Is Cyclohexane Flammable: Combustion & Explosive Hazards

Cyclohexane is used as a chemical intermediate for a variety of industrial products, including solvents for fats, oils, waxes, resins, and synthetic rubbers.

If you are handling this chemical, you may be wondering: is cyclohexane flammable? Or can it reach combustible or even explosive levels?

This guide will uncover the truth about cyclohexane’s fiery potential.

Is Cyclohexane Flammable?

Cyclohexane is a highly flammable liquid and vapor that can easily catch fire. Cyclohexane vapor may cause a flash fire and heating will cause a rise in pressure with a risk of bursting.

Does Cyclohexane Undergo Combustion?

Yes, cyclohexane undergoes combustion when exposed to oxygen and a sufficient heat source. The combustion reaction of cyclohexane is as follows: C6​H12 ​+ 9O2 ​→ 6CO2 ​+ 6H2​O

Cyclohexane in beaker

Is Cyclohexane Explosive?

Cyclohexane is explosive under certain conditions. Cyclohexane can form explosive mixtures with air within the range of 1.3% to 8% by volume. Cyclohexane can also react violently with oxidizing agents, such as nitric acid, perchloric acid, or hydrogen peroxide, and cause explosions.

It is important to store and handle cyclohexane with care and avoid contact with incompatible materials to reduce the risk of explosion.

flash Point of Cyclohexane

The flash point of cyclohexane is -4°F (-20°C). This means that cyclohexane is highly flammable and can easily catch fire even at very low temperatures.

Frequently Asked Questions

What is Cyclohexane?

Cyclohexane is a cycloalkane made of carbon and hydrogen with the molecular formula C6H12. Cyclohexane is a colorless liquid that has a sweet, gasoline-like odor.

Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon. Cyclohexane is also used as a solvent for chemical reactions and in the production of rubber and plastics.

What Class of Flammable Is Cyclohexane?

Cyclohexane is a Class IB flammable liquid, according to the NFPA and OSHA classifications. This means that it has a flash point below 73°F (23°C) and a boiling point at or above 100°F (38°C).

What happens when cyclohexane is heated?

When cyclohexane is heated, it can undergo various chemical reactions depending on the conditions and the presence of other substances. For example, cyclohexane can undergo combustion when exposed to oxygen and a sufficient heat source, producing carbon dioxide and water.

Cyclohexane can also be dehydrogenated to cyclohexene, which is a precursor to many organic compounds. Cyclohexane can also be oxidized to cyclohexanol or cyclohexanone, which are used to make nylon.

What color does cyclohexane burn?

Cyclohexane burns with a clear light yellow flame, producing less soot than cyclohexene, which burns with a dark yellow sooty flame.

What are the dangers of cyclohexane?

Cyclohexane is a highly flammable and toxic substance that can cause serious health and environmental hazards. Cyclohexane can irritate and burn the skin and eyes, and cause drowsiness, dizziness, nausea, vomiting, and unconsciousness if inhaled or ingested.

Additional hazards of cyclohexane include:

  • Damaging the liver and kidneys.
  • Affecting the central nervous system.
  • Form explosive mixtures with air, and react violently with oxidizing agents
  • Contaminate water and soil, and harm aquatic life.

Fire Safety Tips for Cyclohexane

Follow these tips when handling cyclohexane to prevent fires and explosions:

  • Keep away from heat, sparks, open flames, and hot surfaces.
  • Use only non-sparking tools.
  • Use explosion-proof electrical, ventilating, lighting, and equipment.
  • Store in a well-ventilated and cool place. Keep the container tightly closed.
  • Avoid breathing vapors. Wear protective gloves, eye protection, and face protection. Wash skin thoroughly after handling.
  • In case of fire, use dry sand, dry chemical, or alcohol-resistant foam to extinguish. Do not use water or foam, as they may spread the fire.
  • If swallowed, do not induce vomiting. Seek immediate medical attention.
  • If on skin, take off contaminated clothing and rinse with water. Seek medical advice if irritation occurs.
  • If inhaled, remove to fresh air and keep comfortable for breathing. Seek medical attention if feeling unwell.


In conclusion, cyclohexane is highly flammable, with vapors igniting at very low temperatures. When ignited, cyclohexane undergoes combustion, releasing significant heat. Due to its ability to form explosive vapor-air mixtures, proper handling and storage are crucial.