| HS Code | |
| Product Name | N-Hexane |
| Cas Number | 110-54-3 |
| Ec Number | 203-777-6 |
| Molecular Formula | C6H14 |
| Molecular Weight | 86.18 g/mol |
| Appearance | Colorless liquid |
| Odor | Gasoline-like |
| Boiling Point | 68.7 °C |
| Melting Point | -95 °C |
| Density | 0.659 g/cm³ at 20 °C |
| Vapor Pressure | 17.6 kPa at 20 °C |
| Flash Point | -22 °C (closed cup) |
| Autoignition Temperature | 225 °C |
| Solubility | Practically insoluble in water; soluble in ethanol, ether, acetone |
| Viscosity | 0.294 mPa·s at 25 °C |
| Refractive Index | 1.375 at 20 °C |
| Logp | 3.90 |
| Explosive Limits | 1.1–7.5% (v/v) |
| Un Number | 1208 |
| Hazard Class | 3 (Flammable liquid) |
| Packing Group | II |
As an accredited N-Hexane factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | N-Hexane supplied in 20 L steel drums, labeled flammable and toxic, with UN 1208 markings. |
| Container Loading (20′ FCL) | N-Hexane loaded in a 20-foot FCL container, packed in UN-approved steel drums, secured, labeled flammable liquid, compliant with IMDG regulations. |
| Shipping | N-Hexane is shipped as a hazardous flammable liquid: UN1208, Hexanes, Class 3, Packing Group II. It requires UN-approved packaging, flammable liquid labels, Class 3 placards, and DOT/IATA/IMDG compliance. Keep away from ignition sources, oxidizers, and ensure proper ventilation. |
| Storage | Store n-hexane in a cool, dry, well-ventilated, fire-resistant area away from heat, sparks, flames, and strong oxidizers. Keep containers tightly closed, correctly labeled, grounded, and bonded. Use approved flammable-liquid storage cabinets or safety cans. Protect from direct sunlight and static electricity; maintain appropriate temperature and ventilation, and follow local regulations and SDS requirements. Never store near incompatible materials. |
| Shelf Life | N-Hexane shelf life is typically 5 years when stored sealed in a cool, dry, well-ventilated place away from heat and ignition sources. |
In continuous soybean processing lines rated above 4,000 t/day, n-hexane enters a countercurrent extractor after flaking to 0.25–0.35 mm and expansion at 105–120°C. The expanded collets are extracted at 55–60°C with a solvent-to-flake mass ratio maintained between 1.0:1 and 2.0:1. Miscella leaving the extractor contains 25–35 wt% oil and is routed through hydrocyclones, a rising-film evaporator, and a two-stage oil stripper. The desolventizer-toaster operates with countercurrent steam at 100–110°C, indirect steam up to 120–140°C, and meal discharge moisture of 12–18%. Under-stripping leaves residual n-hexane in meal above 500 mg/kg, while over-heating lowers protein dispersibility index below 40%. The refined oil stripper is held at 200–400 mbar and 110–120°C, reducing residual n-hexane to the EU Directive 2009/32/EC limit of 1 mg/kg in fats and oils. Commercial extraction hexane in US food-processing applications is controlled under 21 CFR 172.884 odorless light petroleum hydrocarbon specifications. Well-maintained mineral oil absorption systems limit hexane loss to 0.5–1.5 L per tonne of seed; flange leaks and rotary valves account for the dominant fugitive fraction. Terminal outputs are crude soybean oil, defatted soybean meal with 47–49% protein, and crude lecithin.
| Process stage | Operating variable | Numeric range |
|---|---|---|
| Extractor | Solvent-to-flake mass ratio | 1.0:1–2.0:1 |
| Miscella concentration | Oil content | 25–35 wt% |
| Desolventizer-toaster | Meal discharge temperature | 100–110°C |
| Oil stripper | Vacuum and target residual | 200–400 mbar; 1 mg/kg |
Botanical extraction campaigns that target heat-labile carotenoids and pungent oleoresins use n-hexane in fixed-bed percolators rather than immersion extractors. Dried paprika or black pepper is ground to 20–30 mesh, pre-dried to moisture below 8%, and packed into extraction vessels. Solvent-to-feed ratios ranging from 6:1 to 10:1 v/w are applied across multiple stages at 50–55°C for 4–6 h per batch. The resulting miscella is concentrated in a wiped-film evaporator at 50–60°C under 150–200 mbar, then transferred to a vacuum stripper below 50 mbar. If stripping temperature exceeds 60°C, capsanthin isomers in paprika oleoresin degrade measurably; if vacuum is insufficient, the viscous oleoresin traps n-hexane in a glassy matrix. Residual n-hexane in the final oleoresin is quantified by headspace gas chromatography with flame ionisation detection at a quantification limit of 0.1 mg/kg. EU Directive 2009/32/EC governs hexane use for production of food flavourings and extracts. Spent botanical marc is desolventised with live steam at 95–105°C, producing a spent solids fraction with residual n-hexane below 500 mg/kg. Terminal products include paprika oleoresin, black pepper oleoresin, capsicum extract, and natural food colourants.
Residual n-hexane control in oral solid dosage forms is governed by ICH Q3C, which assigns n-hexane to Class 2 with a permitted daily exposure of 2.9 mg/day. The default daily intake of 10 g translates to a concentration limit of 290 ppm in a finished drug product. In phytosterol purification, tall oil pitch is extracted with n-hexane at a solvent-to-feed ratio of 5:1 to 8:1 v/w. The extract is chilled to 0–5°C to crystallise phytosterols, and the mother liquor is returned to the extraction circuit. In vitamin purification, n-hexane selectively extracts fat-soluble vitamin fractions from fermentation broth concentrates after pH adjustment. The extract is concentrated in a wiped-film evaporator at 45–55°C, followed by rotary vacuum drying at 30–40°C and 5–20 mbar. n-Hexane is also used as a non-solvent to precipitate poorly water-soluble APIs from ethyl acetate or dichloromethane mother liquors. The Class 2 limit imposes an operational boundary: n-hexane cannot enter terminal purification without a validated recovery step because a 10 g daily dose would exceed 2.9 mg/day at residual levels above 290 ppm. USP <467> Procedure A and Ph.Eur. chapter 5.4 provide the headspace gas chromatographic methods for release testing.
| Control parameter | n-Hexane limit | Reference method |
|---|---|---|
| Permitted daily exposure | 2.9 mg/day | ICH Q3C |
| Concentration limit | 290 ppm | ICH Q3C |
| Release testing | 290 ppm | USP <467> Procedure A |
Once n-hexane enters a slurry loop reactor, water and oxygen impurities dominate catalyst response. Polymer-grade n-hexane is therefore controlled to water below 1 ppm, oxygen below 0.5 ppm, sulfur below 1 ppm, and n-hexane content above 95 wt%, with distillation range specified by ASTM D1836. The diluent is injected into a loop reactor at 60–90°C and 35–45 bar. Slurry solids are held at 25–40 wt% and axial flow velocity is maintained at 6–10 m/s to prevent polymer particle settling and local overheating. Hydrogen is the primary molecular weight modifier; n-hexane itself acts as a weak chain-transfer agent, so its concentration is held within a narrow band to avoid broadening the molecular weight distribution. The diluent mass flow is adjusted to maintain slurry density in the 560–620 kg/m³ range rather than fixed to a single feed ratio. The slurry is flashed through a pressure letdown valve into a cyclone separator, where n-hexane is recovered, condensed, dried over molecular sieves, and recycled. Residual n-hexane in the resulting polyethylene powder is typically below 500 ppm before extrusion pelletising. FDA 21 CFR 177.1520 applies to olefin polymers intended for food contact. Terminal products are high-density polyethylene and linear low-density polyethylene pellets used in blow moulding, cast film, and pipe extrusion.
On a solventborne pressure-sensitive adhesive coating line, the first drying zone is set at 60–70°C, the second at 75–85°C, and the final zone at 90–100°C. n-Hexane is combined with toluene or acetone in a rubber-based adhesive solution at 35–45% solids, with n-hexane comprising 40–60 wt% of the solvent blend. The blend is slot-die coated onto silicone release liner at web speeds of 80–150 m/min and dry coat weights of 15–35 g/m². Because n-hexane has a flash point of -22°C by ASTM D56 and a lower explosive limit of 1.1 vol%, oven ventilation is interlocked to reduce solvent feed when vapour concentration reaches 25% LEL. Exhaust streams are ducted to carbon adsorption beds with 95–98% recovery efficiency. ATEX 2014/34/EU zone classification follows EN 60079-10-1. Worker exposure is constrained by an ACGIH TLV of 50 ppm, a NIOSH REL of 50 ppm, and an OSHA PEL of 500 ppm. Humidity above 70% RH changes evaporative cooling and solvent vapour density, requiring zone ventilation recalculation. Terminal products are transfer tapes, label stock, and masking tapes.
Laboratories reporting oil and grease under a Clean Water Act discharge permit use n-hexane as the extraction solvent specified in US EPA Method 1664B. A 1 L wastewater sample is acidified to pH <2 and extracted with two successive 20 mL portions of n-hexane. The combined extract is dried over anhydrous sodium sulfate, the solvent is distilled, and the residue is desiccated to constant mass. The same solvent is referenced in ISO 9377-2:2000 for hydrocarbon oil index determination by gas chromatography. The method does not distinguish petroleum hydrocarbons from natural lipids; without silica gel treatment, naturally occurring fatty acids co-extract and bias the gravimetric result high. Laboratories must verify that the n-hexane residue after evaporation is below 1 mg/L before sample extraction. Terminal output is a regulatory discharge monitoring report submitted under an NPDES permit, where n-hexane extractable material is reported in mg/L.
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n-Hexane is the straight-chain C6 aliphatic solvent having CAS number 110-54-3, the condensed formula CH3(CH2)4CH3, and a relative molecular mass of 86.18 g/mol. At 20 °C and 101.3 kPa, the liquid density is 0.659 g/mL, the vapor pressure is 17.6 kPa, and the refractive index is 1.3749. The normal boiling point is 68.7 °C; the freezing point is -95.3 °C. The closed-cup flash point is -22 °C, the autoignition temperature is 225 °C, and the flammable range in air is 1.1 vol% to 7.5 vol%. Water solubility at ambient temperature is below 10 mg/L; the material is miscible with ethanol, diethyl ether, chloroform, and most liquid aliphatic and aromatic hydrocarbon streams. Commercial n-hexane is a clear, colourless liquid with a mild gasoline-like odour; the ACGIH 8-hour threshold limit value is 50 ppm, and the OSHA 8-hour permissible exposure limit is 500 ppm. Purchasing documents often distinguish pure n-hexane from commercial mixed hexanes, which may contain 45%–60% n-hexane alongside 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, and 2,3-dimethylbutane.
Supply designations include rectified, synthesis, ACS reagent, and high-purity or HPLC n-hexane. Each designation is controlled by a certificate of analysis that bounds purity and low-level impurities rather than by a single universal specification. A rectified grade is commonly specified at 95.0% minimum n-hexane by gas chromatography, while a synthesis grade is commonly specified at 99.0% minimum and a high-purity grade at 99.5% minimum. Boiling range is tested by ASTM D1078 or ASTM D86; density is tested by ASTM D4052; flash point is reported by ASTM D56; water is measured by ASTM D6304; sulfur is measured by ASTM D5453; and non-volatile residue is measured by ASTM D1353. Benzene concentration is normally restricted below 5 mg/kg in pure n-hexane and below 10 mg/kg in rectified extraction material. Commercial mixed hexane for oilseed extraction is covered by ASTM D1836, which controls appearance, sulfur, benzene, and distillation, but it does not require a single n-hexane purity and is therefore not interchangeable with pure n-hexane for pharmaceutical or polymer applications.
| Supply category | n-Hexane mass fraction | Boiling range | Benzene max | Sulfur max | Water max | Residue max |
|---|---|---|---|---|---|---|
| Rectified/technical grade | ≥95.0% | 68.0–70.0 °C | 10 mg/kg | 5 mg/kg | 100 mg/kg | 5 mg/kg |
| Synthesis/polymer grade | ≥99.0% | 68.0–69.0 °C | 5 mg/kg | 1 mg/kg | 10 mg/kg | 1 mg/kg |
| ACS reagent grade | ≥99.5% | 68.5–69.0 °C | 1 mg/kg | 1 mg/kg | 50 mg/kg | 1 mg/kg |
| HPLC/high-purity grade | ≥99.5% | 68.5–69.0 °C | 1 mg/kg | 0.5 mg/kg | 20 mg/kg | 0.5 mg/kg |
Continuous oilseed extraction lines use n-hexane in countercurrent belt, chain, or rotary extractors at a solvent-to-flake mass ratio near 0.8:1 to 1.2:1 and an extraction temperature of 50–60 °C. The resulting miscella concentration generally reaches 25–35% oil before entering the first-stage rising-film evaporator. After miscella distillation and steam stripping, residual solvent in refined edible oil is reduced to meet the European Union extraction solvent limit of 1 mg/kg in oils and fats under Directive 2009/32/EC. Desolventized meal exits the toaster at 100–110 °C and must be cooled below 35 °C before storage to prevent hexane condensation and agglomeration. In US hop extraction, 21 CFR 173.270 authorizes n-hexane with a residue not exceeding 25 mg/kg in modified hop extract. The narrower boiling range of pure n-hexane reduces heavy solvent carry-over in the oil; the limitation is the higher vapor pressure and lower occupational exposure threshold, which require closed-loop vent recovery to activated carbon or mineral oil absorption.
Wax and phospholipid handling in extraction plants is sensitive to solvent composition. When the n-hexane fraction falls below 60% in mixed hexane feed, isohexane and branched C6 components lower the solvent solubility parameter and may change the cloud point of crystallized wax by 2–3 °C during winterization. Heat exchangers in the miscella evaporation section can develop fouling when phospholipid complexes are carried over from flaked seed; the fouling layer is typically controlled by dosing water to hydrate gums before final stripping. Published data for specific oilseed varieties and extraction durations is limited, so process validation is conducted at line scale with solvent composition monitoring by on-line density and distillation analysis.
n-Hexane is used as a process solvent in low-temperature crystallization because its normal boiling point of 68.7 °C is approximately 30 °C lower than that of n-heptane at 98.4 °C. This permits solvent removal by vacuum distillation below 60 °C in pharmaceutical dryers, but it narrows the operating range against the -22 °C flash point. The ICH Q3C residual solvent classification is a controlling variable: n-hexane is a Class 2 solvent with a permitted daily exposure of 2.9 mg/day and a concentration limit of 290 ppm, while n-heptane is a Class 3 solvent with a default concentration limit of 5000 ppm. Therefore, a process switch from n-heptane to n-hexane requires revalidation of drying, headspace analysis, and batch documentation under ICH Q3C. In polyolefin production, a high-purity n-hexane stream serves as a carrier or diluent for Ziegler-Natta and metallocene catalysts. Reactor feed is dried over 3A or 4A molecular sieves and blanketed with nitrogen to maintain water below 10 mg/kg by ASTM D6304 and oxygen below 1 mg/kg by on-line analyzer. A shift from n-heptane to n-hexane increases pump volumetric throughput at equal temperature, but requires increased condenser capacity because of the 17.6 kPa vapor pressure at 20 °C; published data for this specific configuration is limited.
Adhesive and rubber contact cement formulations use n-hexane as a fast-evaporating diluent in neoprene and styrene-butadiene systems. The drying time of a 200 µm wet film at 23 °C is shorter than with n-heptane, but the lower flash point imposes electrical classification on coating lines. High-shear dispersion equipment with local exhaust is required; batch-to-batch viscosity can rise when low-boiling isohexane impurities in reclaimed solvent exceed 5%. Published technical data for this specific rework and reclaimed-solvent configuration is limited.
Analytical methods for oil and grease in water and soil use n-hexane because the extraction solvent must have a defined boiling range and low extractable residue. EPA Method 1664B specifies n-hexane for hexane extractable material; the method requires a minimum n-hexane content of 85% and a boiling point range of 60–70 °C to limit background interferences. In normal-phase HPLC, high-purity n-hexane is blended with ethyl acetate, isopropanol, or methyl tert-butyl ether; the low UV absorbance of HPLC-grade material at 200 nm reduces baseline drift in diode-array detection. In gravimetric Soxhlet extraction, the low non-volatile residue specification of 1 mg/kg or lower is critical because residual material is weighed. n-Hexane is also used in purification of triglycerides, sterols, and tocopherol concentrates by crystallization; the saturated straight-chain backbone produces a narrower elution window and lower solvent hold-up in rotary evaporators than petroleum ether fractions.
n-Hexane is selected over other low-boiling hydrocarbons when a narrow distillation range and straight-chain geometry are required. Commercial mixed hexanes differ in composition and therefore have a wider distillation envelope; they cannot be treated as pure n-hexane in hydrolysis reactions or toxicological assessments. n-Heptane has a higher boiling point of 98.4 °C and a higher flash point of -4 °C, which makes it easier to handle in open process vessels, but its thermal load is higher during solvent recovery. Cyclohexane has a boiling point of 80.7 °C and a closed-ring structure; it is preferred when higher density and a different solvent power are needed in resin systems. Isohexane streams, principally 2-methylpentane, boil near 60 °C and evaporate more rapidly, which can decrease drying time but increases vapor loss and colder storage requirements. n-Pentane boils at 36.1 °C and is used as a blowing agent and extraction solvent where very low temperature evaporation is required, but its flash point of -49 °C makes room-temperature handling more hazardous. Petroleum ether is a mixture without a single CAS number; its boiling range can be 30–60 °C or 60–80 °C, and its composition changes between suppliers, making reproducibility in validated methods weaker than with pure n-hexane.
| Solvent | CAS | Boiling point | Closed-cup flash point | ICH Q3C classification | Main industrial distinction |
|---|---|---|---|---|---|
| n-Hexane | 110-54-3 | 68.7 °C | -22 °C | Class 2, 2.9 mg/day | Narrow-cut straight-chain extraction and chromatography |
| n-Heptane | 142-82-5 | 98.4 °C | -4 °C | Class 3 | Higher-temperature recovery, lower vapor pressure |
| Cyclohexane | 110-82-7 | 80.7 °C | -18 °C | Class 2 | Cyclic aliphatic solvent for resin and nylon systems |
| Isohexane, 2-methylpentane | 107-83-5 | 60.3 °C | -32 °C | Not assigned in ICH Q3C | Faster drying but higher vapor loss |
| n-Pentane | 109-66-0 | 36.1 °C | -49 °C | Not assigned in ICH Q3C | Very low boiling extraction and blowing agent |
| Petroleum ether | Mixture, 8032-32-4 or 64742-49-0 | 30–60 °C or 60–80 °C | Below -40 °C, variable | Not applicable as mixture | Variable composition, lower reproducibility |
Storage and transfer of n-hexane require grounding and inerting. Tanks are blanketed with nitrogen, and transfer lines are grounded because the liquid has a low electrical conductivity and can develop static charges at high flow velocities. Centrifugal transfer pumps use double mechanical seals or sealless magnetic-drive designs to control fugitive emissions. Dry carbon steel is suitable for closed storage; wet n-hexane can produce water-layer corrosion, so high-purity stainless steel or lined tanks are used for water-sensitive grades. The solvent should be stored away from strong oxidizers, chlorine, and concentrated nitric acid. Personnel exposure is controlled by closed-loop sampling, continuous lower explosive limit monitoring, and respiratory protection when the 50 ppm ACGIH TLV is likely to be exceeded. The high vapor pressure and low autoignition temperature mean that open containers must not be used in heated process areas.
