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Cymene describes organic compounds with the formula CH₃C₆H₄CH(CH₃)₂. Three isomers exist: 1,2- 1,3-, and 1,4-. All are colorless liquids, immiscible in water, with similar boiling points. They are classified are aromatic hydrocarbons. The bearing two substituents: an isopropyl (CH(CH₃)₂) group and a methyl group.^[1]

Cymenes
Name	o-Cymene	m-Cymene	p-Cymene
Structural formula
CAS number	527-84-4	535-77-3	99-87-6
melting point (°C)	−71.54	−63.75	−67.94
boiling point (°C)	178.15	175.05	177.10

Production and reactions

m- and p-Cymene are prepared by alkylation of toluene with propylene:

CH₃C₆H₅ + 2 CH₃CH=CH₂ → CH₃C₆H₄CH(CH₃)₂

These alkylations are catalyzed by various Lewis acids, such as aluminium trichloride.

m- and p-Cymene are mainly of interest as precursors to the respective cresols, which exploits the Hock rearrangements.^[1]

References

^ ^a ^b Schmidt, Roland; Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter; Höke, Hartmut (2014). "Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–74. doi:10.1002/14356007.a13_227.pub3. ISBN 9783527306732.

Hydrocarbons

Saturated
aliphatic
hydrocarbons

Alkanes
C_nH_{2n + 2}

Linear alkanes	Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane
Branched alkanes	Isobutane Isopentane 3-Methylpentane Neopentane Isohexane Isoheptane Isooctane Isononane Isodecane

Cycloalkanes

Alkylcycloalkanes

Bicycloalkanes

Housane (bicyclo[2.1.0]pentane)
Norbornane (bicyclo[2.2.1]heptane)
Decalin (bicyclo[4.4.0]decane)

Polycycloalkanes

Other

Spiroalkanes

Unsaturated
aliphatic
hydrocarbons

Alkenes
C_nH_2n

Linear alkenes	Ethene Propene Butene Pentene Hexene Heptene Octene Nonene Decene
Branched alkenes	Isobutene Isopentene Isohexene Isoheptene Isooctene Isononene Isodecene

Alkynes
C_nH_{2n − 2}

Linear alkynes	Ethyne Propyne Butyne Pentyne Hexyne Heptyne Octyne Nonyne Decyne
Branched alkynes	Isopentyne Isohexyne Isoheptyne Isooctyne Isononyne Isodecyne

Cycloalkenes

Alkylcycloalkenes

Bicycloalkenes

Norbornene

Cycloalkynes

Dienes

Other

Aromatic
hydrocarbons

PAHs

Acenes	Naphthalene Anthracene Tetracene Pentacene Hexacene Heptacene
Other	Azulene Fluorene Helicenes Circulenes Butalene Phenanthrene Chrysene Pyrene Corannulene Kekulene

Alkylbenzenes

Toluene

C2-Benzenes

Xylenes	o-Xylene m-Xylene p-Xylene
Other	Ethylbenzene

C3-Benzenes

Trimethylbenzenes	Mesitylene Pseudocumene Hemellitene
Other	Cumene n-Propylbenzene 4-Ethyltoluene

C4-Benzenes

Cymenes	o-Cymene m-Cymene p-Cymene
Tetramethylbenzenes	Durene Prehnitene Isodurene
Other	n-Butylbenzene sec-Butylbenzene tert-Butylbenzene Isobutylbenzene

Other

Vinylbenzenes

Other

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