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 4 H227—Combustible liquid
Acute toxicity, oral, category 4 H302—Harmful if swallowed Chemical Safety Warning
Acute toxicity, dermal, category 4 H312—Harmful  in contact with skin Chemical Safety Warning
Skin corrosion/irritation, category 1B H314—Causes severe skin burns and eye damage Chemical Safety Warning
Serious eye damage/eye irritation, category 1 H318—Causes serious eye damage Chemical Safety Warning
Acute toxicity, inhalation, category 4 H332—Harmful if inhaled Chemical Safety Warning
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3 H335—May cause respiratory irritation Chemical Safety Warning
Short-term (acute) aquatic hazard, category 2 H401—Toxic to aquatic life Chemical Safety Warning
Long-term (chronic) aquatic hazard, category 3 H412—Harmful to aquatic life with long-lasting  effects Chemical 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 formula C2H7NO3
Molar mass 61.08 g/mol
Appearance Viscous colorless liquid
Melting point 10.5 °C
Boiling point 171 °C
Water solubility Miscible
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