Isobutane
Athanor · official
C4H10 · 58.12 g/mol
IUPAC name: 2-methylpropane
Also called 2-methylpropane, i-butane
DangerExtremely flammable gasNames and identifiers
- IUPAC name
- 2-methylpropane
- Synonyms
- 2-methylpropane, i-butane, 2-Methylpropane
+ 37 more
Trimethylmethane, 1,1-Dimethylethane, iso-butane, R 600a, Caswell No. 503A, R-600a, HSDB 608, EINECS 200-857-2, UNII-BXR49TP611, EPA Pesticide Chemical Code 097101, BXR49TP611, E943b, (CH3)2CH-CH3, DTXSID1026401, CHEBI:30363, EC 200-857-2, ISOBUTANE (II), ISOBUTANE [II], ISOBUTANE (MART.), ISOBUTANE [MART.], RefChem:5911, PROPANE, 2-METHYL, DTXCID806401, 200-857-2, Propane, 2-methyl-, Isobutane [NF], Isobutane (NF), MFCD00008926, 2-METHYL-D3-PROPANE-1,1,1,3,3,3-D6, dimethylethane, Methylpropane, iso butane, tert-Butane, i-Butane, MEB, H-tBu, ISOBUTANE [FCC]
- Molecular formula
- C4H10
- Empirical formula
- C2H5
- Molecular weight
- 58.12 g/mol
- Exact mass
- 58.07825
- CAS number
- 75-28-5
- PubChem CID
- 6360
- Canonical SMILES
- CC(C)C
- Isomeric SMILES
- CC(C)C
- InChI
- InChI=1S/C4H10/c1-4(2)3/h4H,1-3H3
- InChIKey
- NNPPMTNAJDCUHE-UHFFFAOYSA-N
- Molfile
Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.
Physical properties
TemperaturePressureDensity
- Appearance
- Colorless gas [Note: Shipped as a liquified compressed gas. A liquid below -12 °C (11 °F)][6]
6 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source – Isobutane is a colorless gas with a faint petroleum-like odor. It is shipped as a liquefied gas under its vapor pressure. Contact with the liquid can cause frostbite. It is easily ignited. The vapors are heavier than air. Any leak can either be liquid or vapor. It can asphyxiate by the displacement of air. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. [1] CAMEO Chemicals – CBI; Gas Vapor; Liquid; Gas Vapor; Liquid [2] EPA Chemical Data Reporting (CDR) – COLOURLESS COMPRESSED LIQUEFIED GAS WITH CHARACTERISTIC ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs) – Colorless gas with a gasoline-like or natural gas odor. [4] Occupational Safety and Health Administration (OSHA) – Colorless gas with a gasoline-like or natural gas odor. [Note: Shipped as a liquefied compressed gas. A liquid below 11 °F.] [5] The National Institute for Occupational Safety and Health (NIOSH) –shown Colorless gas [Note: Shipped as a liquified compressed gas. A liquid below 11 °F] [6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg - Odor
- Slight odor[6]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source – Gasoline-like or natural gas odor. [6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg –shown Slight odor [6] Hazardous Substances Data Bank (HSDB)cites Larranaga, M.D., Lewis, R.J. Sr., Lewis, R.A.; Hawley's Condensed Chemical Dictionary 16th Edition. John Wiley & Sons, Inc. Hoboken, NJ 2016., p. 776 - Melting point
- -159.4 °C[7]
5 values
4 of 5 sources agree on it (most common value).
Value As written Source −159 °C -255 °F (NIOSH, 2024) [1] CAMEO Chemicals −160 °C -160 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs) −138.3 °C -216.9 °F [4] Occupational Safety and Health Administration (OSHA) −159.4 °Cshown -159.4 °C [7] PAC Chemical Database, U.S. Department of Energy −159 °C -255 °F [5] The National Institute for Occupational Safety and Health (NIOSH) - Boiling point
- -11.73 °C @760 [mmHg][7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source −11.8 °C 10.8 °F at 760 mmHg (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office. −12 °C -12 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs) −11.8 °C 10.8 °F [4] Occupational Safety and Health Administration (OSHA) −11.7 °Cshown -11.73 °C @760 [mm Hg] [7] PAC Chemical Database, U.S. Department of Energy −12 °C 11 °F [5] The National Institute for Occupational Safety and Health (NIOSH) - Density
- 0.55092 g/cu cm at 25 °C[6]
8 values
Only one source reports it.
Value As written Source – 0.557 at 68 °F (USCG, 1999) - Less dense than water [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office. 0.55092 g/mLshown 0.55092 g/cu cm at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 80 0.55711 g/mL 0.55711 g/cu cm at 20 °C [6] Hazardous Substances Data Bank (HSDB)cites Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 80 – 0.61415 at -29.5 °C [6] Hazardous Substances Data Bank (HSDB)cites Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 80 – Relative density (water = 1): 0.6 (liquid) [3] ILO-WHO International Chemical Safety Cards (ICSCs) – 0.557 [4] Occupational Safety and Health Administration (OSHA) – 0.551 @25 °C [7] PAC Chemical Database, U.S. Department of Energy – 2.06(relative gas density) [5] The National Institute for Occupational Safety and Health (NIOSH) - Solubility in water
- Solubility in water at 20 °C: none[3]
4 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source – Slight (NIOSH, 2024) [1] CAMEO Chemicals – In water, 48.9 mg/L at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites McAuliffe C; J Phys Chem 70: 1267-75 (1966) –shown Solubility in water at 20 °C: none [3] ILO-WHO International Chemical Safety Cards (ICSCs) – Slight [5] The National Institute for Occupational Safety and Health (NIOSH) - log P
- log Kow = 2.76[6]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source –shown log Kow = 2.76 [6] Hazardous Substances Data Bank (HSDB)cites Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 10 – 2.8 [3] ILO-WHO International Chemical Safety Cards (ICSCs) - Vapor pressure
- 3.1 atm at 21 °C (70 °F, NIOSH 2024)[1]
6 values
2 of 5 sources agree on it (most common value).
Value As written Source 2400 mmHgshown 3.1 atm at 70 °F (NIOSH, 2024) [1] CAMEO Chemicals 2610 mmHg 2610 mm Hg (348.1 kPa) at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 80 391.02 mmHg 391.02 mm Hg (52.132 kPa) at -27.57 °C [6] Hazardous Substances Data Bank (HSDB)cites Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 80 2300 mmHg Vapor pressure, kPa at 20 °C: 304 [3] ILO-WHO International Chemical Safety Cards (ICSCs) 2400 mmHg 3.1 atm at 70 °F [4] Occupational Safety and Health Administration (OSHA) 750 mmHg 750 [mm Hg] @-12 °C [7] PAC Chemical Database, U.S. Department of Energy 1 more value was reported but failed the checks (unreadable or out of range), so it is not shown.
- Flash point
- -82.99 °C (-117.38 °F) - closed cup[6]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source −83 °C -117 °F (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office. −83.0 °Cshown -82.99 °C (-117.38 °F) - closed cup [6] Hazardous Substances Data Bank (HSDB)cites Sigma-Aldrich; Safety Data Sheet for 2-Methylpropane. Product Number: 295450, Version 4.5 (Revision Date 06/07/2015). Available from, as of December 20, 2017: https://www.sigmaaldrich.com/safety-center.html −83 °C -117 °F [4] Occupational Safety and Health Administration (OSHA) - Autoignition temperature
- 460 °C[3]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source 477 °C 890 °F (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office. 460 °C 860 °F (460 °C) (Closed cup) [6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-74 460 °Cshown 460 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs) - Viscosity
- 0.238 cP at -10 °C[6]
Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.
Calculated
- Heavy atoms
- 4
- Rings
- 0
- Aromatic rings
- 0
- Fraction sp³ carbons (Fsp3)
- 1
- H-bond donors
- 0
- H-bond acceptors
- 0
- Rotatable bonds
- 0
- TPSA (Ų)
- 0
- Formal charge
- 0
- XLogP3
- 2.1 PubChem
- Complexity
- 4 PubChem
- Stereocenters
- None
- Double-bond geometry
- None specified
- Point group
- C3v of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)
Elemental analysis
- C82.66%
- H17.34%
Isotope pattern
Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.
Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.
Predicted
- log P
- 1.66 Crippen (Wildman and Crippen 1999)
- log S (water solubility)
- -1.25 ESOL (Delaney 2004), log mol/L
- Synthetic accessibility
- 1.84 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)
Drug-likeness: Lipinski’s rule of five
- Molecular weight ≤ 500: 58.12
- log P ≤ 5 (Crippen): 1.66
- H-bond donors ≤ 5: 0
- H-bond acceptors ≤ 10: 0
Passes all four rules.
¹³C NMR shifts, predicted
Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.
Safety
Danger
Harmonized EU classification (CLP Annex VI). Source [8].
- Flammable
- Compressed gas
- H220Extremely flammable gas
Precautionary statements: P203, P210, P222, P280, P377, P381, P403
View all classifications (4)
- [8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH220
- [8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH220, H340, H350
- [9] European Chemicals Agency (ECHA) · 2,477 reports · DangerH220, H280
- [6] Hazardous Substances Data Bank (HSDB) · DangerH220, H280
Exposure limits
First aid
- Excerpt from NIOSH Pocket Guide for Isobutane: Eye: Frostbite - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible. Skin: Frostbite - If frostbite has occurred, seek medical attention immediately; do NOT rub the affected areas or flush them with water.[1]
- General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[10]
- General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[10]
- (General first aid procedures) Eye: Frostbite - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible. Skin: Frostbite - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard.[5]
Storage
- Fireproof. Cool.[3]
- Keep container tightly closed in a dry and well-ventilated place. Contents under pressure. Storage class (TRGS 510): Gases.[6]
- Store separately from all other flammable materials. Prior to working with this chemical, you should be trained on its proper handling and storage. Before entering confined space where isobutane may be present, check to make sure that an explosive concentration odes not exist. Isobutane cylinders should be stored in a cool, well-ventilated dry area of noncombustible construction. Protect containers against physical damage. Store away from sources of heat or ignition and from oxygen, chlorine, and other oxidizers.[6]
Incompatibilities
- Incompatible materials: Strong oxidizing agents.[6]
- Forms explosive gas mixture with air. Strong oxidizers (e.g., nitrates, perchlorates, chlorine, fluorine) and nickel carbonyl + oxygen may cause fire and explosions. Reacts with acetylene, halogens, and nitrous oxides.[6]
- Reacts with strong oxidants, acetylene, halogens and nitrogen oxides. This generates fire and explosion hazard.[6]
- Strong oxidizers (eg, nitrates & perchlorates), chlorine, fluorine, (nickel carbonyl + oxygen).[6]
Safety data sheets on the supplier’s page: MuseChem, Sigma-Aldrich, ChemoSapiens.
Always read the supplier’s safety data sheet before working with it.
Spectra
- NMRHazardous Substances Data Bank (HSDB)
- 13C NMRSpectraBase
- GC-MSHuman Metabolome Database (HMDB) (EI-B · positive) · MassBank of North America (MoNA) (HITACHI RMU-5B · EI-B · positive) · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center
- Other MSHazardous Substances Data Bank (HSDB) · MassBank Europe (HITACHI RMU-5B · EI-B · POSITIVE)
- IRHazardous Substances Data Bank (HSDB)
- Vapor Phase IRSpectraBase (Gas cell)
- RamanHazardous Substances Data Bank (HSDB) · SpectraBase
Experimental spectra held by these sources; each link opens the source's own record.
Literature
Reading PubChem, OpenAlex and GSRS…
Bioactivity
Reading ChEMBL…
References
- [1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
- [2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
- [3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [4]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
- [5]The National Institute for Occupational Safety and Health (NIOSH) · Public domain (US CDC) · via PubChem · retrieved 2026-10-14
- [6]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
- [7]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
- [8]Regulation (EC) No 1272/2008 of the European Parliament and of the Council · EU reuse policy, CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [9]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
- [10]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
- [11]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
- [12]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
- [13]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [14]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
- [15]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
- ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
- ·Literature on PubChem
Data last updated 2026-10-14.