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p-Cymene
Skeletal formula	Ball-and-stick model
Names
	Preferred IUPAC name 1-Methyl-4-(propan-2-yl)benzene
	Other names para-Cymene; 4-Isopropyltoluene; 4-Methylcumene; Paracymene
Identifiers
CAS Number	99-87-6 ;
3D model (JSmol)	Interactive image;
3DMet	B00975;
Beilstein Reference	1903377
ChEBI	CHEBI:28768;
ChEMBL	ChEMBL442915 ;
ChemSpider	7183 ;
ECHA InfoCard	100.002.542
EC Number	202-796-7;
Gmelin Reference	305912
KEGG	C06575 ;
PubChem CID	7463;
RTECS number	GZ5950000;
UNII	1G1C8T1N7Q ;
UN number	2046
CompTox Dashboard (EPA)	DTXSID3026645 ;
	InChI InChI=1S/C10H14/c1-8(2)10-6-4-9(3)5-7-10/h4-8H,1-3H3 Key: HFPZCAJZSCWRBC-UHFFFAOYSA-N ; InChI=1/C10H14/c1-8(2)10-6-4-9(3)5-7-10/h4-8H,1-3H3 Key: HFPZCAJZSCWRBC-UHFFFAOYAD;
	SMILES c1cc(ccc1C(C)C)C;
Properties
Chemical formula	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)
Solubility in water	23.4 mg/L
Magnetic susceptibility (χ)	−1.028×10−4 cm3/mol
Refractive index (nD)	1.4908 (at 20 °C)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H226, H304, H411
Precautionary statements	P210, P233, P240, P241, P242, P243, P273, P280, P301+P310, P303+P361+P353, P331, P370+P378, P391, P403+P235, P405, P501
Flash point	47 °C (117 °F; 320 K)
Autoignition; temperature	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). verify (what is ?) 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

^ 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.
^ Pabst, Florian; Blochowicz, Thomas (December 2022). "On the intensity of light scattered by molecular liquids - Comparison of experiment and quantum chemical calculations". The Journal of Chemical Physics. 157 (24): 244501. Bibcode:2022JChPh.157x4501P. doi:10.1063/5.0133511. PMID 36586992.
^ Balahbib, Abdelaali; El Omari, Nasreddine; Hachlafi, Naoufal EL.; Lakhdar, Fatima; El Menyiy, Naoual; Salhi, Najoua; Mrabti, Hanae Naceiri; Bakrim, Saad; Zengin, Gokhan; Bouyahya, Abdelhakim (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.
^ 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.
^ 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.