2-Ethylhexanol is a branched, eight-carbon chiralalcohol. It is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. It is produced on a massive scale for use in numerous applications such as solvents, flavors, and fragrances and especially as a precursor for production of other chemicals such as emollients and plasticizers. It is encountered in natural plant fragrances, and the odor has been reported as "heavy, earthy, and slightly floral" for the R enantiomer and "a light, sweet floral fragrance" for the S enantiomer.
Properties and applications
The branching in 2-ethylhexanol inhibits its crystallization due to packing disruption; this results in a very low freezing point. Esters of 2-ethylhexanol are similarly affected and it therefore finds application as a feedstock in the production of plasticizers and lubricants, where its presence helps reduce viscosity and lower freezing points. A significant portion of 2-ethylhexanol manufactured is used as a precursor for the synthesis of the diester bis phthalate, a plasticizer. Because it is a fatty alcohol, its esters tend to have emollient properties. It is also commonly used as a low volatility solvent. 2-Ethylhexanol can also be used as a cetane number booster when reacted with nitric acid. It also used to react with epichlorohydrin and sodium hydroxide to produce the glycidyl ether of the molecule which is used as an epoxy reactive diluent in various coatings, adhesives and sealants applications. It can be used in the development of photos, production of rubber and extraction of oil and gas.
2-Ethylhexanol is produced industrially by the aldol condensation of n-butyraldehyde, followed by hydrogenation of the resulting hydroxyaldehyde. About 2,500,000 tons are prepared in this way annually. The n-butyraldeheyde is made by hydroformylation of propylene, either in a self-contained plant or as the first step in a fully integrated facility. Most facilities make n-butanol and isobutanol in addition to 2-ethylhexanol. Alcohols prepared in this way are sometimes referred to as oxo alcohols. The overall process is very similar to that of the Guerbet reaction, by which it may also be produced.
Although isooctanol is commonly used in industry to refer to 2-ethylhexanol and its derivatives, IUPACnaming conventions dictate that this name is properly applied to another isomer of octanol, 6-methylheptan-1-ol. The Chemical Abstracts Service likewise indexes isooctanol as 6-methylheptan-1-ol.
