Hexane
Properties
| State | Liquid (volatile) |
| Color | Colorless |
| Solubility | Immiscible with water; miscible with most organic solvents |
| Melting Point | -95.3°C |
| Boiling Point | 69°C |
About Hexane
Hexane is the workhorse nonpolar solvent of any organic chemistry lab — a colorless, volatile straight-chain alkane (CH3(CH2)4CH3) with a molar mass of 86.175 g/mol and a boiling point at 69 °C that's low enough to evaporate from a rotovap in minutes but high enough that you can actually run a column without losing half your eluent. Most labs don't actually buy n-hexane; they buy 'hexanes' (plural), the cheaper distillation cut from petroleum that's a mixture of n-hexane, 2-methylpentane, 3-methylpentane, and methylcyclopentane. For routine flash chromatography on silica, hexanes/ethyl acetate gradients (anywhere from 95:5 for nonpolar terpenes to 50:50 for polar amides) are the default first thing to try. The pure n-hexane isomer is reserved for spectroscopy (UV cutoff around 195 nm) and HPLC where isomeric purity matters. Industrially, hexane is the dominant solvent for soybean oil extraction — roughly 200 million tonnes of soybeans get processed this way each year, with the hexane recovered by steam stripping and recycled. The n-hexane isomer specifically is metabolized to 2,5-hexanedione, which crosslinks neurofilament proteins in axons; this is why long-term shoe-factory workers exposed to hexane glues developed peripheral neuropathy in the 1970s.
Where you'll encounter it
If you've ever stripped a column with 100% hexanes after running a nonpolar reaction, smelled the gasoline-like fumes when opening a fresh 4 L bottle, or eaten anything containing soybean oil (which is essentially everything processed), you've encountered hexane. Every academic and industrial organic chemistry lab on Earth keeps 4 L bottles of hexanes within arm's reach of the rotovap — it's the default first solvent to try in flash chromatography on silica, paired with ethyl acetate gradients from 95:5 for nonpolar terpenes to 50:50 for polar amides. Industrial soybean processors at ADM and Cargill plants run roughly 200 million tonnes of soybeans through hexane extraction per year, recovering the solvent by steam stripping and recycling it through the system. Rubber-cement and contact-adhesive formulations use hexane as the volatile carrier that flashes off after application.
Common Uses
- Mobile phase in normal-phase silica column chromatography (with EtOAc gradients)
- Industrial soybean and rapeseed oil extraction by steam stripping
- Solvent for rubber cement, contact adhesives, and shoe glues
- Degreasing agent for precision metal parts before electroplating
- Reference nonpolar solvent for partition coefficient (logP) measurements
- UV-spectroscopy solvent (cutoff ~195 nm) when isomerically pure
- Extraction solvent for natural product chemistry (terpenes, lipids)
Safety Information
Highly flammable (flash point -22 °C) — keep away from sparks and static. The n-hexane isomer is a confirmed peripheral neurotoxin: chronic inhalation produces 2,5-hexanedione, which crosslinks neurofilaments and causes glove-and-stocking neuropathy. OSHA PEL is 500 ppm (8-hr TWA); ACGIH TLV is much stricter at 50 ppm. GHS: H225 (flammable), H304 (aspiration hazard — fatal if swallowed), H315 (skin irritation), H336 (drowsiness/dizziness), H361f (suspected reproductive toxicity), H373 (organ damage from prolonged exposure), H411 (toxic to aquatic life). Use only in a fume hood, ground all metal containers when transferring, and never mouth-pipette.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.