Octane (C8H18): structure, properties and hazards

Names and identifiers

IUPAC name: octane
Synonyms: n-octane, Oktan, Oktanen
+ 34 more
Ottani, DTXSID0026882, X1RV0B2FJV, NSC-9822, DTXCID406882, CHEBI:17590, normal-Octane, RefChem:6664, 203-892-1, 608-610-4, Oktanen [Dutch], Oktan [Polish], Ottani [Italian], n-Oktan, MFCD00009556, CH3-[CH2]6-CH3, Heptane, methyl-, Normal octane, Octane, all isomers, Octane; NSC 9822; n-Octane, octano, HSDB 108, NSC 9822, EINECS 203-892-1, UNII-X1RV0B2FJV, Octil, AI3-28789, MG8, n-OCTANE, REAG, N-OCTANE [HSDB], OCTANE [MI], bmse000480, EC 203-892-1, n-Octane; >98.5%
Molecular formula: C₈H₁₈
Empirical formula: C₄H₉
Molecular weight: 114.23 g/mol
Exact mass: 114.14085
CAS number: 111-65-9
PubChem CID: 356
Canonical SMILES: CCCCCCCC
Isomeric SMILES: CCCCCCCC
InChI: InChI=1S/C8H18/c1-3-5-7-8-6-4-2/h3-8H2,1-2H3
InChIKey: TVMXDCGIABBOFY-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity

Appearance: Clear liquid[6]
7 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– N-octane is a colorless liquid with an odor of gasoline. Less dense than water and insoluble in water. Hence floats on water. Produces irritating vapor. [1] CAMEO Chemicals
– Liquid [2] EPA Chemical Data Reporting (CDR)
– COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– Colorless liquid with a gasoline-like odor. [4] Occupational Safety and Health Administration (OSHA)
– Colorless liquid with a gasoline-like odor. [5] The National Institute for Occupational Safety and Health (NIOSH)
– Colorless liquid [6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 918
–shown Clear liquid [6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. V3: 2762
Odor: Gasoline-like[6]
Melting point: -56.8 °C[3]
4 values
4 of 4 sources agree on it (most common value).
Value As written Source
−56.8 °C -70.2 °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.
−56.8 °Cshown -56.8 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−57 °C -70 °F [4] Occupational Safety and Health Administration (OSHA)
−57 °C -70 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Boiling point: 125.8 °C @760 [mmHg][7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
125.6 °C 258.1 °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.
126 °C 126 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
126 °C 258 °F [4] Occupational Safety and Health Administration (OSHA)
125.8 °Cshown 125.8 °C @760 [mm Hg] [7] PAC Chemical Database, U.S. Department of Energy
126 °C 258 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Density: 0.7036 @25 °C[7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
– 0.703 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.
– Relative density (water = 1): 0.70 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 0.7 [4] Occupational Safety and Health Administration (OSHA)
–shown 0.7036 @25 °C [7] PAC Chemical Database, U.S. Department of Energy
– 0.70 [5] The National Institute for Occupational Safety and Health (NIOSH)
Solubility in water: Solubility in water: none[3]
4 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– 7e-05 % at 77 °F (NIOSH, 2024) [1] CAMEO Chemicals
– In water, 0.66 mg/L at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan., Handbook of Aqueous Solubility Data: An Extensive Compilation of Aqueous Solubility Data for Organic Compounds Extracted from the AQUASOL dATAbASE. CRC Press LLC, Boca Raton, FL. 2003., p. 536
–shown Solubility in water: none [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– (77 °F): 0.00007% [5] The National Institute for Occupational Safety and Health (NIOSH)
log P: 4.00/5.18[3]
2 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
– log Kow = 5.18 [6] Hazardous Substances Data Bank (HSDB)cites Miller MM et al; Environ Sci Technol 19: 522-9 (1985)
–shown 4.00/5.18 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Vapor pressure: Vapor pressure, kPa at 20 °C: 1.33[3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
10 mmHgshown Vapor pressure, kPa at 20 °C: 1.33 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
10 mmHg 10 [mm Hg] @19.2 °C [7] PAC Chemical Database, U.S. Department of Energy
3 more values were reported but failed the checks (unreadable or out of range), so they are not shown.
Flash point: 13 °C c.c.[3]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
13 °C 56 °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.
13 °C 56 °F (13 °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. 325-93
13 °Cshown 13 °C c.c. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
13 °C 56 °F [4] Occupational Safety and Health Administration (OSHA)
13 °C 56 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Autoignition temperature: 220 °C[3]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source
220 °C 428 °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.
206 °C 403 °F (206 °C) [6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-93
220 °Cshown 220 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Viscosity: 0.5151 cP at 25 °C[6]
Refractive index: Index of refraction: 1.3974 at 20 °C[6]

Value	As written	Source
–	N-octane is a colorless liquid with an odor of gasoline. Less dense than water and insoluble in water. Hence floats on water. Produces irritating vapor.	[1] CAMEO Chemicals
–	Liquid	[2] EPA Chemical Data Reporting (CDR)
–	COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	Colorless liquid with a gasoline-like odor.	[4] Occupational Safety and Health Administration (OSHA)
–	Colorless liquid with a gasoline-like odor.	[5] The National Institute for Occupational Safety and Health (NIOSH)
–	Colorless liquid	[6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 918
–shown	Clear liquid	[6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. V3: 2762

Value	As written	Source
−56.8 °C	-70.2 °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.
−56.8 °Cshown	-56.8 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−57 °C	-70 °F	[4] Occupational Safety and Health Administration (OSHA)
−57 °C	-70 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
125.6 °C	258.1 °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.
126 °C	126 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
126 °C	258 °F	[4] Occupational Safety and Health Administration (OSHA)
125.8 °Cshown	125.8 °C @760 [mm Hg]	[7] PAC Chemical Database, U.S. Department of Energy
126 °C	258 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	0.703 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.
–	Relative density (water = 1): 0.70	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	0.7	[4] Occupational Safety and Health Administration (OSHA)
–shown	0.7036 @25 °C	[7] PAC Chemical Database, U.S. Department of Energy
–	0.70	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	7e-05 % at 77 °F (NIOSH, 2024)	[1] CAMEO Chemicals
–	In water, 0.66 mg/L at 25 °C	[6] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan., Handbook of Aqueous Solubility Data: An Extensive Compilation of Aqueous Solubility Data for Organic Compounds Extracted from the AQUASOL dATAbASE. CRC Press LLC, Boca Raton, FL. 2003., p. 536
–shown	Solubility in water: none	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	(77 °F): 0.00007%	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	log Kow = 5.18	[6] Hazardous Substances Data Bank (HSDB)cites Miller MM et al; Environ Sci Technol 19: 522-9 (1985)
–shown	4.00/5.18	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
10 mmHgshown	Vapor pressure, kPa at 20 °C: 1.33	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
10 mmHg	10 [mm Hg] @19.2 °C	[7] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
13 °C	56 °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.
13 °C	56 °F (13 °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. 325-93
13 °Cshown	13 °C c.c.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
13 °C	56 °F	[4] Occupational Safety and Health Administration (OSHA)
13 °C	56 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
220 °C	428 °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.
206 °C	403 °F (206 °C)	[6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-93
220 °Cshown	220 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

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: 8
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 1
H-bond donors: 0
H-bond acceptors: 0
Rotatable bonds: 5
TPSA (Å²): 0
Formal charge: 0
XLogP3: 3.9 PubChem
Complexity: 25 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: C2 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C84.12%
H15.88%

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: 3.37 Crippen (Wildman and Crippen 1999)
log S (water solubility): -2.34 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 1.3 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 114.23
log P ≤ 5 (Crippen): 3.37
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
Harmful or irritant
Health hazard
Environmental hazard

NFPA 704[6]

H225Highly Flammable liquid and vapor
H304May be fatal if swallowed and enters airways
H315Causes skin irritation
H336May cause drowsiness or dizziness
H400Very toxic to aquatic life
H410Very toxic to aquatic life with long lasting effects

Precautionary statements: P210, P233, P240, P241, P242, P243, P261, P264, P271, P273, P280, P301+P316, P302+P352, P303+P361+P353, P304+P340, P319, P321, P331, P332+P317, P362+P364, P370+P378, P391, P403+P233, P403+P235, P405, P501

View all classifications (2)

[8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH225, H304, H315, H336, H400, H410
[9] European Chemicals Agency (ECHA) · 1,560 reports · DangerH225, H302, H304, H312, H315, H319, H336, H400, H410

Exposure limits

PEL-TWA (8-Hour Time Weighted Average): 500 ppm (2350 mg/m³)[4]
PEL: TWA 500 ppm (2350 mg/m3) See Appendix G[5]
REL-TWA (Time Weighted Average): 75 ppm (350 mg/m³)[4]
REL-C (Ceiling): 385 ppm (1800 mg/m³) [15 minutes][4]
REL: TWA 75 ppm (350 mg/m3) C 385 ppm (1800 mg/m3) [15-minute][5]
TLV: 300 ppm as TWA.[3]

First aid

Excerpt from NIOSH Pocket Guide for Octane: Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: SOAP WASH promptly - If this chemical contacts the skin, promptly wash the contaminated skin with soap and water. If this chemical penetrates the clothing, promptly remove the clothing and wash the skin with soap and water.[1]
(General first aid procedures) Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: Soap wash promptly - If this chemical contacts the skin, promptly wash the contaminated skin with soap and water. If this chemical penetrates the clothing, promptly remove the clothing and wash the skin with soap and water.[5]
Fresh air, rest. Refer for medical attention.[3]
Remove contaminated clothes. Rinse skin with plenty of water or shower.[3]

Storage

Fireproof. Separated from strong oxidants. Cool. Ventilation along the floor.[3]
Store in cool place. Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage.[6]

Incompatibilities

Strong oxidizers.[6]
Strong oxidizers[5]

Safety data sheets on the supplier’s page: VladaChem, Thermo Fisher Scientific, Sigma-Aldrich.

Always read the supplier’s safety data sheet before working with it.

Spectra

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]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[11]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[12]SpectraBase · 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.

Similar structures

Tanimoto similarity on Morgan fingerprints (radius 2) with RDKit 2026.09, at least 45%.