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.
Almost all 2-ethylhexanol manufactured is used as a precursor for the synthesis of the diester bis(2-ethylhexyl) phthalate (DEHP), 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 an octane booster when reacted with nitric acid.
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.
Synthesis of 2-Ethylhexanol
The n-butyraldehyde 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. The overall process is very similar to that of the Guerbet reaction, by which it may also be produced.
2-Ethylhexanol exhibits low toxicity in animal models, with LD50 ranging from 2-3 g/kg (rat).
Although isooctanol (and the derived isooctyl prefix) is commonly used in industry to refer to 2-ethylhexanol and its derivatives, IUPAC naming conventions dictate that this name is properly applied to another isomer of octanol, 6-methylheptan-1-ol. The Chemical Abstracts Service likewise indexes isooctanol (CAS# 26952-21-6) as 6-methylheptan-1-ol.