Diethanolamine is an organic compound that is both a secondary amine and a diol. A secondary amine is a molecule containing a nitrogen atom bonded to two organic groups, while a diol is a molecule with two alcohol groups. Diethanolamine is produced by the reaction of ethylene oxide with aqueous ammonia. This reaction also produces ethanolamine and triethanolamine. Diethanolamine is soluble in water and some organic solvents. It is a colorless compound but may appear yellow due to impurities. It has a mild ammonia-like odor and solidifies below 28 °C.
The chemical and physical properties of diethanolamine are as follows:
- Chemical Formula: C4H11NO2
- Molecular Weight: 105.14 g/mol
- Melting Point: 28 °C
- Boiling Point: 268 °C
- Density: 1.096 g/mL
- Vapor Pressure: 0.01 mmHg (at 25 °C)
- Flash Point: 134 °C
- Octanol/Water Partition Coefficient (log Kow): -1.01
- Acidity (pKa): 8.8
- pH Value: 12.0 (0.1M solution)
- Solubility: High in water and some organic solvents, low in hydrocarbons
Diethanolamine has numerous applications. It is most commonly used in cosmetics, pharmaceuticals, and personal care products. In these applications, it serves as an emulsifier, foam booster, and pH regulator (acidity adjuster). Diethanolamine is used as a solvent for aqueous solutions of many intravenous drugs. It also acts as a surfactant in metalworking fluids and lubricants, a corrosion inhibitor, a dispersing agent in agricultural chemical formulations, and an intermediate in the production of other compounds, such as diethanolamine fatty acid condensates. These condensates are used as emulsifiers, thickeners, wetting agents, and detergents in soaps and cosmetics.
Some common products containing diethanolamine include:
- Shampoos: Diethanolamine is used in shampoos as a foaming agent and cleanser. It also helps regulate pH and retain moisture in hair.
- Cosmetic Products: In cosmetics, diethanolamine functions as an emulsifier and moisturizer. It also enhances the structure and texture of cosmetic formulations.
- Pharmaceuticals: Diethanolamine serves as a solvent and buffering agent in pharmaceuticals. It can also improve the bioavailability of certain drugs.
- Metalworking Fluids: Diethanolamine acts as a corrosion inhibitor and lubricant in metalworking fluids. It helps prevent rust formation on metal surfaces and improves the efficiency of metalworking processes.
- Agricultural Chemicals: Diethanolamine is an intermediate in the production of agricultural chemicals. For example, iminodiethanol, a precursor to the herbicide glyphosate, is derived from diethanolamine.
Additionally, diethanolamine is used in industrial gas treatment, textile processing, paints, inks, and complexometric titrations. Diethanolamine is a versatile chemical compound with applications across multiple industries.