Pentenes
Pentenes (also called amylenes ) are hydrocarbons with the empirical formula C 5 H 10 that have a carbon-carbon double bond ( C = C double bond for short ). They therefore belong to the group of alkenes . There are five constitutional isomeric pentenes, of which 2- pentene can exist as a cis or trans isomer . Pentenes occur as a mixture of isomers in cracked gases and in natural gas . Another constitutional isomer is cyclopentane , which, however, is not pentene.
Structure and properties
Pentenes | ||||||||||
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Surname | Pent-1-en | cis -pent-2-ene | trans -pent-2-ene | |||||||
other names | 1-pentene, amylene |
( Z ) -Pent-2-ene β-amylene |
( E ) -pent-2-ene β-amylene |
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Structural formula | ||||||||||
CAS number | 109-67-1 | 627-20-3 | 646-04-8 | |||||||
109-68-2 (mixture of isomers) | ||||||||||
Molecular formula | C 5 H 10 | |||||||||
Molar mass | 70.13 g mol −1 | |||||||||
Brief description | colorless, low-boiling, extremely flammable liquids | |||||||||
Melting point | −138 ° C | −151.4 ° C | −136 ° C | |||||||
boiling point | 30 ° C | 36.9 ° C | 36.3 ° C | |||||||
solubility | insoluble in water, easily soluble in ethanol and ether | |||||||||
GHS labeling |
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H and P phrases | 224-304-315-319 | 225-304-315-319-335 | 224-304-315-319-335 | |||||||
no EUH phrases | no EUH phrases | no EUH phrases | ||||||||
210-301 + 310 305 + 351 + 338-331 |
210-261-301 + 310 305 + 351 + 338-331 |
210-261-301 + 310 305 + 351 + 338-331 |
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Pentenes (continued) | ||||||||||
Surname | 2-methyl-1-butene | 2-methyl-but-2-ene | 3-methyl-1-butene | |||||||
other names | Isopentes | 2-methyl-but-3-ene | ||||||||
Structural formula | ||||||||||
CAS number | 563-46-2 | 513-35-9 | 563-45-1 | |||||||
Molecular formula | C 5 H 10 | |||||||||
Molar mass | 70.13 g mol −1 | |||||||||
Brief description | colorless, low-boiling, extremely flammable liquids | |||||||||
Melting point | −137.5 ° C | −133.8 ° C | −169.5 ° C | |||||||
boiling point | 31.2 ° C | 38.6 ° C | 20.1 ° C | |||||||
solubility | insoluble in water, easily soluble in ethanol and ether | |||||||||
GHS labeling |
|
|
|
|||||||
H and P phrases | 224-304 | 225-302 | 224-304-315-319-335 | |||||||
no EUH phrases | no EUH phrases | no EUH phrases | ||||||||
210-301 + 310-331 | 210 | 210-261-301 + 310-305 + 351 + 338-331 |
According to Antoine, the vapor pressure functions result from log 10 (P) = A− (B / (T + C)) (P in bar, T in K) as follows:
Vapor pressure functions of the pentenes T (K) A. B. C. 1-pentene 285.98-303.87 3,91058 1014.294 −43.367 cis -2-pentene 274.74-342.03 3,99984 1069.229 −42.393 trans -2-pentene 274.18-341.36 4.03089 1084.165 −40.158 2-methyl-1-butene 274.30-335.82 3.98652 1047.811 −41.089 2-methyl-2-butene 276.19-343.74 4.04727 1098.619 −39.889 3-methyl-1-butene 273.37-324.29 3.95126 1013,575 −36.32
Extraction
Pentenes are components of coal tar , shale oil , cracked gases and cracked gasoline and can be obtained by fractional distillation . During pyrolysis of rubber , 2-methyl-but-1-ene and 2-methyl-but-2-ene are formed.
Pentenes are formed by dehydration ( elimination of water) from pentanols (so-called amyl alcohols ). In this way, z. B. from fusel oils pentenes (so-called. Fuselölamylen ) win.
use
Pentenes are used for the synthesis of amylphenols , isoprene and pentanols , as well as for polymerization . In addition, amylenes are added as stabilizers, chloroform and dichloromethane , in order to intercept the phosgene formed under the influence of air and light .
Individual evidence
- ↑ Data sheet 1-pentenes from Sigma-Aldrich , accessed on May 6, 2011 ( PDF ).
- ↑ Data sheet cis-2-pentenes from Sigma-Aldrich , accessed on May 6, 2011 ( PDF ).
- ↑ Trans-2-pentenes data sheet from Sigma-Aldrich , accessed on May 6, 2011 ( PDF ).
- ↑ 2-Methyl-1-butene data sheet from Sigma-Aldrich , accessed on May 6, 2011 ( PDF ).
- ↑ 2-Methyl-2-butene data sheet from Sigma-Aldrich , accessed on May 6, 2011 ( PDF ).
- ↑ 3-Methyl-1-butene data sheet from Sigma-Aldrich , accessed on May 6, 2011 ( PDF ).
- ↑ AF Forziati, DL Camin, FD Rossini: density, refractive index, boiling point, and vapor pressure of eight mono-olefin (1-alkenes), six pentadiene, and two cyclomonoolefin hydrocarbons. In: J. Res. NBS. 45, 1950, pp. 406-410.
- ↑ a b c D. W. Scott, G. Waddington: Vapor Pressure of cis-2-pentenes, trans-2-pentenes and 3-methyl-1-butenes. In: J. Am. Chem. Soc. 72, 1950, pp. 4310-4311, ( doi: 10.1021 / ja01165a542 ).
- ^ A b D. W. Scott, G. Waddington, JC Smith, HM Huffman: Thermodynamic properties of three isomeric pentenes. In: J. Am. Chem. Soc. 71, 1949, pp. 2767-2773 ( doi: 10.1021 / ja01176a050 ).
- ↑ Mazin Rida Irani: Stabilized methylene chloride composition and its use for steam degreasing of metals. Patent DE2714836C2 at Patent-de.com, April 2, 1977.