2,2,4-trimethylpentane

Isooctane
Brief description	Reference fuel (RON = 100 by definition)
properties
Physical state	liquid
calorific value	8.6 kWh / L = 12.5 kWh / kg
Octane number	100 RON (by definition)
Flash point	−9 ° C
Ignition temperature	410 ° C
Explosive limit	0.7-6% by volume
Temperature class	T2
Explosion class	IIA
safety instructions
UN number	1262
Hazard number	33
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Structural formula
General
Surname	2,2,4-trimethylpentane
other names	iso- octane; Isooctane; Isobutyl trimethyl methane;
Molecular formula	C 8 H 18
Brief description	colorless liquid that smells like petrol
External identifiers / databases
EC number	208-759-1
ECHA InfoCard	100.007.964
PubChem	10907
Wikidata	Q209130
properties
Molar mass	114.23 g mol −1
Physical state	liquid
density	0.69 g cm −3
Melting point	−107 ° C
boiling point	99 ° C
Vapor pressure	53 h Pa (20 ° C); 200 hPa (50 ° C); 345 hPa (65 ° C);
solubility	very bad in water (2.1 mg l −1 at 20 ° C)
Refractive index	1.3884 (25 ° C)
safety instructions
H and P phrases	H: 225-304-315-336-410
	P: 210-233-240-273-301 + 310-302 + 352-304 + 340-331-403 + 235
MAK	not specified, as it may be carcinogenic
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

2,2,4-Trimethylpentane (often also called isooctane ) is a colorless liquid substance that chemically belongs to the group of saturated, branched hydrocarbons ( alkanes ). It is an isomer of octane . With the help of 2,2,4-trimethylpentane, the octane number scale was established, a measure of the knock resistance of a petrol . By definition, 2,2,4-trimethylpentane is assigned an octane number of 100.

Extraction and presentation

2,2,4-Trimethylpentane is obtained by dimerization and subsequent hydrogenation of isobutene or from isobutene and isobutane .

properties

Physical Properties

2,2,4-Trimethylpentane is a colorless liquid with a gasoline-like odor. The boiling point is 99 ° C at normal pressure . The heat of vaporization is 30.79 kJ mol ⁻¹ . According to Antoine, the vapor pressure function results from log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 3.93679, B = 1257.840 and C = −52.415 in the temperature range from 297.5 K to 373.3 K. The critical data are the critical temperature with T _c = 270.65 ° C, the critical pressure with p _c = 25.7 bar and an acentric factor with ω _c = 0 , 30346 known. The solubility in water at 25 ° C is extremely low at 2.2 · 10 ⁻⁴ % by mass. Conversely, only 0.011% by mass of water dissolves in 2,2,4-trimethylpentane at 25 ° C. The compound forms azeotropically boiling mixtures with a number of other solvents . The azeotropic compositions and boiling points can be found in the following table. No azeotropes are formed with n- heptane , n- octane , cyclohexane , toluene , ethylbenzene and carbon tetrachloride .

Azeotropes with various solvents
solvent		water	Methanol	Ethanol	n -propanol	2-propanol	Isobutanol	2-butanol	Acetonitrile
Content C ₈ H ₁₈	in%	89	47	58	59	46	73	66	40
boiling point	in ° C	79	59	72	85	77	92	88	69

Safety-related parameters

2,2,4-Trimethylpentane forms highly flammable vapor-air mixtures. The compound has a flash point of −9 ° C. The explosion range is between 0.7% by volume (34 g / m ³ ) as the lower explosion limit (LEL) and 6% by volume (290 g / m ³ ) as the upper explosion limit (UEL). The maximum explosion pressure is 9 bar. The limit gap width was determined to be 0.98 mm. This results in an assignment to explosion group IIA. The ignition temperature is 410 ° C. The substance therefore falls into temperature class T2.

use

Improvement of the knock resistance in petrol
Aviation fuel (calorific value: 44.7 MJ / kg)
Solvent for paints
is for the production of paraffin (eg. for candles) or certain types of polyethylene used
Carrier / matrix for chemical analyzes, especially in petroleum chemistry

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y Entry on 2,2,4-trimethylpentane in the GESTIS substance database of the IFA , accessed on June 26, 2017(JavaScript required) .
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-508.
↑ Entry on 2,2,4-trimethylpentane in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
^ V. Majer, V. Svoboda: Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation. Blackwell Scientific Publications, Oxford 1985, p. 300.
↑ CB Willingham, WJ Taylor, JM Pignocco, FD Rossini: Vapor Pressures and Boiling Points of Some Paraffin, Alkylcyclopentane, Alkylcyclohexane, and Alkylbenzene Hydrocarbons. In: J. Res. Natl. Bur. Stand. (US). 35, 1945, pp. 219-244.
↑ J. Schmidt: Design of safety valves for multi-purpose systems according to ISO 4126-10. In: Chem. Ing. Techn. 83, 2011, pp. 796-812, doi: 10.1002 / cite.201000202 .
^ ^A ^b ^c ^d I. M. Smallwood: Handbook of organic solvent properties. Arnold, London 1996, ISBN 0-340-64578-4 , pp. 27-29.
↑ ^a ^b ^c ^d ^e ^f E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y Entry on 2,2,4-trimethylpentane in the GESTIS substance database of the IFA , accessed on June 26, 2017(JavaScript required) .

[CRC90_3_508-2] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-508.

[CLP_100.007.964-3] Entry on 2,2,4-trimethylpentane in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[Majer-4] V. Majer, V. Svoboda: Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation. Blackwell Scientific Publications, Oxford 1985, p. 300.

[5] CB Willingham, WJ Taylor, JM Pignocco, FD Rossini: Vapor Pressures and Boiling Points of Some Paraffin, Alkylcyclopentane, Alkylcyclohexane, and Alkylbenzene Hydrocarbons. In: J. Res. Natl. Bur. Stand. (US). 35, 1945, pp. 219-244.

[6] J. Schmidt: Design of safety valves for multi-purpose systems according to ISO 4126-10. In: Chem. Ing. Techn. 83, 2011, pp. 796-812, doi: 10.1002 / cite.201000202 .

[Smallwood-7] A ^b ^c ^d I. M. Smallwood: Handbook of organic solvent properties. Arnold, London 1996, ISBN 0-340-64578-4 , pp. 27-29.

[Brandes-8] ↑ ^a ^b ^c ^d ^e ^f E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.