Cyclohexa-1,3-diene
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| Names | |||
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| IUPAC name
Cyclohexa-1,3-diene
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| Other names
1,3-Cyclohexadiene, 1,2-Dihydrobenzene, 1,3-CHD
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| Identifiers | |||
3D model (JSmol)
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| ChemSpider | |||
| ECHA InfoCard | 100.008.878 | ||
PubChem CID
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| RTECS number |
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CompTox Dashboard (EPA)
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| Properties | |||
| C6H8 | |||
| Molar mass | 80.13 g/mol | ||
| Appearance | Colourless liquid | ||
| Density | 0.841 g/cm³ | ||
| Melting point | −98 °C (−144 °F; 175 K) | ||
| Boiling point | 80 °C (176 °F; 353 K) | ||
| Hazards | |||
| Flash point | 26 °C c.c. | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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1,3-Cyclohexadiene is a highly flammable cycloalkene that occurs as a colorless clear liquid. Its refractive index is 1.475 (20 °C, D).
It can be used as a hydrogen donor in transfer hydrogenation, since its conversion to benzene + hydrogen is in fact exothermic (about 20 kJ/mol in the gas phase, as indicated by heats of hydrogenation). [1] [2] Despite this apparent instability with respect to benzene, the 1,3-cyclohexadiene structure is found in several natural products such as α-terpinene.
Compared with 1,4-cyclohexadiene, 1,3-cyclohexadiene is about 1.6 kJ/mol less stable, due to the less favourable electronic distribution. [3]
See also
References
- ^ US National Institute of Standards and Technology, NIST Chemistry WebBook 1,3-Cyclohexadiene Benzene
cyclohexane → 1,3-cyclohexadiene: ΔH +224 kJ/mol; cyclohexane → benzene: ΔH +205 kJ; 1,3-cyclohexadiene → benzene: ΔH -19 kJ - ^ J. Sherman The heats of hydrogenation of unsaturated hydrocarbons Journal of the American Oil Chemists' Society; Volume 16, Number 2 / February, 1939
- ^ NIST Chemistry WebBook 1,4-Cyclohexadiene