2,2,4-Trimethylpentane

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2,2,4-Trimethylpentane

General
Systematic name	2,2,4-Trimethylpentane
Other names	Isooctane
Molecular formula	(CH₃)₃CCH₂CH(CH₃)₂
SMILES	CC(C)(C)CC(C)C
Molar mass	114.22 g/mol
Appearance	colorless liquid
CAS number	[540-84-1]
Properties
Density and phase	0.688 g/ml, liquid
Solubility in water	Immiscible
Melting point	−107.38 °C (165.77 K)
Boiling point	99.3 °C (372.4 K)
Thermodynamic data
Std enthalpy change of formation, Δ_fH^o_liquid	−259 kJ/mol
Std enthalpy change of combustion, Δ_cH^o_liquid	−5461 kJ/mol
Standard molar entropy, S^o_liquid	328 J·K⁻¹·mol⁻¹
Hazards
MSDS	External MSDS
EU classification	Flammable (F) Harmful (Xn) Dangerous for the environment (N)
NFPA 704	3 0 0
R-phrases	R11, R38, R50/53, R65, R67
S-phrases	S2, S9, S16, S29, S33, S60, S61, S62
Flash point	4.5 °C
Autoignition temperature	417 °C
Explosive limits	1.1–6.0%
RTECS number	SA3320000
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related alkanes	Heptane Octane
Related compounds	Hexadecane
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

2,2,4-Trimethylpentane, also known as isooctane, is an octane isomer which defines the 100 point on the octane rating scale. It is one of the compounds in petrol/gasoline and has an enthalpy of combustion of -48 kJ/g or -33 kJ/cm³.

Iso-octane, usually as a mixture with related hydrocarbons, is produced on a massive scale in the petrol industry. The alkylation process alkylates isobutane with isobutylene using an acid catalyst (sulfuric acid or hydrofluoric acid). In another process, NExOCTANE, isobutylene is dimerized into iso-octene and hydrogenated to iso-octane. ^[1]