OCTANE

Octane
Octane Octane Octane
General
Molecular formula	C8H18
SMILES	CCCCCCCC
Molar mass	114.2285 g/mol
Appearance	colorless liquid
CAS number	[111-65-9]
Properties
Density and phase	0.703 g/ml, liquid
Solubility in water	Immiscible
Melting point	−57 °C (216 K)
Boiling point	125.52 °C (398.7 K)
Viscosity	0.542 cP at 20 °C
Thermodynamic data
Std enthalpy change of formation, Δf''H''oliquid	−250 kJ/mol
Std enthalpy change of combustion, Δc''H''oliquid	−5430 kJ/mol
Standard molar entropy, ''S''oliquid	360 J·K−1·mol−1
Hazards
MSDS	External MSDS
EU classification	Flammable ('F') Harmful ('Xn') Dangerous for the environment ('N')
NFPA 704
R-phrases	, , , ,
S-phrases	, , , , , , ,
Flash point	13 °C
Autoignition temperature	220 °C
Explosive limits	1.0–6.5%
RTECS number	RG8400000
Supplementary data page
Structure and properties	''n'', εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related alkanes	Heptane 2,2,4-Trimethylpentane
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

'Octane' is an alkane with the chemical formula CH₃(CH₂)₆CH₃. It has 18 isomers.
One of the isomers, 2,2,4-trimethylpentane or isooctane, is of major importance, as it has been selected as the 100 point on the octane rating scale, with ''n''-heptane as the zero point. Octane ratings are ratings used to represent the anti-knock performance of petroleum-based fuels (octane is less likely to prematurely combust under pressure than heptane), given as the percentage of 2,2,4-trimethylpentane in an 2,2,4-trimethylpentane / ''n''-heptane mixture that would have the same performance. It is an important constituent of gasoline.
Octane has 18 isomers :

★ Octane (''n''-octane)

★ 2-Methylheptane

★ 3-Methylheptane

★ 4-Methylheptane

★ 3-Ethylhexane

★ 2,2-Dimethylhexane

★ 2,3-Dimethylhexane

★ 2,4-Dimethylhexane

★ 2,5-Dimethylhexane

★ 3,3-Dimethylhexane

★ 3,4-Dimethylhexane

★ 2-Methyl-3-ethylpentane

★ 3-Methyl-3-ethylpentane

★ 2,2,3-Trimethylpentane

★ 2,2,4-Trimethylpentane (isooctane)

★ 2,3,3-Trimethylpentane

★ 2,3,4-Trimethylpentane

★ 2,2,3,3-Tetramethylbutane

Contents

External links

External links

★ (''n''-octane)

★

★ Material Safety Data Sheet for Octane

★ Phytochemical database entry

★ Chemical and physical properties table