamide, which has an effect on CB1 receptors. It was thought to exist only on Earth and on certain asteroids, but in 2021, evidence was found that ethanolamine molecules exist in interstellar space[3].
Industrial Production and Applications
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. MEA is used as feedstock in the production of detergents, emulsifiers, polishes, pharmaceuticals, corrosion inhibitors, and chemical intermediates. For example, reacting ethanolamine with ammonia gives ethylenediamine, a precursor of the commonly used chelating agent, EDTA. Monoethanolamines can scrub combusted-coal, combusted-methane, and combusted-biogas flue emissions of carbon dioxide (CO2) very efficiently. 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; for example, flue gas and sour natural gas. The MEA ionizes dissolved acidic compounds, making them polar and considerably more soluble. MEA scrubbing solutions can be recycled through a regeneration unit. When heated, MEA, being a rather weak base, will release dissolved H2S or CO2 gas, resulting in a pure MEA solution.
Hazard Information
Ethanolamine can affect humans when breathed in and by passing through the skin[2]. It is a corrosive chemical and contact can severely irritate and burn the skin and eyes with possible eye damage[2]. Breathing ethanolamine can irritate the nose, throat, and lungs, causing coughing, wheezing, and/or shortness of breath[2]. Ethanolamine may cause a skin allergy[2]. If an allergy develops, very low future exposure can cause itching and a skin rash[2]. Ethanolamine may damage the liver and kidneys[2]. High exposure may affect the nervous system[2]. It is on the Hazardous Substance List because it is regulated by OSHA and cited by ACGIH, DOT, NIOSH, and NFPA[2]. This chemical is on the Special Health Hazard Substance List because it is corrosive[2].
Other Uses
In pharmaceutical formulations, MEA is used primarily for buffering or preparation of emulsions. MEA can be used as a pH regulator in cosmetics. It is an injectable sclerosant as a treatment option for symptomatic hemorrhoids. 2–5 ml of ethanolamine oleate can be injected into the mucosa just above the hemorrhoids to cause ulceration and mucosal fixation. It is also an ingredient in cleaning fluid for automobile windshields. Ethanolamine is often used for alkalinization of water in steam cycles of power plants, including nuclear power plants with pressurized water reactors.
Citations:
[1] https://en.wikipedia.org/wiki/Ethanolamine
[2] https://nj.gov/health/eoh/rtkweb/documents/fs/0835.pdf
[3] https://www.acs.org/molecule-of-the-week/archive/e/ethanolamine.html
[4] https://www.ewg.org/skindeep/ingredients/702286-ETHANOLAMINE/
[5] https://www.sigmaaldrich.com/US/en/product/sial/e9508