Diethanolamine (DEA) is a secondary amine with the chemical formula C₄H₁₁NO₂, typically supplied at 85% concentration.
It is a colorless to pale-yellow viscous liquid with a mild ammonia-like odor.
DEA is widely used in resin manufacturing, gas treatment, detergents, paints, pharmaceuticals, and various industrial formulations.
In industrial processes, it acts as a pH adjuster, catalyst, neutralizing agent, and emulsifier.

Chemical Structure

Molecular Formula: C₄H₁₁NO₂
Molecular Weight: 105.14 g/mol
Structure: Contains two hydroxyl (-OH) groups and one secondary amine (-NH) group.
Solidifies into deliquescent crystals that form a viscous liquid upon melting.

Physical and Chemical Properties

Property	Typical Value
Physical State	Viscous liquid or meltable crystals
Color	Colorless to pale yellow (≤15 APHA)
Odor	Ammoniacal / fishy
Density (20 °C)	1.09 g/mL
Melting Point	≈ 28 °C
Boiling Point	≈ 268 °C (at 1 atm)
Viscosity (30 °C)	≈ 352 cP
Vapor Pressure (20 °C)	< 0.01 mmHg (~0.00037 hPa)
Solubility in Water	Completely miscible
Refractive Index (nᴅ)	≈ 1.477
pKa (25 °C)	≈ 8.9
Explosion Range (air)	1.6–9.8% (v/v)
Ecotoxicity	Harmful to aquatic life with long-term effects

Key Advantages

Bifunctional molecule — contains both amine and hydroxyl groups, enabling diverse chemical reactivity.
Effective pH regulator and catalyst in resin production, polyurethane foams, detergents, agrochemicals, and cosmetics.
High solubility in water and polar solvents; easily blends with various formulations.
Capable of absorbing acidic gases (CO₂, H₂S) in gas treatment systems.

Limitations and Hazards

Corrosive to skin and eyes — may cause severe burns or tissue damage.
Toxic upon chronic exposure — prolonged inhalation or contact may harm the liver, kidneys, or blood system.
- Oral LD₅₀ (rat): ≈ 1.6 g/kg
Harmful to aquatic organisms — must be neutralized or diluted before disposal.
Incompatible with strong acids, oxidizers, and acid chlorides (may cause exothermic reactions).

Industrial Applications

Gas Sweetening:
Absorption of CO₂ and H₂S from natural gas and process streams.
Paints, Resins & Adhesives:
Used as a catalyst, stabilizer, and neutralizing agent in epoxy and alkyd systems.
Detergents & Personal Care:
pH adjustment, foam stabilizer, and emulsifier in soaps and cosmetic formulations.
Pharmaceutical & Cosmetic Industry:
Intermediate in the production of emollients, conditioners, and surface-active agents.
Agrochemicals:
Solvent and intermediate for fertilizers and pesticide formulations.
Other Uses:
Emulsion additive in photographic chemicals and cement admixtures to enhance performance.

Safety and Handling

Main Hazards:

Strong irritant to skin and eyes
May be absorbed through the skin and cause systemic toxicity
Harmful to aquatic environments

Personal Protective Equipment (PPE):

Chemical-resistant gloves and protective clothing
Safety goggles or face shield
Adequate ventilation or respiratory protection (P2/P3 filter) in confined spaces

Storage Conditions:

Store in a cool, dry, well-ventilated area
Keep away from acids, oxidizing agents, and heat sources
Maintain temperature below the melting point (≈ 28 °C) to prevent solidification
Use tightly sealed containers with clear labeling

Emergency Measures:

Skin contact: Wash immediately with plenty of water and soap
Eye contact: Rinse continuously with water for at least 15 minutes and seek medical attention
Inhalation: Move victim to fresh air; administer oxygen if necessary
Spill cleanup: Absorb with inert materials and dispose according to environmental regulations

Summary:
Diethanolamine (DEA 85%) is a versatile industrial chemical with strong pH-regulating, emulsifying, and gas-absorbing properties.
It plays a critical role in gas purification, resin synthesis, detergents, and personal care formulations.
Proper handling, protective measures, and controlled use are essential due to its corrosive and toxic nature.