Title: Cymene
CAS Registry Number: 25155-15-1
CAS Name: Methyl(1-methylethyl)benzene
Additional Names: isopropyltoluene; methylisopropylbenzene
Molecular Formula: C10H14
Molecular Weight: 134.22
Percent Composition: C 89.49%, H 10.51%
Literature References: Usually prepd by alkylation of toluene; m-, o- and p-isomers obtained: Allen, Yats, J. Am. Chem. Soc. 83, 2799 (1961). Purification and properties of the three isomers: Streiff et al., Anal. Chem. 27, 411 (1955). Separation of the three isomers by gas chromatography: Rihani, Froment, J. Chromatogr. 18, 150 (1965). Toxicity study: P. M. Jenner et al., Food Cosmet. Toxicol. 2, 327 (1964).
Derivative Type: m-Cymene
CAS Registry Number: 535-77-3
Additional Names: 1-Methyl-3-(1-methylethyl)benzene
Properties: Liquid, bp 175.14°. mp -63.75°. d420 0.8610, d425 0.8570. nD20 1.4930, nD25 1.4906. Practically insol in water. Miscible with alcohol, ether.
Melting point: mp -63.75°
Boiling point: bp 175.14°
Index of refraction: nD20 1.4930; nD25 1.4906
Density: d420 0.8610; d425 0.8570
Derivative Type: o-Cymene
CAS Registry Number: 527-84-4
Additional Names: 1-Methyl-2-(1-methylethyl)benzene
Properties: Liquid, bp 178.15°. mp -71.54°; also reported as -75.24° and -81.53° for two unstable solid forms (Streiff). d420 0.8766, d425 0.8726. nD20 1.5006, nD25 1.4982. Practically insol in water. Miscible with organic solvents.
Melting point: mp -71.54°; also reported as -75.24° and -81.53° for two unstable solid forms (Streiff)
Boiling point: bp 178.15°
Index of refraction: nD20 1.5006; nD25 1.4982
Density: d420 0.8766; d425 0.8726
Derivative Type: p-Cymene
CAS Registry Number: 99-87-6
Additional Names: 1-Methyl-4-(1-methylethyl)benzene; Dolcymene
Properties: Occurs in a number of essential oils. Liquid, bp 177.10°. mp -67.94°. d420 0.8573, d425 0.8533. nD20 1.4909, nD25 1.4885. Flash pt, closed cup: 117°F (47°C). Practically insol in water. Misc with alcohol, ether. LD50 orally in rats: 4750 mg/kg (Jenner).
Melting point: mp -67.94°
Boiling point: bp 177.10°
Flash point: Flash pt, closed cup: 117°F (47°C)
Index of refraction: nD20 1.4909; nD25 1.4885
Density: d420 0.8573; d425 0.8533
Toxicity data: LD50 orally in rats: 4750 mg/kg (Jenner)
Cymiazole Cymoxanil Cynanchogenin Cynarin(e) Cypermethrin

Skeletal formula Ball-and-stick model
CAS number 99-87-6 YesY
PubChem 7463
ChemSpider 7183 YesY
EC number 202-796-7
KEGG C06575 YesY
Jmol-3D images Image 1
Molecular formula C10H14
Molar mass 134.21 g/mol
Appearance Colourless liquid
Density 0.857 g/cm3
Melting point -68 °C
Boiling point 177 °C
Solubility in water 23.4 mg/L
R-phrases R10
S-phrases S16
Flash point 47 °C; 117 °F; 320 K
Autoignition temperature 435 °C; 815 °F; 708 K
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

p-Cymene, is a naturally occurring aromatic organic compound. It is classified as an alkylbenzene related to a monoterpene. Its structure consists of a benzene ring para-substituted with a methyl group and an isopropyl group. There are two less common geometric isomers. 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. All three isomers form the group of cymenes.

p-Cymene is insoluble in water, but miscible with ethanol and diethyl ether.

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.[1]