Octane

{{Short description|Hydrocarbon compound with the formula C8H18}}

{{Distinguish|octene|octyne}}

{{for-multi|the gasoline rating system|Octane rating|other uses}} {{Chembox

| ImageFile = Octane-2D-Skeletal.svg

| ImageClass = skin-invert-image

| ImageFile1 = OctaneFull.png

| ImageClass1 = skin-invert-image

| ImageFile2 = Octane 3D ball.png

| ImageClass2 = bg-transparent

| ImageFile3 = N-octane-spaceFilling.png

| ImageClass3 = bg-transparent

| ImageAlt = Skeletal formula of octane

| ImageFile_Ref = {{chemboximage|correct|??}}

| ImageAlt1 = Skeletal formula of octane with all implicit carbons shown, and all explicit hydrogens added

| ImageFile1_Ref = {{chemboximage|correct|??}}

| ImageAlt2 = Ball-and-stick model of octane

| ImageFile2_Ref = {{chemboximage|correct|??}}

| ImageSize3 = 160

| ImageAlt3 = Space-filling model of octane

| ImageFile3_Ref = {{chemboximage|correct|??}}

| OtherNames = n-Octane

| SystematicName = Octane{{Cite web|title=octane - Compound Summary|url=https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=356&loc=ec_rcs|work=PubChem Compound|publisher=National Center for Biotechnology Information|access-date=6 January 2012|location=USA|date=16 September 2004|at=Identification and Related Records}}

| Section1 = {{Chembox Identifiers

| CASNo = 111-65-9

| CASNo_Ref = {{cascite|correct|CAS}}

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = X1RV0B2FJV

| PubChem = 356

| ChemSpiderID = 349

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| EINECS = 203-892-1

| UNNumber = 1262

| DrugBank = DB02440

| DrugBank_Ref = {{drugbankcite|changed|drugbank}}

| KEGG = C01387

| KEGG_Ref = {{keggcite|correct|kegg}}

| MeSHName = octane

| ChEBI = 17590

| ChEBI_Ref = {{ebicite|changed|EBI}}

| ChEMBL = 134886

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| RTECS = RG8400000

| Beilstein = 1696875

| Gmelin = 82412

| 3DMet = B00281

| SMILES = CCCCCCCC

| StdInChI = 1S/C8H18/c1-3-5-7-8-6-4-2/h3-8H2,1-2H3

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = TVMXDCGIABBOFY-UHFFFAOYSA-N

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

}}

| Section2 = {{Chembox Properties

| Formula = {{chem2|CH3(CH2)6CH3}}

| C=8|H=18

| Appearance = Colourless liquid

| Odor = Gasoline-like

| Density = 0.703 g/cm³

| MeltingPtK = 216.0 to 216.6

| BoilingPtK = 398.2 to 399.2

| Solubility = 0.007 mg/dm³ (at 20 °C)

| LogP = 4.783

| VaporPressure = 1.47 kPa (at 20.0 °C)

| HenryConstant = 29 nmol/(Pa·kg)

| RefractIndex = 1.398

| Viscosity = {{plainlist|

• 0.509 mPa·s (25 °C){{cite journal|last1=Dymond|first1=J. H.|last2=Oye|first2=H. A.|title=Viscosity of Selected Liquid n-Alkanes|journal=Journal of Physical and Chemical Reference Data|volume=23|issue=1|year=1994|pages=41–53|issn=0047-2689|doi=10.1063/1.555943|bibcode=1994JPCRD..23...41D}}
• 0.542 mPa·s (20 °C)}}

| MagSus = −96.63·10⁻⁶ cm³/mol

| ConjugateAcid = Octonium

}}

| Section3 = {{Chembox Thermochemistry

| DeltaHf = −252.1 to −248.5 kJ/mol

| DeltaHc = −5.53 to −5.33 MJ/mol

| Entropy = 361.20 J/(K·mol)

| HeatCapacity = 255.68 J/(K·mol)

}}

| Section4 = {{Chembox Hazards

| GHSPictograms = {{GHS flame}} {{GHS exclamation mark}} {{GHS health hazard}} {{GHS environment}}

| GHSSignalWord = DANGER

| NFPA-H = 1

| NFPA-F = 3

| NFPA-R = 0

| HPhrases = {{H-phrases|225|304|315|336|410}}

| PPhrases = {{P-phrases|210|261|273|301+310|331}}

| FlashPtC = 13.0

| AutoignitionPtC = 220.0

| ExploLimits = 0.96 – 6.5%

| IDLH = 1000 ppm{{PGCH|0470}}

| REL = TWA 75 ppm (350 mg/m³) C 385 ppm (1800 mg/m³) [15-minute]

| PEL = TWA 500 ppm (2350 mg/m³)

| LDLo = 428 mg/kg (mouse, intravenous){{IDLH|111659|Octane}}

}}

| Section5 = {{Chembox Related

| OtherFunction_label = alkanes

| OtherFunction = {{Unbulleted list|Methane|Ethane|Propane|Butane|Pentane|Hexane|Heptane|}}

}}

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 411133144

}}

Octane is a hydrocarbon and also an alkane with the chemical formula C₈H₁₈, and the condensed structural formula CH₃(CH₂)₆CH₃. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (commonly called iso-octane), is used as one of the standard values in the octane rating scale.

Octane is a component of gasoline and petroleum. Under standard temperature and pressure, octane is an odorless, colorless liquid. Like other short-chained alkanes with a low molecular weight, it is volatile, flammable, and toxic. Octane is 1.2 to 2 times more toxic than heptane.{{Cite web |date=2020-02-27 |title=1988 OSHA PEL Project - Octane {{!}} NIOSH {{!}} CDC |url=https://www.cdc.gov/niosh/pel88/111-65.html |access-date=2024-04-19 |website=www.cdc.gov }}