n-Hexane

Classification

Flammable liquid, Category 2; Skin irritation, Category 2; Reproductive toxicity, Category 2; STOT single exposure, Category 3 (drowsiness or dizziness); STOT repeated exposure, Category 2 (nervous system); Aspiration hazard, Category 1; Hazardous to the aquatic environment, acute Category 2 and chronic Category 2

Hazard statements

• H225 Highly flammable liquid and vapor.
• H304 May be fatal if swallowed and enters airways.
• H315 Causes skin irritation.
• H336 May cause drowsiness or dizziness.
• H361 Suspected of damaging fertility or the unborn child.
• H373 May cause damage to organs (nervous system) through prolonged or repeated exposure.
• H411 Toxic to aquatic life with long-lasting effects.

Key precautionary statements

• P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
• P240 Ground and bond container and receiving equipment.
• P241 Use explosion-proof electrical, ventilating and lighting equipment.
• P260 Do not breathe vapors.
• P273 Avoid release to the environment.
• P280 Wear protective gloves, protective clothing, eye protection and face protection.
• P301+P310 IF SWALLOWED: Immediately call a POISON CENTER or doctor.
• P331 Do NOT induce vomiting.
• P403+P235 Store in a well-ventilated place. Keep cool.

The OSHA permissible exposure limit for n-hexane is 500 ppm as an 8-hour TWA (Table Z-1). That is ten times higher than current recommendations: NIOSH recommends 50 ppm as a 10-hour TWA and the ACGIH TLV is 50 ppm as an 8-hour TWA. Because the nerve damage builds up over months of exposure, many employers manage to the 50 ppm values rather than the OSHA PEL. The NIOSH IDLH is 1,100 ppm, set at 10% of the lower explosive limit. Skin contact adds to total exposure. State OSHA plans may set different limits.

• Appearance: Colorless, highly volatile liquid
• Odor: Faint, gasoline-like odor
• Molecular weight: 86.2
• Boiling point: 156°F (69°C)
• Freezing point: -139°F (-95°C)
• Flash point: -7°F (-22°C), Class IB flammable liquid
• Autoignition temperature: 437°F (225°C)
• Explosive limits: LEL 1.1%, UEL 7.5%
• Vapor pressure: 124 mmHg
• Specific gravity: 0.66 (floats on water)
• Water solubility: 0.002% (practically insoluble)

Inhalation

Irritates the nose and throat. Short-term exposure causes headache, dizziness, nausea and lightheadedness; very high levels can cause unconsciousness and death.

Skin

Irritates the skin and removes its natural oils, leading to dryness, redness and dermatitis with repeated contact.

Eyes

Irritates the eyes.

Ingestion

If swallowed, the liquid can easily be breathed into the lungs and cause severe chemical pneumonia. Do not induce vomiting; get medical attention immediately.

Target organs

Eyes, skin, respiratory system, central and peripheral nervous systems

Long-term effects

The signature hazard of n-hexane is peripheral neuropathy: repeated exposure over weeks to months can cause numbness, tingling and weakness that starts in the hands and feet, and recovery can be slow. NJDOH recommends nervous system exams before and during work for people with frequent or high exposure, as part of medical surveillance. NJDOH also notes n-hexane may damage the testes. It has not been tested for cancer in animals. Many commercial "hexane" solvents are blends of isomers with different n-hexane content, so check the SDS composition. Like other organic solvents, it also causes short-term drowsiness and dizziness.

Gloves

The New Jersey Department of Health lists nitrile, polyvinyl alcohol (PVA), Silver Shield/4H, Viton, Viton/Butyl and Barrier gloves. A supplier SDS reports more than 8 hours of breakthrough for 0.4 mm nitrile, while thin disposable nitrile (about 0.1 mm) protects only against splashes. See hand protection.

Eyes and face

Chemical splash goggles; add a face shield for large transfers.

Respiratory

Rely on local exhaust ventilation and enclosed processes first. NJDOH advises a supplied-air respirator with a full facepiece in positive-pressure mode above 50 ppm, and SCBA for fires or possible exposure above 1,100 ppm. NIOSH lists only supplied-air and SCBA options for routine use, with organic vapor gas masks for escape. See respiratory protection.

Clothing

Chemical-resistant clothing (for example Tychem F, BR, CSM or TK) where splashing is likely. Remove clothing promptly if wet, because it is flammable, and wash skin when contaminated.

Store in tightly closed containers in a flammable-liquid cabinet or approved flammables area that is cool, well ventilated and out of direct light, away from heat, sparks and flame.

Ground and bond containers during transfer, use non-sparking tools and explosion-proof electrical equipment, and control static. Check for explosive vapor concentrations before entering any confined space where hexane has been used.

Keep away from

• Strong oxidizers (such as peroxides, perchlorates, permanganates, chlorates, nitrates, chlorine, bromine and fluorine)
• Dinitrogen tetroxide and other nitrogen oxides
• Some plastics, rubbers and coatings, which hexane attacks

• Eliminate all ignition sources and ventilate the area.
• Evacuate unprotected people and control entry; vapors are heavier than air and can travel to distant ignition sources.
• Use spark-proof tools and explosion-proof equipment.
• Absorb with dry sand, earth, vermiculite or another inert material and place in sealed containers for disposal.
• Keep out of drains, sewers and waterways; n-hexane is toxic to aquatic life.
• Waste may need to be handled as hazardous waste; check with your state environmental agency or EPA.
• For larger spills, refer to ERG Guide 128.

Suitable extinguishing media

• Dry chemical
• Carbon dioxide (CO₂)
• Alcohol-resistant foam
• Water spray in flooding amounts to cool containers (a solid water stream may spread the fire)

Special hazards

Highly flammable, with a flash point well below room temperature. If the leak cannot be stopped, it may be safer to let the fire burn than to extinguish it and leave a vapor cloud. Vapors are heavier than air, travel along the ground and can flash back. Containers may explode when heated. Fires produce carbon monoxide and carbon dioxide. Firefighters should wear SCBA and full protective gear.

• OSHA Hazard Communication (29 CFR 1910.1200): Hazardous chemical; labels, safety data sheets and worker training required.
• OSHA Flammable Liquids (29 CFR 1910.106): Class IB flammable liquid.
• OSHA Air Contaminants (29 CFR 1910.1000 Table Z-1): 500 ppm TWA.
• CERCLA hazardous substance (40 CFR 302.4): Listed as "Hexane"; reportable quantity 5,000 lb (2,270 kg).
• DOT Hazardous Materials (49 CFR 172.101): UN1208 Hexanes, Class 3, PG II.

• NIOSH Pocket Guide: n-Hexane
• NJ Department of Health Hazardous Substance Fact Sheet: n-Hexane
• Sigma-Aldrich SDS: Hexane (650552)
• 40 CFR 302.4: CERCLA hazardous substances and reportable quantities