Chemistry:P-Cymene

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p-Cymene
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
1-Methyl-4-(propan-2-yl)benzene[1]
Other names
para-Cymene
4-Isopropyltoluene
4-Methylcumene
Paracymene
Identifiers
3D model (JSmol)
3DMet
1903377
ChEBI
ChEMBL
ChemSpider
EC Number
  • 202-796-7
305912
KEGG
RTECS number
  • GZ5950000
UNII
UN number 2046
Properties
C10H14
Molar mass 134.222 g·mol−1
Appearance Colourless liquid
Density 0.857 g/cm3
Melting point −68 °C (−90 °F; 205 K)
Boiling point 177 °C (351 °F; 450 K)
23.4 mg/L
−1.028×10−4 cm3/mol
1.4908 (at 20 °C) [2]
Hazards
GHS pictograms GHS02: FlammableGHS08: Health hazardGHS09: Environmental hazard
GHS Signal word Danger
H226, H304, H411
P210, P233, P240, P241, P242, P243, P273, P280, P301+310, P303+361+353, P331, P370+378, P391, P403+235, P405, P501
Flash point 47 °C (117 °F; 320 K)
435 °C (815 °F; 708 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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Infobox references

p-Cymene is a naturally occurring aromatic organic compound. It is classified as an alkylbenzene related to monocyclic monoterpenes.[3] Its structure consists of a benzene ring para-substituted with a methyl group and an isopropyl group. p-Cymene is insoluble in water, but miscible with organic solvents.

Isomers and production

In addition to p-cymene, two less common geometric isomers are o-cymene, in which the alkyl groups are ortho-substituted, and m-cymene, in which they are meta-substituted. p-Cymene is the only natural isomer, as expected from the terpene rule. All three isomers form the group of cymenes.

Cymene is also produced by alkylation of toluene with propene.[4]

Related compounds

It is a constituent of a number of essential oils, most commonly the oil of cumin and thyme. Significant amounts are formed in sulfite pulping process from the wood terpenes.

p-Cymene is a common ligand for ruthenium. The parent compound is [(η6-cymene)RuCl2]2. This half-sandwich compound is prepared by the reaction of ruthenium trichloride with the terpene α-phellandrene. The osmium complex is also known.[5]

Hydrogenation gives the saturated derivative p-menthane.

References

  1. Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 139, 597. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4. 
  2. Pabst, Florian; Blochowicz, Thomas (December 2022). "On the intensity of light scattered by molecular liquids - Comparison of experiment and quantum chemical calculations" (in en). The Journal of Chemical Physics 157 (24): 244501. doi:10.1063/5.0133511. PMID 36586992. Bibcode2022JChPh.157x4501P. 
  3. Balahbib, Abdelaali; El Omari, Nasreddine; Hachlafi, Naoufal EL.; Lakhdar, Fatima; El Menyiy, Naoual; Salhi, Najoua; Mrabti, Hanae Naceiri; Bakrim, Saad et al. (2021-07-01). "Health beneficial and pharmacological properties of p-cymene". Food and Chemical Toxicology 153: 112259. doi:10.1016/j.fct.2021.112259. ISSN 0278-6915. https://www.sciencedirect.com/science/article/abs/pii/S0278691521002921#:~:text=p%2Dcymene%20also%20known%20as,of%20terpenes%2C%20especially%20monocyclic%20monoterpenes.. 
  4. Vora, Bipin V.; Kocal, Joseph A.; Barger, Paul T.; Schmidt, Robert J.; Johnson, James A. (2003). "Alkylation". Kirk‐Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.0112112508011313.a01.pub2. ISBN 0471238961. 
  5. Bennett, M. A.; Huang, T.-N.; Matheson, T. W.; Smith, A. K. (1982). "(η6-Hexamethylbenzene)Ruthenium Complexes". Inorganic Syntheses 21: 74–78. doi:10.1002/9780470132524.ch16. ISBN 9780470132524.