Cyclohexa-1,4-diene

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1,4-Cyclohexadiene is an organic compound with the formula C6H8. It is a colourless, flammable liquid that is of academic interest as a prototype of a large class of related compounds called terpenoids, an example being γ-terpinene. An isomer of this compound is 1,3-cyclohexadiene.

Cyclohexa-1,4-diene
Skeletal formula with all implicit hydrogen shown, skeletal formula; stereo, skeletal formula with all explicit hydrogens added, all of 1,4-cyclohexadiene
1,4-Cyclohexadiene molecule
1,4-Cyclohexadiene molecule
Names
Preferred IUPAC name
Cyclohexa-1,4-diene[1]
Other names
1,4-Cyclohexadiene[citation needed]
1,4-Dihydrobenzene[citation needed]
Identifiers
3D model (JSmol)
Abbreviations 1,4-CHDN
1900733
ChEBI
ChemSpider
ECHA InfoCard 100.010.040 Edit this at Wikidata
EC Number
  • 211-043-1
1656
MeSH 1,4-cyclohexadiene
UNII
UN number 3295
  • InChI=1S/C6H8/c1-2-4-6-5-3-1/h1-2,5-6H,3-4H2 checkY
    Key: UVJHQYIOXKWHFD-UHFFFAOYSA-N checkY
  • C1C=CCC=C1
Properties
C6H8
Molar mass 80.130 g·mol−1
Appearance Colorless liquid
Density 0.847 g cm−3
Melting point −50 °C; −58 °F; 223 K
Boiling point 82 °C; 179 °F; 355 K
-48.7·10−6 cm3/mol
1.472
Thermochemistry
142.2 J K−1 mol−1
189.37 J K−1 mol−1
63.0-69.2 kJ mol−1
-3573.5--3567.5 kJ mol−1
Hazards
GHS labelling:
GHS02: Flammable GHS08: Health hazard
Danger
H225, H340, H350, H373
P201, P210, P308+P313
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
3
0
Flash point −7 °C (19 °F; 266 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis and reactions

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In the laboratory, substituted 1,4-cyclohexadienes are synthesized by Birch reduction of related aromatic compounds using an alkali metal dissolved in liquid ammonia and a proton donor such as an alcohol. In this way, over reduction to the fully saturated ring is avoided.

1,4-Cyclohexadiene and its derivatives are easily aromatized, the driving force being the formation of an aromatic ring. The conversion to an aromatic system may be used to trigger other reactions, such as the Bergman cyclization.[2]

References

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  1. ^ "1,4-cyclohexadiene - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 27 March 2005. Identification and Related Records. Retrieved 12 October 2011.
  2. ^ John C. Walton, Fernando Portela-Cubillo "1,4-Cyclohexadiene" Encyclopedia of Reagents for Organic Synthesis 2007 John Wiley & Sons. doi:10.1002/047084289X.rn00806
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