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CHEMINFO Record Number: 248
CCOHS Chemical Name: Isopentane

Pentane (non-specific name)

Chemical Name French: Isopentane
Chemical Name Spanish: Isopentano
CAS Registry Number: 78-78-4
Other CAS Registry Number(s): 68923-44-4
UN/NA Number(s): 1265
RTECS Number(s): EK4430000
EU EINECS/ELINCS Number: 201-142-8
Chemical Family: Saturated aliphatic hydrocarbon / alkane / pentane isomer
Molecular Formula: C5-H12
Structural Formula: (CH3)2-CH-CH2-CH3


Appearance and Odour:
Colourless liquid with a gasoline-like odour.

Odour Threshold:
Not available

Warning Properties:
Insufficient information

Isopentane is one of the chemical forms (isomers) of pentane (C5-H12). It has many similarities (properties and hazards) to other pentanes. Some information in this record is given specifically for isopentane. Much information applies to pentanes in general.

Uses and Occurrences:
Used as a solvent; blowing agent for polystyrene and other polymers; in the synthesis of organic chemicals (eg. chlorinated hydrocarbons); constituent of motor vehicle and aviation fuel.


Colourless liquid, gasoline-like odour. EXTREMELY FLAMMABLE LIQUID AND VAPOUR. Can accumulate static charge. Vapour is heavier than air and may spread long distances. Distant ignition and flashback are possible. Liquid can float on water and may travel to distant locations and/or spread fire. Central nervous system depressant. High vapour concentrations may cause headache, nausea, dizziness, drowsiness, confusion, unconsciousness and death.


Effects of Short-Term (Acute) Exposure

No symptoms were observed following a 10-minute exposure to 5000 ppm of a pentane mixture containing 20.8% isopentane.(11) Based on information for n- pentane, higher concentrations may cause irritation of the nose and throat, coughing, and symptoms of central nervous system depression, including shortness of breath, headache, nausea, drowsiness, confusion, dizziness, and feelings of dullness. Extremely high concentrations may cause numbness, loss of consciousness and possibly death.

Skin Contact:
Liquid may cause mild to moderate skin irritation with evaporative cooling.
In one study using human volunteers, application of 1.5 ml pentane (isomers not specified) for 1 hour on the forearm and on the thigh for 5 hours resulted in painful burning sensations with itching. The pain subsided within 15 minutes after exposure ceased. This study was conducted in 1936 and an occlusive dressing was used. There are no more recent studies reporting irritation available.(12)

Eye Contact:
Liquid may cause temporary eye irritation. The liquid will rapidly evaporate.

Not applicable. Isopentane cannot be swallowed because body temperature is above its boiling point. The liquid will rapidly boil off when it contacts body tissue.

Effects of Long-Term (Chronic) Exposure

No known health effects from long-term exposure.


No specific information. Probably not carcinogenic.

The International Agency for Research on Cancer (IARC) has not evaluated the carcinogenicity of this chemical.

The American Conference of Governmental Industrial Hygienists (ACGIH) has not assigned a carcinogenicity designation to this chemical.

The US National Toxicology Program (NTP) has not listed this chemical in its report on carcinogens.

Teratogenicity and Embryotoxicity:
No information available

Reproductive Toxicity:
No information available

Negative in a short-term bacterial test (Ames Test).(3)

Toxicologically Synergistic Materials:
Isopentane could likely sensitize the heart to the action of epinephrine.(3)

Potential for Accumulation:
Unlikely to accumulate; readily broken down and excreted in the urine.


This product is flammable. Take proper precautions, (e.g. remove any sources of ignition). Remove source of contamination or move victim to fresh air. If breathing has stopped, trained personnel should begin artificial respiration or, if the heart has stopped, cardiopulmonary resuscitation (CPR) immediately. Obtain medical attention immediately.

Skin Contact:
Remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). Gently blot or brush away excess chemical quickly. Wash gently and thoroughly with water and non-abrasive soap for 5 minutes or until the chemical is removed. If irritation persists, obtain medical advice immediately.

Eye Contact:
Quickly and gently blot or brush away excess chemical. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 5 minutes or until the chemical is removed, while holding the eyelid(s) open. Obtain medical advice immediately.

Not applicable. Isopentane cannot be swallowed.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest). Consult a doctor and/or the nearest Poison Control Centre for all exposures except minor instances of inhalation or skin contact. All first aid procedures should be periodically reviewed by a doctor familiar with the material and its conditions of use in the workplace.


Flash Point:
-51 deg C (-60 deg F)

Lower Flammable (Explosive) Limit (LFL/LEL):

Upper Flammable (Explosive) Limit (UFL/UEL):

Autoignition (Ignition) Temperature:
420 deg C (788 deg F)

Sensitivity to Mechanical Impact:
Probably not sensitive. Stable material.

Sensitivity to Static Charge:
Liquid can accumulate static charge by flow or agitation. Vapours can be ignited by static discharge.

Fire Hazard Summary:
Extremely flammable liquid. Can release vapours that form explosive mixtures with air. Vapour is heavier than air and may travel a considerable distance to a source of ignition and flash back to a leak or open container. Liquid can float on water and may travel to distant locations and/or spread fire. Firefighters may enter the area if positive pressure self-contained breathing apparatus (MSHA/NIOSH approved or equivalent) and full Bunker Gear is worn.

Extinguishing Media:
Foam, dry chemical, carbon dioxide. Water may be ineffective.

Fire Fighting Instructions:
Water may be ineffective because it may not cool the material below its flash point. However, water can be applied as a fine spray to absorb heat, keep containers cool and protect exposed material. If a leak or spill has not ignited, use water spray to disperse the vapours and to protect personnel attempting to stop a leak. Water spray may be used to flush spills away from exposures. As in any fire, wear self-contained breathing apparatus (SCBA), pressure-demand, (MSHA/NIOSH approved or equivalent) and Bunker Gear.


NFPA - Health: 1 - Exposure would cause significant irritation, but only minor residual injury.
NFPA - Flammability: 4 - Will rapidly or completely vaporize at atmospheric pressure and normal ambient temperature, or readily disperse in air and burn readily.
NFPA - Instability: 0 - Normally stable, even under fire conditions, and not reactive with water.


Molecular Weight: 72.15

Conversion Factor:
1 ppm = 2.95 mg/m3; 1 mg/m3 = 0.34 ppm at 25 deg C

Physical State: Liquid
Melting Point: FREEZING POINT: -160 deg C (-256 deg F)
Boiling Point: 27.8 deg C (82 deg F) (1)
Relative Density (Specific Gravity): 0.62 at 20 deg C (water = 1) (2)
Solubility in Water: Insoluble
Solubility in Other Liquids: Soluble in alcohol and ether
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = 3.2-3.3 (3)
pH Value: Not applicable
Vapour Density: 2.5 (air = 1) (2)
Vapour Pressure: 595 mm Hg at 21 deg C (2)
Saturation Vapour Concentration: About 800000 ppm at 21 deg C (calc.)
Evaporation Rate: Not available
Critical Temperature: 187 deg C (369 deg F)


Normally stable

Hazardous Polymerization:
Does not occur

Incompatibility - Materials to Avoid:

NOTE: Chemical reactions that could result in a hazardous situation (e.g. generation of flammable or toxic chemicals, fire or detonation) are listed here. Many of these reactions can be done safely if specific control measures (e.g. cooling of the reaction) are in place. Although not intended to be complete, an overview of important reactions involving common chemicals is provided to assist in the development of safe work practices.

STRONG OXIDIZING AGENTS (e.g. peroxides, nitrates and perchlorates) - Can increase risk of fire and explosion.

Hazardous Decomposition Products:

Conditions to Avoid:
Static discharge, sparks, open flames and other ignition sources

Corrosivity to Metals:
Not corrosive


LC50 (mouse): 140,000 ppm (2-hour exposure) (3, unconfirmed)

Effects of Short-Term (Acute) Exposure:

At 150,000-170,000 ppm isopentane was lethal to dogs.(3) At 90,000 ppm, a 12-minute exposure caused light anesthesia in mice, while 110,000-120,000 ppm caused anesthesia within 4 minutes with complete loss of posture within 10 minutes.(3) Exposure to 120,000 pm induced light anesthesia in dogs.(3) Exposure of dogs to 100,000-250,000 ppm sensitized the heart to the action of epinephrine, causing irregular heatbeat (arrhythmias).(3)


Selected Bibliography:
(1) Documentation of the threshold limit values and biological exposure indices. 6th ed. ACGIH, 1991. p. 1185-1186
(2) Cavender, F. Aliphatic hydrocarbons. In: Patty's industrial hygiene and toxicology. 4th rev. ed. Vol. 2B. Edited by G.D. Clayton et al. John Wiley & Sons, 1994. p. 1221-1266
(3) Ethel Browning's toxicity and metabolism : vol. 1 : hydrocarbons. 2nd ed. Elsevier Science Publishers, 1987. p. 287-290
(4) Handling chemicals safely. Dutch Association of Safety Experts, 1980. p. 572
(5) Hazardous chemicals data book. 2nd ed. Noyes Data Corporation, 1986. p. 599
(6) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(7) Final report of the safety assessment of isobutane, isopentane, n-butane, and propane. Journal of the American College of Toxicology. Vol. 1, no. 4 (1982). p. 127-142
(8) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 325
(9) NIOSH pocket guide to chemical hazards. NIOSH, June 1994. p. 244-245
(10) European Communities. Commission Directive 98/98/EC. December 15, 1998
(11) Patty, F.A. and Yant, W.P. Report of Investigations: Odor intensity and symptoms produced by commercial propane, butane, pentane, hexane and heptane vapor. U.S. Bureau of Mines Report Invest. No. 2979. U.S. Dept. of Commerce, Washington, D.C. (1929)
(12) Oettel, H. Effect of Organic Liquids on the Skin. Arch fuer Experimentelle Pathologie. Vol. 83 (1936). p. 641-696

Information on chemicals reviewed in the CHEMINFO database is drawn from a number of publicly available sources. A list of general references used to compile CHEMINFO records is available in the database Help.

Review/Preparation Date: 1997-02-06

Revision Indicators:
US transport 1998-03-01
Resistance of materials 1998-06-01
TLV-STEL 1998-06-01
TLV comments 1998-06-01
EU Class 2000-04-01
EU Risk 2000-04-01
EU Safety 2000-04-01
EU Comments 2000-04-01
Bibliography 2000-04-01
TDG 2002-05-09
US transport 2002-12-18
Bibliography 2003-04-11
Carcinogenicity 2003-06-16
WHMIS disclosure list 2003-06-16
PEL-TWA final 2003-10-30
PEL-STEL final 2003-10-30
PEL transitional comments 2003-10-30
Resistance of materials for PPE 2004-03-28

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