Hexane, n-Hexane, 110-54-3, 92112-69-1

Hexane, n-Hexane, 110-54-3, 92112-69-1

HEXANE

Hexane / n-Hexane / OXFORD / MARQUIS TEST KIT
CAS Number: 110-54-3; 92112-69-1
EC Number: 203-777-6

1. PRODUCT IDENTIFICATION AND CHEMICAL IDENTITY

Hexane is a straight-chain saturated aliphatic hydrocarbon belonging to the alkane family. It is obtained by cracking and fractionation of crude oil and is one of the main components of petroleum ether and naphtha. At room temperature, it appears as a colorless, transparent liquid with a slight oil-like odor. It is highly volatile, and its vapor is heavier than air, which can form explosive mixtures with air at concentrations between 1.0-8.1% by volume. Hexane is a naturally occurring hydrocarbon in petroleum and one of the most widely used non-polar organic solvents in industrial applications. It has excellent solvent properties for oils, fats, and many organic compounds, making it indispensable in extraction processes, cleaning applications, and organic synthesis. There are five isomers of hexane: n-hexane, 2-methylpentane (isohexane), 3-methylpentane, 2,2-dimethylbutane (neohexane), and 2,3-dimethylbutane. The linear compound is n-hexane, CH₃(CH₂)₄CH₃, which is the primary subject of this document.

2. PHYSICAL AND CHEMICAL PROPERTIES

Hexane is a colorless, volatile liquid with a mild, gasoline-like odor detectable at concentrations of 65 to 248 ppm. It has a density of 0.659 g/mL at 25°C, making it lighter than water, and a specific gravity of 0.660 (20/4°C). The melting point is exceptionally low at -95°C, while the boiling point is 68.95°C, indicating high volatility. The flash point is -1.1°C (30°F), classifying it as a highly flammable liquid with a very low flash point. Vapor pressure at 20°C is 40 mm Hg, and vapor density is 3.5 (air=1), meaning its vapor is approximately 3.5 times heavier than air and may accumulate in low-lying areas. Hexane is practically insoluble in water but very soluble in ethanol, ethyl ether, chloroform, ketones, and other organic solvents, making it an excellent non-polar solvent for a wide range of organic compounds. The Henry's Law constant increases with temperature (0.238 at 10°C to 1.56 at 30°C), indicating increased volatilization at higher temperatures. The LogP value of 4 indicates moderate lipophilicity, which contributes to its fat solubility and potential bioaccumulation. The relative polarity of 0.009 confirms its highly non-polar nature.

3. STABILITY, REACTIVITY AND STORAGE

Hexane is stable under normal storage conditions but is highly flammable and readily forms explosive mixtures with air. It is incompatible with strong oxidizing agents, chlorine, fluorine, and magnesium perchlorate, with which it can react violently. Storage should be at temperatures between +5°C and +30°C in a cool, well-ventilated area, away from heat, sparks, open flames, and other ignition sources. The low flash point of -1.1°C requires special precautions to prevent fire and explosion hazards. Static electricity accumulation can occur during handling and transfer operations, requiring proper grounding and bonding of all equipment. Explosion-proof electrical equipment and ventilation systems should be used in areas where hexane is stored or handled. Containers should be kept tightly closed when not in use to prevent vapor release and contamination. The product is sensitive to light and should be stored in opaque or amber containers for long-term storage to prevent degradation and peroxide formation.

4. CHEMICAL PROPERTIES AND REACTIONS

Hexane, as a saturated alkane, undergoes characteristic reactions typical of alkanes. Its chemical behavior is dominated by its non-polar nature and the relative inertness of C-C and C-H bonds under normal conditions.

Oxidation Reaction:

Hexane is extremely flammable and its vapor forms explosive mixtures with air. It is highly flammable and explosive when exposed to open flame and high heat. A strong reaction occurs when in contact with oxidizers and may even cause combustion. In a fire scene, a heated container is at risk of explosion. Its vapor is heavier than air and can diffuse to a considerable distance at ground level, leading to flashback ignition when encountering an open flame. The combustion products are carbon dioxide, water, and carbon monoxide (carbon monoxide is produced during incomplete combustion).

The chemical equation for complete combustion of hexane is:

2 C₆H₁₄ + 19 O₂ → 12 CO₂ + 14 H₂O (condition: ignition)

Substitution Reaction:

Like other alkanes, hexane can undergo substitution reactions with halogens (F, Cl, Br, I), producing various substituted compounds. The reaction with halogens proceeds via free-radical mechanism under UV light or heat:

C₆H₁₄ + Cl₂ → C₆H₁₃Cl + HCl

Therefore, hexane must be stored away from halogens (e.g., fluorine, chlorine, bromine, iodine) to prevent unintended reactions. The chlorination of hexane produces a mixture of mono-, di-, and polychlorinated products, which are industrially important intermediates but also present environmental and health concerns.

Isomerization:

n-Hexane can be isomerized to branched-chain isomers (2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane) under catalytic conditions (typically using aluminum chloride or platinum-based catalysts at elevated temperatures). This reaction is important in the petroleum refining industry to increase the octane number of gasoline fractions.

Dehydrogenation:

Under high temperature and catalytic conditions (typically platinum or chromium oxide catalysts), n-hexane can be dehydrogenated to hexenes and other unsaturated hydrocarbons, which are valuable intermediates for petrochemical synthesis.

Cracking:

Under high temperature conditions (typically >400°C) and sometimes in the presence of catalysts, n-hexane can undergo thermal cracking to produce smaller hydrocarbons such as ethylene, propylene, butenes, and other light olefins.

Peroxide Formation:

Like other ethers and alkanes, hexane can form peroxides upon prolonged exposure to air and light. Peroxides are potentially explosive compounds that can cause violent reactions. Therefore, hexane should be stored away from light and air, and peroxides should be tested before distillation or evaporation.

5. SPECIFICATIONS AND QUALITY CONTROL

Hexane is available in various grades depending on the application. Industrial grades typically have a minimum purity of 95%, while high purity grades (for HPLC, spectrophotometry, and pharmaceutical applications) have a minimum purity of 99%. The product should appear as a clear, colorless liquid free from suspended matter and particulates. UV cut-off is an important specification for spectrophotometric applications, with maximum absorbances specified at 200 nm (≤0.70), 225 nm (≤0.10), and 250 nm (≤0.01). Water content is strictly controlled to a maximum of 0.02% by Karl Fischer titration, as moisture can interfere with many applications, particularly in Grignard reactions and other water-sensitive processes. Benzene content is typically maintained below 0.1%, often less than 0.05%, to minimize health hazards associated with benzene exposure. Sulfur content is kept below 1 ppm for applications sensitive to sulfur-containing compounds.

6. ISOMERS OF HEXANE

Hexane has five structural isomers, each with different physical properties and industrial applications. All are colorless, volatile, flammable liquid alkanes with weak, specific odors.

The linear compound is n-hexane, CH₃(CH₂)₄CH₃. The branched isomers (isohexane, 3-methylpentane, neohexane, and diisopropyl) have lower boiling points and higher octane numbers compared to n-hexane. The branched isomers are often used as components in gasoline blending to achieve desired octane ratings, while n-hexane is primarily used as a solvent and extraction agent. The different physical properties of these isomers require careful separation and purification processes in industrial production. The presence of branched isomers in commercial hexane products can affect solvent properties and performance in specific applications.

7. PRODUCTION METHODS

Hexane is primarily produced by fractionation of petroleum fractions, particularly from straight-run gasoline, platinum reforming raffinate, or wet natural gas. The content of n-hexane in these fractions is approximately 1-15%.

The industrial process for n-hexane production typically involves the following steps:

1. Feedstock Preparation: Raffinate oil (C6-C7 fraction) from catalytic reforming units is used as the primary raw material.

2. Fractional Distillation: The raffinate oil is subjected to multiple distillation columns to separate the C6 fraction containing hexane isomers.

3. De-benzene Treatment: The C6 fraction is hydrogenated using specialized catalysts (such as 0501-type) to remove benzene and other unsaturated hydrocarbons by converting them to saturated compounds.

4. Final Purification: Additional distillation steps are used to concentrate n-hexane and separate it from branched isomers.

5. Quality Control: The final product is analyzed for purity, water content, benzene content, and other quality parameters before packaging.

Alternative methods such as adsorption separation using molecular sieves are also employed in some regions, particularly in the United States. These methods can achieve higher purity n-hexane but are more capital-intensive.

8. APPLICATIONS AND INDUSTRIAL USES

Hexane is one of the most versatile organic solvents and finds extensive use across multiple industries. Its excellent dissolving power for oils, fats, and many organic compounds makes it indispensable in numerous applications.

8.1. Solvent Applications

8.2. Cleaning and Degreasing Applications

8.3. Chemical and Manufacturing Applications

8.4. Other Applications

9. HEALTH EFFECTS AND TOXICOLOGY

Hexane exhibits low acute toxicity but significant chronic health effects, particularly on the peripheral nervous system. Its lipophilic nature allows it to accumulate in fatty tissues and the nervous system.

9.1. Toxicological Data

9.2. Mechanism of Toxicity

The toxicity of n-hexane is primarily mediated by its metabolites. Part of n-hexane is metabolized in the body to produce 2-hexanone (methyl butyl ketone) and 2,5-hexanedione. These metabolites can interfere with the axonal transport of substances within nerve fibers, leading to nerve damage characterized by:

• Peripheral Neuropathy: Distal axonopathy affecting sensory and motor neurons, primarily in the lower extremities.

• Central Nervous System Effects: Mild inhibitory effects on the central nervous system causing dizziness, nausea, and headaches.

• Myelin Damage: Damage to the myelin sheath of nerves, leading to slowed nerve conduction velocity.

9.3. Clinical Manifestations

Acute Exposure Effects:

Chronic Exposure Effects:

Long-term occupational exposure to n-hexane (≥50 ppm) can cause chronic n-hexane poisoning, a systemic disease mainly characterized by nervous system damage. Industrial hexane often contains benzene, toluene, and other organic compounds, increasing the health risk. After entering the human body, n-hexane primarily affects the energy metabolism of the central nervous system, causing nerve fiber degeneration, leading to neurasthenia syndrome and autonomic nerve dysfunction. The main clinical manifestations include:

• Distal limb loss of touch, pain sensation, and temperature sensation

• Decreased muscle strength or limb paralysis

• Decreased nerve conduction velocity (electromyography findings)

• Axonal degeneration with demyelination (pathological findings)

Most symptoms disappear within a few months if exposure is stopped. However, in severe cases, patients may experience permanent neurological damage and lifelong disability. The condition may continue to worsen for several months after removal from exposure due to ongoing metabolic effects.

9.4. Interaction with Other Substances

9.5. Isomer Toxicity Comparison

10. OCCUPATIONAL EXPOSURE AND INDUSTRIAL SAFETY

10.1. Occupational Exposure Limits

10.2. Occupational Health Risks

n-Hexane Poisoning Epidemics:

Chronic n-hexane poisoning has been a significant occupational health problem in many countries:

• 1957: Italy first reported toxic peripheral nerve damage cases in the shoe industry.

• 1968: Japan reported nearly 100 workers with peripheral nerve damage in plastic sandal production.

• 1980s-Present: China has experienced almost annual outbreaks of n-hexane chronic poisoning, particularly in coastal areas in shoe production, electronic component manufacturing, and luggage production industries.

China's Experience:

In recent years, n-hexane used as a diluent for adhesive production or as an organic detergent has become the main culprit in group occupational n-hexane poisoning events in China. Cases have been reported in:

• Shoe manufacturing plants

• Electronic component factories

• Luggage production facilities

• Printing and packaging industries

• Furniture manufacturing

Prevention Measures:

• Substitution: Replace n-hexane with less toxic solvents (e.g., branched hexane isomers, other hydrocarbon solvents).

• Engineering Controls: Use local exhaust ventilation, closed systems, and automated processes.

• Personal Protective Equipment: Use appropriate PPE including chemical-resistant gloves, protective clothing, and respiratory protection (organic vapor cartridges).

• Medical Surveillance: Regular medical examinations including neurological assessments and nerve conduction studies.

• Training: Educate workers about the hazards of n-hexane and proper handling procedures.

• Monitoring: Regular air monitoring to ensure exposure levels are below occupational limits.

11. FIRST AID MEASURES

12. FIREFIGHTING MEASURES

13. ACCIDENTAL RELEASE MEASURES

14. ENVIRONMENTAL INFORMATION

15. REGULATORY INFORMATION

Regulatory Status:

16. OTHER NAMES AND DATABASE IDENTIFIERS

Database Identifiers:

17. SAFETY DATA (GHS CLASSIFICATION)

Signal Word: DANGER

Hazard Statements:

18. PRECAUTIONARY STATEMENTS (P-CODES)

19. DOWNSTREAM AND UPSTREAM PRODUCTS

19.1. Raw Materials (Upstream)

19.2. Derivative Products (Downstream)

20. SUMMARY AND CRITICAL WARNINGS

SUMMARY:

Hexane (n-Hexane, C₆H₁₄, CAS 110-54-3) is a straight-chain saturated aliphatic hydrocarbon obtained by fractionation of crude oil. It is a colorless, volatile liquid with a mild gasoline-like odor, molecular weight of 86.18 g/mol, density of 0.659 g/mL, boiling point of 68.95°C, and flash point of -1.1°C. It is highly flammable and readily forms explosive mixtures with air (1.0-8.1% by volume). It is practically insoluble in water but very soluble in ethanol, ether, chloroform, and other organic solvents. Hexane is one of the most widely used non-polar organic solvents in industrial applications. The largest applications include edible oil extraction, rubber processing, pharmaceutical extraction, electronics cleaning, leather finishing, textile cleaning, and paint manufacturing. It is also used as a solvent in organic synthesis, propylene polymerization, and as a component in high-octane fuels. From a health perspective, n-hexane exhibits low acute toxicity but significant chronic neurotoxicity, causing peripheral neuropathy through its metabolites (2-hexanone and 2,5-hexanedione). Chronic occupational exposure can cause symmetrical distal sensory and motor neuropathy, primarily affecting the lower extremities. It is classified as a highly flammable liquid with hazards of aspiration, skin irritation, narcotic effects, and reproductive toxicity. It is also very toxic to aquatic organisms with long-lasting environmental effects. The maximum allowable concentration limits vary by country: 50 ppm (ACGIH), 500 ppm (OSHA), and 100 ppm (Japan).

Key Properties:

Major Application Areas:

Toxicological Summary:

Key Safety Points:

• HIGHLY FLAMMABLE: Flash point -1.1°C; keep away from all ignition sources

• EXPLOSIVE MIXTURES: Forms explosive mixtures with air (1.0-8.1% by volume); use explosion-proof equipment

• NEUROTOXIN: Chronic exposure causes peripheral neuropathy; monitor exposure limits strictly

• ASPIRATION HAZARD: May be fatal if swallowed and enters airways; do NOT induce vomiting

• REPRODUCTIVE TOXICITY: Suspected of damaging fertility

• ENVIRONMENTAL HAZARD: Very toxic to aquatic life with long-lasting effects

• STORAGE: Store below 30°C in cool, well-ventilated area away from ignition sources

• PPE REQUIRED: Chemical-resistant gloves, goggles, protective clothing, respiratory protection if ventilation is inadequate

CRITICAL WARNINGS:

Chronic Neurotoxicity (n-Hexane Poisoning): n-Hexane is the most toxic of the hexane isomers due to its metabolism to neurotoxic metabolites (2-hexanone and 2,5-hexanedione). Chronic occupational exposure to n-Hexane (≥50 ppm) causes symmetrical distal peripheral neuropathy. Clinical manifestations include tingling, numbness, and weakness in the extremities (particularly the lower limbs). Symptoms may progress to foot drop, muscle atrophy, and sensory loss. The condition may worsen for several months after removal from exposure. In severe cases, permanent neurological damage and lifelong disability can result. Mixed exposure to methyl ethyl ketone (MEK) enhances toxicity, while toluene reduces it.

Industrial Incidents: Since the 1980s, China has experienced almost annual outbreaks of n-hexane chronic poisoning, particularly in shoe manufacturing, electronic components, luggage production, and furniture industries. Similar incidents have been reported in Italy (1957), Japan (1968), and other countries. n-Hexane used as a diluent for adhesives or as an organic detergent has been the main cause of group occupational poisoning events.

Flammability and Explosion Risk: With a flash point of -1.1°C, hexane is a highly flammable liquid with a very low flash point. Vapors are heavier than air and may travel considerable distances to ignition sources, causing flashback. Explosive limits range from 1.0-8.1% by volume in air. Static electricity accumulation can cause ignition. Use explosion-proof electrical equipment, proper grounding, and non-sparking tools.

Aspiration Hazard: Hexane presents a significant aspiration hazard. If swallowed, it can enter the lungs and cause chemical pneumonitis, which can be fatal. Do NOT induce vomiting. If ingested, seek immediate medical attention.

Environmental Persistence: Hexane is very toxic to aquatic organisms with long-lasting adverse effects in the aquatic environment. It is moderately mobile in soil, readily evaporates, and undergoes photochemical oxidation in the atmosphere. Prevent entry into drains, sewers, and water bodies.

Occupational Health Monitoring: Workers exposed to n-hexane should undergo regular medical examinations, including neurological assessments and nerve conduction studies. Workplaces should conduct routine air monitoring to ensure exposure levels remain below occupational limits. Workers should be educated about the hazards of hexane and proper handling procedures.

Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. The information provided is based on available data and is believed to be accurate. However, the user is solely responsible for determining the suitability of the product for their specific application and for complying with all applicable regulations and safety requirements. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. Users are responsible for testing the product in their own processes and applications. All local, national, and international regulations must be followed when working with hexane.