Methylcyclohexene

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Methylcyclohexene
Names
IUPAC name
1-Methylcyclohexene,3-Methylcyclohexene, 4-Methylcyclohexene
Systematic IUPAC name
1-Methylcyclohexene,3-Methylcyclohexene, 4-Methylcyclohexene
Other names
2,3,4,5-Tetrahydrotoluene or 1-Methyl-1-Cyclohexene (1-Methylcyclohexene), 1,2,3,6-Tetrahydrotoluene (4-Methylcyclohexene)
Identifiers
3D model (
JSmol
)
1304483 (1-methylcyclohexene), 1848550 (3-methylcyclohexene), 1901299 (4-methylcyclohexene)
ChemSpider
EC Number
  • 1-: 209-718-0
  • 3-: 209-717-5
  • 4-: 209-715-4
UNII
UN number 3295
  • 1-: InChI=1S/C7H12/c1-7-5-3-2-4-6-7/h5H,2-4,6H2,1H3
    Key: CTMHWPIWNRWQEG-UHFFFAOYSA-N
  • 3-: InChI=1S/C7H12/c1-7-5-3-2-4-6-7/h3,5,7H,2,4,6H2,1H3
    Key: UZPWKTCMUADILM-UHFFFAOYSA-N
  • 4-: InChI=1S/C7H12/c1-7-5-3-2-4-6-7/h2-3,7H,4-6H2,1H3
    Key: FSWCCQWDVGZMRD-UHFFFAOYSA-N
  • 1-: CC1=CCCCC1
  • 3-: CC1CCCC=C1
  • 4-: CC1CCC=CC1
Properties
C7H12
Molar mass 96.170 g/mol for 1-methylcyclohexene
Appearance clear, liquid, colorless for 1-methylcyclohexene
Density 0.811 g/mL at 20 °C for 1-methylcyclohexene, 0.805 g/mL for 3-methylcyclohexene, 0.799 g/mL for 4-methylcyclohexene
Melting point -120.4°C for 1-methylcyclohexene at 1 atm, -124 °C for 3-methylcyclohexene, -115.5 °C 4-methylcyclohexene
Boiling point 110 °C for 1-methylcyclohexene at 1 atm, 104 °C for 3-methylcyclohexene, 103 °C 4-methylcyclohexene
0.052 g/kg for 1-methylcyclohexene
1.44 for 1-methylcyclohexene
Hazards
GHS labelling:
GHS02: FlammableGHS07: Exclamation markGHS08: Health hazard
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
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).

Methylcyclohexene refers to any one of three organic compounds consisting of cyclohexene with a methyl group substituent. The location of the methyl group relative to the cyclohexene double bond creates the three different structural isomers. These compounds are generally used as a reagent or intermediate to derive other organic compounds.[1]

Methylcyclohexenes are a cyclic olefins. Cyclic olefins can come together to form

polymers
. These polymers are thermoplastics that are advantageous due to their low moisture intake, their ability to resist high temperatures, have low bireinfringence, and excellent transparency. This type of polymer material is very useful in medical instruments, packaging, fibers, and optics.

As simple molecules, methylcyclohexenes are generally available from different biochemical manufacturers.[citation needed]

Synthesis

Synthesis of methylcyclohexene

There are different ways to produce methylcyclohexenes. A mixture of 1- and 2-methylcyclohexene can be produced by first reacting

Diels–Alder reaction.[citation needed
]

Methylcyclohexene is also formed as a by-product in the hydrogenation of toluene to methylcyclohexane over ruthenium catalyst, which can lead to catalyst poisoning if the catalyst is insufficiently activated. Catalysts that have not been sufficiently hydrogenated prior to introduction of toluene will experience poisoning of active sites by methylcyclohexene, as the double bond adsorbs strongly to the catalyst surface.[2]

Structure and bonding

bond lengths

The isomers of methylcyclohexene each contain a six carbon ring structure, with one carbon-carbon double bond within the ring and one methyl substituent on the ring.[3] The bond lengths in 1-methylcyclohexene are approximately 1.33 Å between C1 (the carbon in the ring with the methyl substituent) and C2 (the second carbon of the double bond), 1.51 Å between C2 and C3 (the next carbon around the ring) and between C6 and C1, 1.54 Å between C3 and C4, between C4 and C5, and between C5 and C6, and 1.50 Å between C1 and the carbon of the methyl substituent. The bond lengths of the other isomers of methylcyclohexene vary slightly from 1-methylcyclohexene, due to the different position of the double bond with respect to the methyl substituent.

Reactions

Ozonolysis

As an unsaturated molecule, methylcyclohexene can undergo oxidation with several oxidizing agents, including the strong oxidizing agent

carbonyl compounds.[4]

Hydrosilyation

"Hydrosilylation of Cyclohexene"

The

ethynyl derivatives
.

Oxidation with Cytochrome P450

1-methylcyclohexene can be oxidized with a Cytochrome P450 catalyst. The ratio of hydroxylation products to epoxidation products was shown to be 2:1.[6]

Bromination

Bromination of methylcyclohexene
Bromination of methylcyclohexene

In the presence of a

Cinchona alkaloid, bromination of an alkene leads to optically active dibromides.[7]
For 4-methylcyclohexene, the (S)-configuration leads to two different products: the bromines can add at the axial positions, giving the orientation (1S:3R:4R), or at the equatorial positions, giving the orientation (1S:3S:4S). Similarly, the (R)-configuration produces two different products: axial addition yields the configuration (1R:3S:4S) and equatorial addition yields (1R:3R:4R).

References

  1. doi:10.1117/1.1369411
    .
  2. S2CID 95532469
    .
  3. ^ Handbook of Chemistry & Physics Online Section 4.
  4. doi:10.1029/98JD00524
    .
  5. S2CID 98097289
    .
  6. doi:10.1016/0304-5102(90)85222-4
    .
  7. doi:10.1016/S0040-4020(01)82993-8
    .
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