2,2,4-trimethylpentane
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | 2,2,4-trimethylpentane | |||||||||||||||
other names |
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Molecular formula | C 8 H 18 | |||||||||||||||
Brief description |
colorless liquid that smells like petrol |
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External identifiers / databases | ||||||||||||||||
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properties | ||||||||||||||||
Molar mass | 114.23 g mol −1 | |||||||||||||||
Physical state |
liquid |
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density |
0.69 g cm −3 |
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Melting point |
−107 ° C |
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boiling point |
99 ° C |
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Vapor pressure |
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solubility |
very bad in water (2.1 mg l −1 at 20 ° C) |
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Refractive index |
1.3884 (25 ° C) |
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safety instructions | ||||||||||||||||
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MAK |
not specified, as it may be carcinogenic |
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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 |
Isooctane | |
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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 . |
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.