Ethanolamine, commonly abbreviated as MEA, is an organic compound with the chemical formula C2H7NO and the CAS number 141-43-5. It is the simplest of the ethanolamine family, which also includes diethanolamine (DEA) and triethanolamine (TEA). Because its molecule contains both a hydroxyl group and an amino group, MEA behaves as both an alcohol and a primary amine, giving it a unique combination of reactivity and solvency that supports a remarkably broad range of applications.
What Is Ethanolamine (MEA)?
Monoethanolamine is a colorless, viscous, hygroscopic liquid at room temperature, with a mild ammonia-like odor. It is fully miscible with water and soluble in ethanol, acetone and glycols, while it dissolves many organic compounds and reacts readily with acids, carbon dioxide and epoxides.
The compound is produced industrially by reacting ethylene oxide with aqueous ammonia, which yields a mixture of MEA, DEA and TEA that is separated by distillation. Its dual functionality means that MEA can be converted into alkanolamide surfactants, esterquats, soaps of fatty acids, and chelating or neutralizing agents, making it a versatile building block for downstream chemical production.
Key Specifications of Monoethanolamine
| Item | Standard |
|---|---|
| Product name | Monoethanolamine / MEA / 2-Aminoethanol |
| Purity | ≥ 99% |
| CAS number | 141-43-5 |
| EINECS number | 205-483-3 |
| Appearance | Colorless transparent liquid |
| Melting point | 10-11 °C |
| Boiling point | 170 °C |
| Density | 1.012 g/mL at 25 °C |
| Flash point | Approximately 93 °C |
| Water solubility | Miscible |
| Molecular formula | C2H7NO |
Commercial MEA is supplied in industrial, technical and higher-purity grades. The typical applications grade has a purity of at least 99%, with tightly controlled limits on water, color and diethanolamine content. Buyers should request a certificate of analysis confirming purity, density, water content and amine value before acceptance.
Personal Care and Cosmetic Applications
In personal care products, ethanolamines such as MEA function as cleansing agents, or surfactants, that help remove dirt and oil from skin and hair by dissolving grease and emulsifying oily residues. Because MEA does not impart a strong odor, it is commonly used in hair dyes, shampoos, body washes and facial cleansers where a neutral scent profile is desired.
MEA also acts as a pH adjuster, keeping product formulations within the range that prevents degradation of active ingredients and ensures skin compatibility. In creams and lotions, it neutralizes fatty acids to form soap-like emulsifiers that stabilize the oil-water interface. Cosmetic-grade MEA must meet strict purity requirements, and formulators should verify compliance with the cosmetics regulations of their target markets.
Cleaning and Household Product Applications
In household and industrial cleaning products, MEA neutralizes acidic residues, saponifies fats and oils, and stabilizes detergent formulations. It is found in all-purpose cleaners, floor strippers, oven cleaners, laundry detergents and metal degreasers, where its alkalinity boosts cleaning power without the harshness of caustic soda in some formulations.
In metalworking, MEA is used in water-based cutting fluids and corrosion inhibitors, where it buffers the fluid and protects ferrous surfaces. It is also a component of cement grinding aids, which improve the efficiency of clinker grinding and the flowability of cement powder.
Industrial Applications: Gas Treatment and Synthesis
The largest industrial use of MEA is in gas sweetening, where aqueous solutions of monoethanolamine absorb acid gases such as carbon dioxide and hydrogen sulfide from natural gas, refinery gas and flue streams. The loaded solution is regenerated by heating, releasing the acid gases and recycling the amine, which makes the process economical at large scale.
In chemical synthesis, MEA is used to manufacture non-ionic detergents, emulsifiers, alkanolamides, textile auxiliaries, pharmaceutical intermediates, and additives for lubricants and fuels. It reacts with fatty acids to form soap and amide surfactants, with carbon disulfide to form vulcanization accelerators, and with ethylene oxide to extend the ethanolamine chain. These derivatives serve the detergent, agrochemical, personal care and oilfield chemical industries.
Safety, Handling and Regulatory Notes
MEA is corrosive to skin, eyes and mucous membranes, and its vapors can irritate the respiratory tract. Personal protective equipment, including chemical-resistant gloves, goggles and protective clothing, is required when handling the neat material. In case of skin contact, wash immediately with plenty of water.
It should be stored in corrosion-resistant, tightly closed containers, preferably made of stainless steel or lined carbon steel, in a cool, dry and well-ventilated area away from acids, oxidizers and sources of ignition. Because MEA absorbs carbon dioxide and water from the air, containers should be blanketed with dry nitrogen where long-term storage is planned. Waste and spills must be contained and disposed of in accordance with local environmental regulations.
Frequently Asked Questions
What is the difference between MEA, DEA and TEA?
MEA, DEA and TEA are the mono-, di- and tri-substituted ethanolamines formed by reacting ethylene oxide with ammonia. MEA is the smallest and most alkaline, while DEA and TEA have progressively larger molecular weights, lower alkalinity and different application profiles.
Is ethanolamine safe in cosmetics?
MEA is permitted in cosmetics in many regions when used within the concentration limits set by regulations, and it must meet purity requirements. Some markets restrict or require labeling of specific alkanolamines, so formulators should verify local compliance.
Is MEA miscible with water?
Yes, monoethanolamine is fully miscible with water in all proportions, and aqueous MEA solutions are the basis of gas sweetening and many cleaning formulations.
How is ethanolamine used in gas sweetening?
Aqueous MEA solutions absorb carbon dioxide and hydrogen sulfide from gas streams by forming heat-reversible amine salts. Heating regenerates the solution and releases the acid gases, allowing the amine to be reused in a continuous loop.
What is the flash point of monoethanolamine?
The flash point of MEA is approximately 93 °C in a closed cup, so it is classified as a combustible liquid rather than a highly flammable one, but it should still be kept away from open flames and strong oxidizers.
Is MEA used as a cement additive?
Yes, MEA is one of the amines used in cement grinding aids. Small additions improve grinding efficiency, reduce agglomeration of cement particles and enhance the flowability of the final powder.