Triethanolamine (2-[bis(2-hydroxyethyl)amino]ethanol) or TEA, is a chemical compound, a triol and a tertiary amine compound derived from ammonia. It belongs to the ethanolamine family to which monoethanolamine (MEA) and diethanolamine (DEA) belong and was introduced to the market in 1920. Ethanolamines as amines react with acids to form soaps or salts and as alcohols can be esterified and are hygroscopic.

The name describes the structure of the molecule:

• "Tri-" indicates "three", so "Triethanolamine" means that there are three ethanol  groups in the molecule.
• "Ethanol" refers to ethyl alcohol, also known as ethanol, which is a common chemical compound. The presence of three ethanol groups indicates that Triethanolamine contains three -OH groups derived from ethanol.
• "Amine" indicates that the molecule contains an amino group (-NH₂) or a derivative of an amine. In Triethanolamine, the amino group is attached to the central carbon of the molecule.

The synthesis process takes place in different steps:

• Preparation of reagents. The main raw materials include ammonia (NH₃) and ethylene oxide (C₂H₄O).
• Ethoxylation reaction. Ammonia is reacted with ethylene oxide. This reaction produces ethanolamines. Specifically, triethanolamine is obtained through the reaction of ammonia with three moles of ethylene oxide.
• Mixing and temperature control. The reaction is carried out in a reactor, with temperature control to ensure a safe and efficient reaction. Typically, the reaction occurs at moderate temperatures.
• Distillation. The crude product of the reaction contains a mixture of mono-, di-, and triethanolamines. The mixture is purified through fractional distillation to separate triethanolamine from other ethanolamines and impurities.
• Purification. The distilled triethanolamine is further purified to remove any traces of impurities using techniques such as crystallization or ultrafiltration.
• Stabilization. The purified triethanolamine is stabilized to ensure its stability during transportation and storage, preventing degradation.
• Quality control. The triethanolamine undergoes rigorous quality testing to ensure it meets standards for purity, efficacy, and safety. These tests include chemical analysis, spectroscopy, and microbiological testing.

It occurs as a colourless liquid.

Cosmetics

Component added as a chemical intermediate for anionic and non-ionic surfactants, softening humectant and emulsifying agent in shampoos, lotions, creams and other cosmetics acting as a pH regulator.

It is a restricted ingredient III/62 as a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Substance or ingredient reported:     Trialkylamines, trialkanolamines and their salts. Maximum concentration in ready for use preparation, Leave-on products or Rinse-off products: 2,5%. Do not use with nitrosating systems - Minimum purity: 99% - Maximum secondary amine content: 0.5% (applies to raw materials) - Maximum nitrosamine content: 50 microgram/kg - Keep in nitrite-free containers

As an INCI ingredient, it acts as follows:

• Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.
• Fragrance. It plays a decisive and important role in the formulation of cosmetic products as it provides the possibility of enhancing, masking or adding fragrance to the final product, increasing its marketability.  The consumer always expects to find a pleasant or distinctive scent in a cosmetic product.
• Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 
• Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable and are used to soothe or soften the skin and emulsify, so they need a specific, stabilising ingredient. This ingredient forms a film, lowers the surface tension and makes two immiscible liquids miscible. A very important factor affecting the stability of the emulsion is the amount of the emulsifying agent. Emulsifiers have the property of reducing the oil/water or water/oil interfacial tension, improving the stability of the emulsion and also directly influencing the stability, sensory properties and surface tension of sunscreens by modulating the filmometric performance.

Industry

Stabiliser and pH adjuster for the treatment of polyester surface aminolysis.

Other applications

Solvent and reagent. Used in detergents and household cleaning products, textiles, agricultural herbicides, mineral and vegetable oils, paraffin and waxes, pharmaceutical ointments, petroleum extraction, synthetic resins, plasticisers, adhesives and sealants.

Vulcanisation activator for natural and synthetic rubber, activator in the polymerisation of nitrile rubber.

Safety

It is considered a potentially toxic and pro-inflammatory compound (1).

The most relevant studies on this ingredient have been selected with a summary of their contents:

Triethanolamine studies

Appearance	Colorless liquid
Boiling Point	335.4±0.0 °C at 760 mmHg
Melting Point	21°C
Flash Point	185.0±0.0°C
Density	1.2±0.1 g/cm3
Index of Refraction	1.511
Vapour Pressure	0.0±1.6 mmHg at 25°C
Vapour density	5.14
PSA	63.93000
LogP	-1.11
Safety

• Molecular Formula  C₆H₁₅NO₃   (HOCH₂CH₂)₃N
• Molecular Weight     149.19
• Exact Mass   149.105194
• CAS  102-71-6
• UNII    9O3K93S3TK
• EC Number   203-049-8
• DSSTox Substance ID  DTXSID9021392
• IUPAC  2-[bis(2-hydroxyethyl)amino]ethanol
• InChI=1S/C6H15NO3/c8-4-1-7(2-5-9)3-6-10/h8-10H,1-6H2
• InChl Key      GSEJCLTVZPLZKY-UHFFFAOYSA-N
• SMILES   C(CO)N(CCO)CCO
• MDL number  MFCD00002855
• PubChem Substance ID    57653380
• ChEBI  28621
• ICSC    1034
• NSC   36718
• RTECS   KL9275000
• Beilstein   1699263
• NACRES  NA.25   

Synonyms:

• Tris(2-hydroxyethyl)amine, 2,2′,2′′-Nitrilotriethanol
• Trolamine
• Tris(2-hydroxyethyl)amine

References_____________________________________________________________________

(1) Hu X, Zhou R, Li H, Zhao X, Sun Y, Fan Y, Zhang S. Alterations of Gut Microbiome and Serum Metabolome in Coronary Artery Disease Patients Complicated With Non-alcoholic Fatty Liver Disease Are Associated With Adverse Cardiovascular Outcomes. Front Cardiovasc Med. 2022 Jan 3;8:805812. doi: 10.3389/fcvm.2021.805812.