Durene

Durene, or 1,2,4,5-tetramethylbenzene, is an organic compound with the formula C₆H₂(CH₃)₄. It is a colourless solid with a sweet odor. The compound is classified as an alkylbenzene. It is one of three isomers of tetramethylbenzene, the other two being prehnitene (1,2,3,4-tetramethylbenzene) and isodurene (1,2,3,5-tetramethylbenzene). Durene has an unusually high melting point (79.2 °C), reflecting its high molecular symmetry.

Durene

Names
Preferred IUPAC name 1,2,4,5-Tetramethylbenzene
Other names Durol
Identifiers
CAS Number	95-93-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:38978 Y
ChemSpider	6999 Y
ECHA InfoCard	100.002.242
KEGG	C14534 Y
PubChem CID	7269
UNII	181426CFYB Y
CompTox Dashboard (EPA)	DTXSID1029124
InChI InChI=1S/C10H14/c1-7-5-9(3)10(4)6-8(7)2/h5-6H,1-4H3 Y Key: SQNZJJAZBFDUTD-UHFFFAOYSA-N Y InChI=1/C10H14/c1-7-5-9(3)10(4)6-8(7)2/h5-6H,1-4H3 Key: SQNZJJAZBFDUTD-UHFFFAOYAJ
SMILES c1c(c(cc(c1C)C)C)C
Properties
Chemical formula	C10H14
Molar mass	134.21816
Density	0.868 g/cm3
Melting point	79.2 °C (174.6 °F; 352.3 K)
Boiling point	192 °C (378 °F; 465 K) at 760mmHg
Magnetic susceptibility (χ)	-101.2·10−6 cm3/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Flammable
Flash point	73.9 °C (165.0 °F; 347.0 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Production

It is a component of coal tar and was first prepared from pseudocumene in 1870.^[1] It is produced by methylation of other methylated benzene compounds such as p-xylene and pseudocumene.^[2]

C₆H₄(CH₃)₂ + 2 CH₃Cl → C₆H₂(CH₃)₄ + 2 HCl

In industry, a mixture of xylenes and trimethylbenzenes is alkylated with methanol. Durene can be separated from its isomers by selective crystallization, exploiting its high melting point.^[3] The original synthesis of durene involved a similar reaction starting from toluene.^[4]

Durene is a significant byproduct of the production of gasoline from methanol via the "MTG (Methanol to Gasoline) process".^[5]

Reactions and uses

It is a relatively easily oxidized benzene derivative, with E_1/2 of 2.03 V vs NHE.^[6] Its nucleophilicity is comparable to that of phenol.^[7] It is readily halogenated on the ring for example. Nitration gives the dinitro derivative, a precursor to duroquinone. In industry, it is the precursor to pyromellitic dianhydride, which is used for manufacturing curing agents, adhesives, coating materials. It is used in the manufacture of some raw materials for engineering plastics (polyimides) and cross-linking agent for alkyd resins.^[8] It is also a suitable starting material for the synthesis of hexamethylbenzene.^[2]

With a simple proton NMR spectrum comprising two signals due to the 2 aromatic hydrogens (2H) and four methyl groups (12H), durene is used as an internal standard.^[9]

Safety

Durene is not a skin irritant nor a skin sensitizer or eye irritant. Durene is only slightly toxic on an acute toxicologic basis and only poses an acute health hazard when ingested in excessive quantities.^[10]

References

1. Jannasch, Paul; Fittig, Rudolph (1870). "Ueber das Tetramethylbenzol" [On tetramethylbenzene]. Zeitschrift für Chemie. 6: 161–162.
2. Smith, Lee Irvin (1930). "Durene". Organic Syntheses. 10: 32. doi:10.15227/orgsyn.010.0032; Collected Volumes, vol. 2, p. 248.
3. Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter; Höke, Hartmut (2002). "Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_227. ISBN 978-3527306732.
4. Ador, E.; Rilliet, A. (1879). "Ueber durch Einwirkung von Chlormethyl auf Benzol in Gegenwart von Aluminiumchlorid erhaltene Kohlenwasserstoffe" [Hydrocarbons obtained by the action of methyl chloride on benzene in the presence of aluminum chloride]. Chem. Ber. 12: 329–332. doi:10.1002/cber.18790120191.
5. Packer, John; Kooy, P.; Kirk, C. M.; Wrinkles, Claire. "The Production of Methanol and Gasoline" (PDF). New Zealand Institute of Chemistry. Archived (PDF) from the original on September 28, 2006.
6. Howell, J. O.; Goncalves, J. M.; Amatore, C.; Klasinc, L.; Wightman, R. M.; Kochi, J. K. (1984). "Electron transfer from aromatic hydrocarbons and their pi-complexes with metals. Comparison of the standard oxidation potentials and vertical ionization potentials". Journal of the American Chemical Society. 106 (14): 3968–3976. doi:10.1021/ja00326a014.
7. Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter; Höke, Hartmut (2002). "Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a13_227. ISBN 3527306730.
8. Röhrscheid, F. (2012). "Carboxylic Acids, Aromatic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a05_249. ISBN 978-3527306732.
9. e.g. in Petr K. Sazonov, Vasyli A. Ivushkin, Galina A. Artamkina, and Irina P. Beletskaya (2003). "Metal carbonyl anions as model metal-centered nucleophiles in aromatic and vinylic substitution reactions". Arkivoc. 10: 323–334.{{cite journal}}: CS1 maint: multiple names: authors list (link)
10. Dennis W. Lynch, Vernon B. Perone, Ronald L. Schuler, William B. Ushry & Trent R. Lewis, Journal Drug and Chemical Toxicology Volume 1, 1978 - Issue 3, Pages 219-230 (2008)