Product Code Database
Ethanolamine ( 2-aminoethanol, monoethanolamine, ETA, or MEA) is a naturally occurring organic chemical compound with the formula or . The molecule is bifunctional, containing both a primary amine and a primary alcohol. Ethanolamine is a , viscous liquid with an odor reminiscent of ammonia.
Ethanolamine is commonly called monoethanolamine or MEA in order to be distinguished from diethanolamine (DEA) and triethanolamine (TEOA). 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.
In 1897 Ludwig Knorr developed the modern industrial route (see below) and separated the products, including MEA, by fractional distillation, for the first time studying their properties.
None of the ethanolamines were of any commercial importance until after the WWII industrial production of ethylene oxide took off.
MEA was thought to exist only on Earth and on certain asteroids, but in 2021 evidence was found that these molecules exist in interstellar space.
Ethanolamine is biosynthesis by decarboxylation of serine:
Derivatives of ethanolamine are widespread in nature; e.g., , as precursor of a variety of N-acylethanolamines (NAEs), that modulate several animal and plant Physiology processes such as seed germination, plant–pathogen interactions, chloroplast development and Flowering plant, as well as precursor, combined with arachidonic acid 20:Double bond, ω-6), to form the endocannabinoid anandamide (AEA: ; 20:4, ω-6).
MEA is biodegraded by ethanolamine ammonia-lyase, a B12-dependent enzyme. It is converted to acetaldehyde and ammonia via initial H-atom abstraction.
For example, reacting ethanolamine with ammonia gives ethylenediamine, a precursor of the commonly used chelating agent, EDTA.
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 () and hydrogen sulfide () from various gas streams; e.g., flue gas and sour natural gas. The MEA ionizes dissolved acidic compounds, making them Polar molecule 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 or gas resulting in a pure MEA solution.
It is 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.
It is also an ingredient in cleaning fluid for automobile .
Gas stream scrubbing
Monoethanolamines can scrub combusted-coal, combusted-methane and combusted-biogas flue emissions of carbon dioxide () very efficiently. MEA carbon dioxide scrubbing is also used to regenerate the air on submarines.
Other uses
In pharmaceutical formulations, MEA is used primarily for buffering or preparation of emulsions. MEA can be used as pH regulator in cosmetics.
pH-control amine
Ethanolamine is often used for alkalinization of water in steam cycles of power plants, including nuclear 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).
Reactions
Upon reaction with carbon dioxide, 2 equivalents of ethanolamine react through the intermediacy of carbonic acid to form a carbamate salt, which when heated usually reforms back to ethanolamine and carbon dioxide but occasionally can also cyclizate to 2-oxazolidone, generating amine gas treatment wastes.
External links
|
|
