Diethanolamine

Description

Diethanolamine (DEA): A Deeper Look at a Versatile Yet Scrutinized Compound

Diethanolamine, commonly abbreviated as DEA, is an organic compound with the chemical formula (C2H4OH)2NH. It is a colorless, viscous liquid that functions as both a secondary amine and a dialcohol. This dual nature gives DEA its unique chemical properties, making it a highly versatile compound used across a wide range of industrial and consumer applications. However, its presence, particularly in personal care products, has also made it the subject of significant scrutiny due to potential health concerns.

Chemical Properties and Classification

DEA is part of the alkanolamine family, which are organic compounds containing both alcohol (hydroxyl) and amine functional groups. Its structure features two ethanol groups attached to a nitrogen atom. This molecular architecture allows it to exhibit properties typical of both alcohols (e.g., solubility in water, ability to form esters) and amines (e.g., basicity, ability to react with acids).

It is soluble in water, alcohol, and acetone, and has a mild, ammonia-like odor. DEA is often confused with other alkanolamines like monoethanolamine (MEA) and triethanolamine (TEA), which share similar applications but have different chemical structures (one and three ethanol groups, respectively).

Key Applications of Diethanolamine

DEA’s versatility stems from its ability to act as a surfactant, emulsifier, pH adjuster, and chemical intermediate.

1. Personal Care and Cosmetics (Indirect Use is Key): While free DEA is rarely used directly in cosmetics, it is a crucial building block for many common ingredients. Its derivatives, such as cocamide DEA, lauramide DEA, and oleamide DEA, are widely employed. These derivatives act as:
   • Foam Boosters: Enhancing the lather and stability of foam in shampoos, body washes, and soaps.
   • Thickening Agents: Contributing to the viscosity of liquid products.
   • Emulsifiers: Helping to blend oil and water-based ingredients, creating stable formulations in lotions and creams.
   • Emollients: Providing a smooth feel to skin and hair.
2. Industrial Applications:
   • Gas Sweetening: DEA is extensively used in the natural gas and oil refining industries to remove acidic gases like hydrogen sulfide (H2S) and carbon dioxide (CO2) from gas streams. This process, known as “gas sweetening” or “acid gas removal,” improves the quality and safety of the gas.
   • Metalworking Fluids: It serves as a corrosion inhibitor and emulsifier in coolants and lubricants used in metal processing.
   • Polyurethane Foams: DEA is used as a catalyst in the production of polyurethane foams, which are found in insulation, furniture, and automotive parts.
   • Concrete Admixtures: It can act as a grinding aid and accelerator in cement production, influencing the setting time and strength of concrete.
   • Chemical Intermediate: DEA is a precursor in the synthesis of various other chemicals, including chelating agents, textile finishing agents, and some herbicides.
3. Pharmaceuticals: In controlled environments, DEA can be used as an intermediate in the synthesis of certain pharmaceutical compounds.

Safety and Health Considerations

Despite its utility, DEA has been the subject of health concerns, primarily related to its potential to form N-nitrosodiethanolamine (NDELA), a known carcinogen.

• Nitrosamine Formation: The main concern arises when DEA (or its derivatives) comes into contact with nitrosating agents (e.g., nitrites, nitrates), which can be present as impurities in raw materials or form during manufacturing or storage of products. This reaction forms NDELA. The International Agency for Research on Cancer (IARC) classifies NDELA as a Group 2B probable human carcinogen.
• Skin and Eye Irritation: Direct contact with concentrated DEA can cause skin and eye irritation. However, in consumer products, the concentrations are typically much lower, reducing the risk of acute irritation.
• Regulatory Scrutiny: Regulatory bodies worldwide have addressed the concerns related to DEA and NDELA.
  • European Union (EU): The EU Cosmetics Regulation significantly restricts the use of DEA and its derivatives in cosmetic products, especially in those that are combined with nitrosating agents. There are mandates to ensure that the maximum nitrosamine content does not exceed specified limits.
  • United States (FDA): While the FDA has not outright banned DEA for cosmetic use, it has advised manufacturers to avoid raw materials containing nitrosating agents and to minimize the formation of nitrosamines in finished products.
  • State Regulations: In California, DEA is listed under Proposition 65 as a chemical known to cause cancer.

It’s important to differentiate between direct exposure to DEA and potential exposure to its nitrosamine byproducts. The primary concern in consumer products is the formation of NDELA over time, rather than the DEA itself.

Alternatives and Future Outlook

Due to regulatory pressures and consumer demand for “cleaner” products, the personal care industry has increasingly moved away from DEA and its common derivatives (like Cocamide DEA) in favor of alternatives. These include:

• Betaines (e.g., Cocamidopropyl Betaine): Often used for foam boosting and mild cleansing.
• Sulfosuccinates (e.g., Disodium Laureth Sulfosuccinate): Provide cleansing and foaming properties.
• Amine Oxides (e.g., Cocamidopropylamine Oxide): Act as foam stabilizers and thickeners.
• Non-DEA Alkanolamides: Newer generations of alkanolamides designed to minimize nitrosamine formation.

In industrial applications, DEA remains a vital chemical due to its cost-effectiveness and efficiency, particularly in gas sweetening. However, research continues into substitute processes and compounds that could offer similar performance with reduced environmental or health impacts.

Conclusion

Diethanolamine is a compound with a dual identity: a highly effective and versatile chemical indispensable in various industrial processes, and a scrutinized ingredient in consumer products due to its potential to form carcinogenic nitrosamines. As scientific understanding evolves and regulatory landscapes shift, the uses of DEA continue to be refined, with a clear trend in consumer goods towards safer alternatives and stricter controls to minimize potential risks. For consumers, understanding the distinction between DEA and its problematic byproducts, and being aware of product formulations, remains key.