Alkanes
DETAIL
Hexane is a significant constituent of gasoline. It is a colorless liquid, odorless when pure, and with boiling points approximately 69 °C (156 °F). It is widely used as a cheap, relatively safe, largely unreactive, and easily evaporated non-polar solvent.
The term hexanes refers to a mixture, composed largely (>60%) of hexane, with varying amounts of the isomeric compounds 2-methylpentane and 3-methylpentane, and, possibly, smaller amounts of nonisomeric C5, C6, and C7 (cyclo)alkanes. Hexanes is cheaper than hexane and is often used in large scale operations not requiring a single isomer (e.g., as cleaning solvent or for chromatography).
In industry, hexanes are used in the formulation of glues for shoes, leather products, and roofing. A typical laboratory use of hexanes is to extract oil and grease contaminants from water and soil for analysis. Hexanes are commonly used in chromatography as a non-polar solvent.
Hexanes are chiefly obtained by refining crude oil. The exact composition of the fraction depends largely on the source of the oil (crude or reformed) and the constraints of the refining. The industrial product (usually around 50% by weight of the straight-chain isomer) is the fraction boiling at 65–70 °C (149–158 °F).