Cyclopentene

Structural formula
General
Surname	Cyclopentene
Molecular formula	C 5 H 8
Brief description	colorless liquid with a slightly sweet odor
External identifiers / databases
EC number	205-532-9
ECHA InfoCard	100.005.030
PubChem	8882
Wikidata	Q415233
properties
Molar mass	68.12 g mol −1
Physical state	liquid
density	0.77 g cm −3 (20 ° C)
Melting point	−135 ° C
boiling point	46 ° C
Vapor pressure	416 h Pa (20 ° C)
solubility	practically insoluble in water (535 mg l −1 at 25 ° C)
Dipole moment	0.93 D (in carbon tetrachloride )
Refractive index	1.4194
safety instructions
H and P phrases	H: 225-302-312-304-315
	P: 280-302 + 352-210-301 + 310-331-362-302 + 352-331
Toxicological data	1656 mg kg −1 ( LD 50 , rat , oral )
	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

Cyclopentene is an organic compound with the empirical formula C ₅ H ₈ . It consists of a five-membered, unsaturated ring which has a double bond . In the homologous series of cycloalkenes , cyclopentene stands between cyclobutene and cyclohexene . Formally, it is a singly hydrogenated cyclopentadiene or a singly dehydrogenated cyclopentane . Cyclopentene has only a few uses.

presentation

Cyclopentene is by steam cracking of naphtha available, with about 2.2 kg per metric ton of naphtha cyclopentene incurred. On the other hand, it is produced more efficiently by the catalytic hydrogenation of cyclopentadiene.

properties

Cyclopentene enters into the usual reactions for cyclic alkenes, such as additions to the double bond and cycloadditions . Substitution reactions usually take place in the allylic position. By the catalytic oxidation of cyclopentene with oxygen can be cyclopentanone synthesize. The stereoselective formation of trans -Tricyclo [5.3.0.0 ^2,6 ] decane by photochemical dimerization of cyclopentene is a simple example of a photodimerization by [2 + 2] cycloaddition:

The reaction proceeds with a 55% yield.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on cyclopentene in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
↑ ^a ^b ^c ^d D. Hönicke, R. Födisch, P. Claus, M. Olson: Cyclopentadiene and Cyclopentene , in: Ullmanns Enzyklopädie der Technischen Chemie 2002 , Wiley-VCH, Weinheim.
↑ Data sheet Cyclopenten at AlfaAesar, accessed on March 2, 2010 ( PDF )(JavaScript required) .
↑ J. Smidt, W. Hafner, R. Jira, J. Sedlmeier, R. Sieber, R. Rüttinger, H. Kojer: Catalytic reactions of olefins on platinum metal compounds The Consortium process for the production of acetaldehyde , in: Angew. Chem. 1959 , 71 , 176-182; doi : 10.1002 / anie.19590710503 .
^ ^A ^b Albert Gossauer: Structure and Reactivity of Biomolecules , Verlag Helvetica Chimica Acta, Zurich, 2006, p. 143, ISBN 978-3-906390-29-1 .

[gestis-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on cyclopentene in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

[ul-2] D. Hönicke, R. Födisch, P. Claus, M. Olson: Cyclopentadiene and Cyclopentene , in: Ullmanns Enzyklopädie der Technischen Chemie 2002 , Wiley-VCH, Weinheim.

[3] Data sheet Cyclopenten at AlfaAesar, accessed on March 2, 2010 ( PDF )(JavaScript required) .

[4] J. Smidt, W. Hafner, R. Jira, J. Sedlmeier, R. Sieber, R. Rüttinger, H. Kojer: Catalytic reactions of olefins on platinum metal compounds The Consortium process for the production of acetaldehyde , in: Angew. Chem. 1959 , 71 , 176-182; doi : 10.1002 / anie.19590710503 .

[Gossauer-5] A ^b Albert Gossauer: Structure and Reactivity of Biomolecules , Verlag Helvetica Chimica Acta, Zurich, 2006, p. 143, ISBN 978-3-906390-29-1 .