1-Methylcyclohexene an organic compound consisting of cyclohexene with a methyl group substituent attached to the alkene group. Two other structural isomers are known: 3-methylcyclohexene and 4-methylcyclohexene. All are colorless volatile liquids. They are specialized reagents. Methylcyclohexenes are a cyclic olefins.
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| Names | |
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| IUPAC name
1-Methylcyclohexene
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| Systematic IUPAC name
1-Methylcyclohexene | |
Other names
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| Identifiers | |
3D model (JSmol)
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| 1304483 | |
| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.008.836 |
| EC Number |
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PubChem CID
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| UNII | |
| UN number | 3295 |
CompTox Dashboard (EPA)
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| Properties | |
| C7H12 | |
| Molar mass | 96.173 g·mol−1 |
| Appearance | colorless liquid |
| Density | 0.811 g/mL at 20 °C |
| Melting point | −120.4 °C (−184.7 °F; 152.8 K) |
| Boiling point | 110 °C (230 °F; 383 K) |
| 0.052 g/kg for 1-methylcyclohexene | |
Refractive index (nD)
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1.44 |
| Hazards | |
| GHS labelling: | |
  
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| Warning | |
| H225, H304, H315, H319, H335 | |
| P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P301+P310, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P312, P321, P331, P332+P313, P337+P313, P362, P370+P378, P403+P233, P403+P235, P405, P501 | |
| Flash point | −3 °C (27 °F; 270 K) |
| Safety data sheet (SDS) | MSDS (1-methylcyclohexene) |
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
editMethylcyclohexenes are formed by the partial hydrogenation of toluene to methylcyclohexane over ruthenium catalyst.[1]
Ozonolysis of 1-methylcyclohexene results in ring-opening.[2]
Stereochemical probe
edit1-Methylcyclohexene is used as a probe of the stereochemistry of reactions involving alkenes because it is prochiral and the two sp2-carbon atoms differ.
The regioselectivity and stereoselectivity of hydrosilylation of 1-methylcyclohexene with chloro(methyl)silanes depends on the number of chlorine atoms in the hydrosilylating agent.[3] Using chlorodimethylsilane produces a mixture of seven different products including cis- and trans-isomers of 2-, 3-, 4-chlorodimethyl(methylcyclohexyl)silanes and chlorodimethyl(cyclohexylmethyl)silane. The poor selectivity is due to the migration of the double bond in the cyclohexene ring. Reaction with dichloromethylsilane is more regioselective and stereoselective, only giving three of the seven products obtained from monochlorodimethylsilane. With trichloromethylsilane, trichlorocyclohexylmethylsilane is the only possible product and is obtained at 60 percent yield. All these products can be further reacted with Grignard reagents such as ethynylmagnesium bromide to synthesize ethynyl derivatives.
Oxidation of 1-methylcyclohexene catalyzed by cytochrome P450 yields a 2:1 mixture of hydroxylation to epoxidation products.[4]
The stereochemistry of hydroformylation has been examined using 1-methylcyclohexene. The main product has the formyl group on the less substituted alkene-carbon, trans with respect to the methyl substituent.[5]
References
edit- ^ Belohlav, H.; Kluson, P.; Cerveny, L. (1997). "Partial Hydrogenation of Toluene Over A Ruthenium Catalyst, A Model Treatment of A Deactivation Process". Res. Chem. Intermed. 32 (2): 161–168. doi:10.1163/156856797X00312. S2CID 95532469.
- ^ Atkinson, Roger; Tuazon, Ernesto C.; Aschmann, Sara M. (1995). "Products". Environ. Sci. Technol. (29). doi:10.1029/98JD00524.
- ^ Voronkov, M.; et al. (December 2004). "Hydrosilylation of Cyclohexene, 1-Methylcyclohexene, and Isopropylidenecyclohexane". Russian Journal of General Chemistry. 74 (12): 1895–1899. doi:10.1007/s11176-005-0114-4. S2CID 98097289.
- ^ Khan, M. M. T.; Rao, A. P.; Bhatt, S. D.; Merchant, R. R. (1990). "Epoxidation of cyclohexene, methylcyclohexene and cis-cyclooctene by molecular oxygen using ruthenium(III) aquo ion as catalyst: A kinetic study". Journal of Molecular Catalysis. 62 (3): 265–276. doi:10.1016/0304-5102(90)85222-4.
- ^ Molnár, Árpád; Olah, George A.; Surya Prakash, G. K. (2017). "Carbonylation and Carboxylation". Hydrocarbon Chemistry. Wiley. pp. 509–568. doi:10.1002/9781119390541.ch7. ISBN 978-1-119-39051-0.