July 05, 2021
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Ethanolamine, formally 2-aminoethanol, is a viscous, alkaline liquid with an unpleasant, ammonia-like odor. It is miscible in all proportions with water and several oxygenated organic solvents, including methanol, acetone, and glycerol. As the hazard information table shows, it is hazardous to humans and the environment.

In one of the earliest literature references to ethanolamine (1897), noted chemist Ludwig Knorr at the University of Jena (Germany) made the compound on a large scale by treating ethylene oxide with ammonia. The author cited work from as early as 1860 in which researchers made ethanolamine salts but could not isolate the free base. More recent ethanolamine research included synthesis from nitromethane and formaldehyde, but the prevailing manufacturing method still goes back to Knorr’s work.

Ethanolamine has several important industrial uses: as a “scrubber” to remove carbon dioxide, hydrogen sulfide, and other acidic pollutants from waste gas streams; as a starting material for manufacturing surfactants, chelating agents, and even pharmaceuticals; as an agent for softening leather; and as an additive for controlling pH in industrial water streams.

What’s new with ethanolamine? As with several recent Molecules of the Week, it has been discovered in outer space. Víctor M. Rivilla, Belén Tercero, Sergio Martín, and colleagues in Spain, Italy, Japan, Chile, and the United States identified ethanolamine in a molecular cloud in the interstellar medium, specifically in a complex in the Milky Way’s Galactic Center.

More than most molecules found in space, ethanolamine has particular relevance to possible origins of life on Earth. It is present in the water-soluble “heads” of phospholipids, which form all known cell membranes. And it could be a direct precursor of glycine, the simplest amino acid, which has been detected in the comet 67P/Churyumov–Gerasimenko.

Rivilla et al. conclude that their results “indicate that ethanolamine forms efficiently in space and, if delivered onto early Earth, could have contributed to the assembling and early evolution of primitive membranes.”

Ethanolamine hazard information

Hazard class*Hazard statement
Flammable liquids, category 4H227—Combustible liquid
Acute toxicity, oral, category 4H302—Harmful if swallowedChemical Safety Warning
Acute toxicity, dermal, category 4H312—Harmful  in contact with skinChemical Safety Warning
Skin corrosion/irritation, category 1BH314—Causes severe skin burns and eye damageChemical Safety Warning
Serious eye damage/eye irritation, category 1H318—Causes serious eye damageChemical Safety Warning
Acute toxicity, inhalation, category 4H332—Harmful if inhaledChemical Safety Warning
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3H335—May cause respiratory irritationChemical Safety Warning
Short-term (acute) aquatic hazard, category 2H401—Toxic to aquatic lifeChemical Safety Warning
Long-term (chronic) aquatic hazard, category 3H412—Harmful to aquatic life with long-lasting  effectsChemical Safety Warning

*Globally Harmonized System of Classification and Labeling of Chemicals.  
Explanation of pictograms.

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Ethanolamine fast facts

CAS Reg. No.141-43-5
Ethanol, 2-amino-
Empirical formulaC2H7NO3
Molar mass61.08 g/mol
AppearanceViscous colorless liquid
Melting point10.5 °C
Boiling point171 °C
Water solubilityMiscible
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