Trolamine

• BPTrolamine
• Ph. Eur.Trolamine
• USP–NFTrolamine

Triethanolamine; TEA; tris(2-hydroxyethyl)amine; 2,2',2''-nitrilotriethanol; trolaminum

2,2',2''-Nitrilotriethanol · [102-71-6]

UNII 9O3K93S3TK · PubChem CID 7618

C6H15NO3 · 149.19

pH adjuster, buffering agent

Typical concentrations: — · Dosage forms: Semi-solid

Used widely in topical products as an alkalising agent and to neutralise carbomer gels. Combined with fatty acids such as stearic or oleic acid it forms soaps in situ that act as anionic emulsifiers for o/w creams and lotions; typically about 2–4% trolamine is used with 2–5 times its weight of fatty acid. It is also used as a buffer and to form salts of acidic drugs.

A clear, colourless to pale yellow, viscous liquid with a slight ammoniacal odour; it may solidify below room temperature. Commercial material is a mixture of bases consisting mainly of triethanolamine with smaller amounts of diethanolamine and monoethanolamine.

Density

about 1.12 g/cm³ at 20 °C

Melting point

about 20–21 °C

Boiling point

about 335 °C

pKa

about 7.8 (25 °C)

Solubility

miscible with water, ethanol (95%), methanol, acetone and glycerol; soluble in chloroform

Hygroscopicity

very hygroscopic, viscous liquid

Turns brown on exposure to air and light. Emulsions made with trolamine soaps may darken on storage. Store in an airtight, light-resistant container in a cool, dry place.

Reacts with mineral acids to form crystalline salts and esters, and with fatty acids to form soaps. It forms complexes with copper and other heavy-metal salts and reacts with reagents such as thionyl chloride. With nitrosating agents (nitrites, nitrogen oxides) it can form carcinogenic N-nitrosamines, mainly through its diethanolamine content.

Prepared commercially by reacting ethylene oxide with ammonia, which gives a mixture of mono-, di- and triethanolamine that is separated by distillation.

Used mainly in topical products. It can irritate the skin, eyes and mucous membranes, especially at high concentrations or with prolonged contact, and allergic contact dermatitis has been reported. Contamination with or formation of nitrosamines is the main safety concern.

Observe normal precautions for the quantity handled. It is an irritant; wear eye protection and gloves and avoid inhaling vapour or mist.

Included in the FDA Inactive Ingredient Database (topical, ophthalmic, rectal, vaginal and oral preparations) and in non-parenteral medicines licensed in Europe. Its use in cosmetics is restricted, with limits on secondary amine and nitrosamine content.

Diethanolamine; monoethanolamine; tromethamine.

Avoid combining trolamine with nitrite-containing materials or other nitrosating agents, and specify low diethanolamine content. Trolamine stearate creams are pH-sensitive and break if the pH falls far enough to re-form the free fatty acid.