Cyclohexa-1,3-diene

Cyclohexa-1,3-diene
Names
	Preferred IUPAC name Cyclohexa-1,3-diene
	Other names 1,3-Cyclohexadiene, 1,2-Dihydrobenzene, 1,3-CHD
Identifiers
CAS Number	592-57-4 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	506024
ChEBI	CHEBI:37610 ;
ChemSpider	11117 ;
ECHA InfoCard	100.008.878
EC Number	209-764-1;
Gmelin Reference	1657
PubChem CID	11605;
RTECS number	GU4702350;
UNII	JV5W0EG5BP ;
UN number	1993
CompTox Dashboard (EPA)	DTXSID30862259 ;
	InChI InChI=1S/C6H8/c1-2-4-6-5-3-1/h1-4H,5-6H2 Key: MGNZXYYWBUKAII-UHFFFAOYSA-N ; InChI=1/C6H8/c1-2-4-6-5-3-1/h1-4H,5-6H2 Key: MGNZXYYWBUKAII-UHFFFAOYAH;
	SMILES C\1=C\C=C/CC/1;
Properties
Chemical formula	C6H8
Molar mass	80.13 g/mol
Appearance	Colorless liquid
Density	0.841 g/cm3
Melting point	−98 °C (−144 °F; 175 K)
Boiling point	80 °C (176 °F; 353 K)
Magnetic susceptibility (χ)	-48.6·10−6 cm3/mol
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H335
Precautionary statements	P210, P233, P240, P241, P242, P243, P261, P271, P280, P303 P361 P353, P304 P340, P312, P370 P378, P403 P233, P403 P235, P405, P501
Flash point	26 °C (79 °F; 299 K) c.c.
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Cyclohexa-1,3-diene is an organic compound with the formula (C₂H₄)(CH)₄. It is a colorless, flammable liquid. Its refractive index is 1.475 (20 °C, D). It is one of two isomers of cyclohexadiene, the other being 1,4-cyclohexadiene.

Synthesis

Cyclohexadiene is prepared by the double dehydrobromination of 1,2-dibromocyclohexane:^[1]

(CH₂)₄(CHBr)₂ 2 NaH → (CH₂)₂(CH)₄ 2 NaBr 2 H₂

Reactions

Useful reactions of this diene are cycloadditions, such as the Diels-Alder reaction.^[2]

Conversion of cyclohexa-1,3-diene to benzene hydrogen is exothermic by about 25 kJ/mol in the gas phase.^[3]^[4]

cyclohexane → cyclohexa-1,3-diene 2 H₂ (ΔH = 231.5 kJ/mol; endothermic)

cyclohexane → benzene 3 H₂ (ΔH = 205 kJ/mol; endothermic)

cyclohexa-1,3-diene → benzene H₂ (ΔH = -26.5 kJ/mol; exothermic)

Compared with its isomer cyclohexa-1,4-diene, cyclohexa-1,3-diene is about 1.6 kJ/mol more stable.^[5]

Cyclohexadiene and its derivatives form (diene)iron tricarbonyl complexes. Illustrative is [(C₆H₈)Fe(CO)₃], an orange liquid. This complex reacts with hydride-abstracting reagents to give the cyclohexadienyl derivative [(C₆H₇)Fe(CO)₃].^[6] Cyclohexadienes react with ruthenium trichloride to give (Benzene)ruthenium dichloride dimer.^[7]

Occurrence

Cyclohexa-1,3-diene itself is rare in nature, but the cyclohexa-1,3-diene motif is fairly common.^[8] One example is chorismic acid, an intermediate in the shikimic acid pathway. Of the several examples of the terpenoids and terpenes, a prominent example is phellandrene. An unusual derivative is cis-1,2-dihydrocatechol.

Coenzyme A-conjugated to the 2-position of cyclohexadiene-2-carboxylic acid is an intermediate in the biodegradation of aromatic carboxylic acids.^[9]

References

^ Schaefer, John P.; Endres, Leland (1967). "1,3-Cyclohexadiene". Organic Syntheses. 47: 31. doi:10.15227/orgsyn.047.0031.
^ Sanjeeva Rao Guppi, George A. O'Doherty, "1,3-Cyclohexadiene" Encyclopedia of Reagents for Organic Synthesis, 2008 John Wiley & Sons. doi:10.1002/047084289X.rn00921
^ US National Institute of Standards and Technology, NIST Chemistry WebBook 1,3-Cyclohexadiene Benzene
^ J. Sherman The heats of hydrogenation of unsaturated hydrocarbons Archived 2011-07-14 at the Wayback Machine Journal of the American Oil Chemists' Society; Volume 16, Number 2 / February, 1939
^ NIST Chemistry WebBook 1,4-Cyclohexadiene
^ Pearson, Anthony J.; Sun, Huikai (2008). "Cyclohexadieneiron Tricarbonyl". E-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00791. ISBN 978-0471936237.
^ Bennett, M. A.; Huang, T. N.; Matheson, T. W.; Smith, A. K. (1982). "16. (η6 -Hexamethylbenzene)Ruthenium Complexes". (η⁶-Hexamethylbenzene)ruthenium Complexes. Inorganic Syntheses. Vol. 21. pp. 74–78. doi:10.1002/9780470132524.ch16. ISBN 9780470132524.74-78&rft.date=1982&rft_id=info:doi/10.1002/9780470132524.ch16&rft.isbn=9780470132524&rft.aulast=Bennett&rft.aufirst=M. A.&rft.au=Huang, T. N.&rft.au=Matheson, T. W.&rft.au=Smith, A. K.&rfr_id=info:sid/en.wikipedia.org:Cyclohexa-1,3-diene" class="Z3988">
^ Gribble, G.W. (1991). "Natural Products Containing a Cyclohexane, Cyclohexene, or Cyclohexadiene Subunit". Second Supplements to the 2nd Edition of Rodd's Chemistry of Carbon Compounds. pp. 375–445. doi:10.1016/B978-044453347-0.50066-5. ISBN 978-0-444-53347-0.375-445&rft.date=1991&rft_id=info:doi/10.1016/B978-044453347-0.50066-5&rft.isbn=978-0-444-53347-0&rft.aulast=Gribble&rft.aufirst=G.W.&rfr_id=info:sid/en.wikipedia.org:Cyclohexa-1,3-diene" class="Z3988">
^ Porter, A. W.; Young, L. Y. (2014). "Benzoyl-CoA, a Universal Biomarker for Anaerobic Degradation of Aromatic Compounds". Advances in Applied Microbiology. 88: 167–203. doi:10.1016/B978-0-12-800260-5.00005-X. ISBN 978-0-12-800260-5. PMID 24767428.167-203&rft.date=2014&rft_id=info:pmid/24767428&rft_id=info:doi/10.1016/B978-0-12-800260-5.00005-X&rft.isbn=978-0-12-800260-5&rft.aulast=Porter&rft.aufirst=A. W.&rft.au=Young, L. Y.&rfr_id=info:sid/en.wikipedia.org:Cyclohexa-1,3-diene" class="Z3988">

[1] Schaefer, John P.; Endres, Leland (1967). "1,3-Cyclohexadiene". Organic Syntheses. 47: 31. doi:10.15227/orgsyn.047.0031.

[2] Sanjeeva Rao Guppi, George A. O'Doherty, "1,3-Cyclohexadiene" Encyclopedia of Reagents for Organic Synthesis, 2008 John Wiley & Sons. doi:10.1002/047084289X.rn00921

[3] US National Institute of Standards and Technology, NIST Chemistry WebBook 1,3-Cyclohexadiene Benzene

[4] J. Sherman The heats of hydrogenation of unsaturated hydrocarbons Archived 2011-07-14 at the Wayback Machine Journal of the American Oil Chemists' Society; Volume 16, Number 2 / February, 1939

[5] NIST Chemistry WebBook 1,4-Cyclohexadiene

[6] Pearson, Anthony J.; Sun, Huikai (2008). "Cyclohexadieneiron Tricarbonyl". E-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00791. ISBN 978-0471936237.

[7] Bennett, M. A.; Huang, T. N.; Matheson, T. W.; Smith, A. K. (1982). "16. (η6 -Hexamethylbenzene)Ruthenium Complexes". (η⁶-Hexamethylbenzene)ruthenium Complexes. Inorganic Syntheses. Vol. 21. pp. 74–78. doi:10.1002/9780470132524.ch16. ISBN 9780470132524.74-78&rft.date=1982&rft_id=info:doi/10.1002/9780470132524.ch16&rft.isbn=9780470132524&rft.aulast=Bennett&rft.aufirst=M. A.&rft.au=Huang, T. N.&rft.au=Matheson, T. W.&rft.au=Smith, A. K.&rfr_id=info:sid/en.wikipedia.org:Cyclohexa-1,3-diene" class="Z3988">

[8] Gribble, G.W. (1991). "Natural Products Containing a Cyclohexane, Cyclohexene, or Cyclohexadiene Subunit". Second Supplements to the 2nd Edition of Rodd's Chemistry of Carbon Compounds. pp. 375–445. doi:10.1016/B978-044453347-0.50066-5. ISBN 978-0-444-53347-0.375-445&rft.date=1991&rft_id=info:doi/10.1016/B978-044453347-0.50066-5&rft.isbn=978-0-444-53347-0&rft.aulast=Gribble&rft.aufirst=G.W.&rfr_id=info:sid/en.wikipedia.org:Cyclohexa-1,3-diene" class="Z3988">

[Porter-9] Porter, A. W.; Young, L. Y. (2014). "Benzoyl-CoA, a Universal Biomarker for Anaerobic Degradation of Aromatic Compounds". Advances in Applied Microbiology. 88: 167–203. doi:10.1016/B978-0-12-800260-5.00005-X. ISBN 978-0-12-800260-5. PMID 24767428.167-203&rft.date=2014&rft_id=info:pmid/24767428&rft_id=info:doi/10.1016/B978-0-12-800260-5.00005-X&rft.isbn=978-0-12-800260-5&rft.aulast=Porter&rft.aufirst=A. W.&rft.au=Young, L. Y.&rfr_id=info:sid/en.wikipedia.org:Cyclohexa-1,3-diene" class="Z3988">

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Cyclohexa-1,3-diene

Contents

Synthesis

Reactions

Occurrence

See also

References