What Is 2-Ethylhexanol (CAS 104-76-7)?
2-Ethylhexanol, usually shortened to 2-EH, is a branched primary alcohol built from eight carbon atoms. Its molecular formula is C8H18O and its CAS Registry Number is 104-76-7. The material is a clear, colourless liquid with a mild odour, and it ranks among the highest-volume industrial alcohols traded worldwide.
Commercially the alcohol is produced by aldol condensation of n-butyraldehyde followed by hydrogenation of the unsaturated aldehyde intermediate. Purified product is normally supplied at a minimum assay of 99.5 % and is miscible with most common organic solvents, while its solubility in water stays limited to roughly 0.07 g per 100 mL.
Flash Point and Flammability Classification
The closed-cup flash point of 2-ethylhexanol is approximately 81 °C, equivalent to about 178 °F. The flash point is the lowest temperature at which the vapour layer above the liquid can form an ignitable mixture with air when an ignition source is introduced, so it directly governs labelling, storage and transport rules.
Because 81 °C sits well above the 60 °C threshold used by most regulatory systems, the material is handled as a combustible liquid rather than a flammable liquid. In practice this means it does not require the same explosion-proof regime as a low-flash solvent, but it will still burn once heated above its flash point or finely atomised into a mist.
The auto-ignition temperature lies near 270 °C and vapour pressure at ambient conditions is low, so evaporation from an open surface is slow. Both figures matter for distillation, drying and ventilation design in plants that store or process the alcohol.
Key Physical Properties at a Glance
| Property | Typical value |
|---|---|
| CAS Registry Number | 104-76-7 |
| Molecular formula | C8H18O |
| Molecular weight | 130.23 g/mol |
| Appearance | Clear, colourless liquid |
| Flash point, closed cup | approx. 81 °C / 178 °F |
| Boiling point at 101.3 kPa | approx. 185 °C |
| Auto-ignition temperature | approx. 270 °C |
| Density at 20 °C | approx. 0.833 g/cm3 |
| Water solubility | approx. 0.07 g/100 mL |
| Hazard class | Combustible liquid, flash point above 60 °C |
Industrial Applications of 2-Ethylhexanol
Plasticiser production – esterification with phthalic anhydride or terephthalic acid yields the plasticisers that soften PVC compounds for cable, flooring and film.
Acrylate monomers – 2-ethylhexyl acrylate is a backbone monomer for coatings, pressure-sensitive adhesives and sealants.
Solvents and coalescing aids – used in paints, printing inks and industrial cleaning formulations.
Lubricant and fuel additives – esters act as base stocks, pour-point improvers and anti-wear components.
Surfactant and agrochemical intermediates – the alcohol is ethoxylated or phosphated to build downstream chemistry.
Defoamers and process aids – its low water solubility is useful wherever aqueous foaming must be suppressed.
Storage, Handling and Fire Safety
Keep 2-ethylhexanol in sealed, correctly labelled containers in a cool, dry and well-ventilated area, away from strong oxidising agents, heat sources and open flames. Exclude ignition sources from the storage zone, and bond and earth transfer lines whenever the liquid is pumped in bulk.
Wear chemical-resistant gloves, safety goggles and suitable work clothing when decanting or sampling. Wash skin thoroughly with water and soap after any contact, and ventilate confined spaces before entry because the vapour is heavier than air in still conditions. For spills, dyke the liquid, keep it away from drains and watercourses, and absorb it with inert material before disposal under local regulations.
When the product is heated above ambient temperature, for example in distillation or blending, review the exposure limits and control measures listed in the safety data sheet for the grade in use.
Frequently Asked Questions
Q: What is the flash point of 2-ethylhexanol?
The closed-cup flash point is approximately 81 °C, which is about 178 °F.
Q: Is 2-ethylhexanol flammable or combustible?
It is classified as a combustible liquid because its flash point is above 60 °C, though it can still burn when heated or atomised.
Q: What is the boiling point of 2-ethylhexanol?
The normal boiling point is approximately 185 °C at standard atmospheric pressure of 101.3 kPa.
Q: What is 2-ethylhexanol used for?
Its main outlets are plasticiser production, 2-ethylhexyl acrylate monomer, coatings and inks, lubricant additives, defoamers and surfactant intermediates.
Q: Is 2-ethylhexanol soluble in water?
Only slightly, about 0.07 g per 100 mL, but it mixes freely with most organic solvents.
Q: What is the chemical formula and CAS number of 2-ethylhexanol?
The formula is C8H18O, the CAS Registry Number is 104-76-7 and the molecular weight is 130.23 g/mol.