n-Hexane

About This Product

n-Hexane is offered in five grades, and a single figure separates them: how much of an otherwise mixed C6 refinery cut is the straight-chain isomer (C6H14, CAS 110-54-3). In the 60, 70 and 80 percent grades the rest is branched and cyclic C6 hydrocarbons, chiefly the methylpentanes and methylcyclopentane. The 97 and 99 percent grades come close to a single compound, at typically 97.8 and 99.5 percent n-hexane, against a typical 84 percent for the 80 percent grade.

For an oilseed plant processing soybean, rapeseed or similar seeds, the isomer content is of no consequence. What the plant needs is a tight boiling range, here 64–70 °C, so that the solvent can be stripped out and recycled cleanly, along with low evaporation residue, benzene and sulphur. EU Directive 2009/32/EC lists hexane among the solvents permitted for producing edible fats and oils, on condition that the residue left in the finished oil is within its limits.

The 97 and 99 percent grades serve work that depends on one defined component: pharmaceutical extraction, catalyst and polymerisation slurries such as those in polyolefin production, and laboratory use. Other outlets are botanical extraction, solvent duty in adhesives and rubber, and electronics cleaning. Whatever the grade, the product is a clear, colourless, volatile paraffin that is insoluble in water and takes up oils, fats, waxes and many resins.

Exposure has to be managed. The body metabolises n-hexane to 2,5-hexanedione, a compound that damages nerves, so occupational exposure limits are strict, and some adhesive and cleaning users move to isomer blends low in n-hexane.

BG Petro Chemicals specifies each grade for density, boiling range, bromine index, evaporation residue, sulphur, benzene and lead, and packs it in 132 kg drums or ISO tanks. The product is highly flammable (UN 1208, Class 3, PG II) and repeated exposure can harm the nervous system; handle it in line with the safety data sheet.