Is Diethanolamine Organic or Inorganic?
Diethanolamine is an organic compound. It belongs to the alkanolamine family: a secondary amine carrying two 2-hydroxyethyl groups on the nitrogen. Its molecular formula is C4H11NO2, its molecular weight is 105.14, and its CAS number is 111-42-2. It is a colourless to pale yellow viscous liquid with a mild ammonia odour, and it is fully miscible with water, alcohols and many polar solvents.
The presence of both an amine nitrogen and two hydroxyl groups is the reason the molecule behaves as it does: the nitrogen supplies basicity and the capacity to form salts and amides, while the hydroxyl groups supply water compatibility, hydrogen bonding and emulsifying action.
Chemical Identity at a Glance
| Parameter | Value |
|---|---|
| CAS number | 111-42-2 |
| Molecular formula | C4H11NO2 |
| Molecular weight | 105.14 |
| Chemical class | secondary alkanolamine (organic base) |
| Appearance | colourless to pale yellow viscous liquid |
| Boiling point at 101.3 kPa | about 268 C |
| Melting point | about 28 C, so the neat product can crystallise at low ambient temperature |
| Density at 20 C | about 1.09 g/cm3 |
| pKa at 25 C | about 8.9 |
| Solubility | miscible with water, methanol, ethanol and acetone |
Why DEA Works as an Emulsifier and pH Adjuster
DEA is amphiphilic in a mild sense: the hydroxyethyl groups are hydrophilic while the hydrocarbon backbone is not. Neutralised with a fatty acid it forms a soap that reduces interfacial tension and stabilises oil-in-water systems, which is the basis of its use as an emulsifier in coatings, inks, plastics and metalworking fluids. As a weak organic base with a pKa near 8.9, it buffers in a useful pH band and can raise the pH of a formulation without the sharp effect of an inorganic alkali. It also acts as a wetting and flow agent, improving levelling and gloss.
Principal Industrial Uses
1. Coatings, inks and plastics: emulsifier, dispersant and flow promoter for pigment concentrates and resin systems.
2. Gas treating: a component of aqueous amine blends used to scrub carbon dioxide and hydrogen sulphide from process and natural gas streams.
3. Detergents, soaps and personal care: pH control and foam structure, and as an amide or ester building block for surfactants.
4. Agrochemical formulations: emulsifier systems for emulsifiable concentrates.
5. Textile and metal processing: wetting agents, lubricant components and corrosion-inhibiting formulations.
6. Chemical synthesis: intermediate for amides, esters and morpholine-type derivatives.
Quality Tests and Specification Points
A practical purchase specification for DEA rests on a short set of methods that can be run in any industrial laboratory. Water content is normally determined by Karl Fischer titration under ASTM D1364, colour is read on the platinum-cobalt scale under ASTM D1209, and acidity or alkalinity is titrated to a defined end point. Purity and the distribution of mono-, di- and triethanolamine are resolved by gas chromatography, and the total amine value is obtained by titration. Because the product solidifies near 28 C, the water content of the delivered lot is worth checking alongside the appearance, since moisture uptake changes both the assay and the freezing behaviour.
Safe Handling, Storage and Regulatory Context
Store DEA in a cool, dry, well-ventilated area away from heat, open flame and direct sunlight, in closed containers under a nitrogen blanket where the product is held long term. Because the melting point is close to ambient, tanks and transfer lines in cool climates are normally heat traced or held above 30 C to keep the material pumpable. Avoid contact with strong oxidising acids. During handling, wear chemical protective goggles, impervious gloves and protective clothing, and use local extraction where vapour or mist can be generated; if a person shows signs of discomfort after exposure, they should be removed from the area and referred for medical assessment.
From a regulatory standpoint, DEA has been classified as possibly carcinogenic to humans (Group 2B) in the IARC monograph series, and cosmetic use of secondary alkanolamines is restricted under Regulation (EC) No 1223/2009 where nitrosamine formation is possible. Classification, labelling and packaging in the EU are governed by Regulation (EC) No 1272/2008. Buyers should confirm the current classification and any destination-market restriction before the material is shipped.
Frequently Asked Questions
Q: Is diethanolamine organic or inorganic?
A: It is organic. DEA is a secondary alkanolamine with the formula C4H11NO2 and CAS number 111-42-2.
Q: Why does DEA sometimes arrive as a solid?
A: Its melting point is about 28 C, so in cool weather or a cold warehouse the neat product can crystallise. Warming the container gently restores the liquid state without damaging the product.
Q: What makes DEA useful as an emulsifier?
A: Two hydroxyethyl groups give it water compatibility while the carbon backbone provides an oil-compatible part, so it stabilises oil-in-water dispersions and improves wetting and flow.
Q: How is DEA purity normally confirmed?
A: By gas chromatography, which also resolves the mono-, di- and triethanolamine distribution, supported by titration of the total amine value.
Q: Which test methods are commonly written into a DEA specification?
A: ASTM D1364 for water content by Karl Fischer titration and ASTM D1209 for colour on the platinum-cobalt scale, together with gas chromatography for purity and titration for acidity or alkalinity.
Q: Are there regulatory restrictions on DEA in cosmetics?
A: Yes. Secondary alkanolamines are restricted under Regulation (EC) No 1223/2009 where nitrosamine formation is possible, and DEA is listed as possibly carcinogenic to humans (Group 2B) in the IARC monographs.