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| Names | |||
|---|---|---|---|
| Preferred IUPAC name 1,2,4-Trimethylbenzene | |||
| Other names Pseudocumene, Asymmetrical trimethylbenzene, ψ-Cumene | |||
| Identifiers | |||
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3D model (JSmol) | |||
| 1903005 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.002.216 | ||
| EC Number |
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| KEGG |
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| RTECS number |
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| UNII | |||
| UN number | 1993 2325 | ||
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| Properties | |||
| C9H12 | |||
| Molar mass | 120.19 g/mol | ||
| Appearance | Colorless liquid | ||
| Density | 0.8761 g/cm3 | ||
| Melting point | −43.78 °C (−46.80 °F; 229.37 K) | ||
| Boiling point | 169 to 171 °C (336 to 340 °F; 442 to 444 K) | ||
| −101.6·10−6 cm3/mol | |||
| Hazards | |||
| GHS labelling: | |||
   | |||
| Warning | |||
| H226,H315,H319,H332,H335,H411 | |||
| P210,P233,P240,P241,P242,P243,P261,P264,P271,P273,P280,P302+P352,P303+P361+P353,P304+P312,P304+P340,P305+P351+P338,P312,P321,P332+P313,P337+P313,P362,P370+P378,P391,P403+P233,P403+P235,P405,P501 | |||
| Flash point | 44.4 °C (111.9 °F; 317.5 K) | ||
| Explosive limits | 0.9%–6.4%[2] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | none[2] | ||
| Safety data sheet (SDS) | Sigma-Aldrich MSDS | ||
| Related compounds | |||
Related compounds | 1,2,3-Trimethylbenzene;1,3,5-Trimethylbenzene | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
1,2,4-Trimethylbenzene, also known aspseudocumene, is anorganic compound with the chemical formula C6H3(CH3)3. Classified as anaromatic hydrocarbon, it is a flammable colorless liquid with a strong odor. It is nearly insoluble in water but soluble in organic solvents. It occurs naturally incoal tar andpetroleum (about 3%). It is one of the threeisomers oftrimethylbenzene.
In 1849,Charles Blachford Mansfield rectifiedcoal tar and identified fractions which he hypothesized to becumole andcymole. The latter fraction boiled slightly above 170°C and had specific density of 0.857.[3]
In 1862,Warren De la Rue and Hugo Müller (1833-1915) proposed the termpseudocumole for the fractions heavier thanxylole.[4]
When three years later American chemistCyrus Warren (1824-1891) attempted to reproduce Mansfield's results, he determined that the oil boiling at 170° has the same formula as cumole, not cymole, and suggested to name itisocumole.[5]
The structure of the compound was determined by Th. Ernst andWilhelm Rudolph Fittig, who first prepared it frombromoxylene andiodomethane in 1866 by aWurtz–Fittig reaction developed two years earlier.[6]
In the next year, Fittig et al. adopted the pseudocumol terminology,[7] in 1869 Fittig and B. Wackenroder proved that the fraction is a mixture ofmesitylene with another trimethylbenzene, for which the name of pseudocumol was retained,[8] and in 1886Oscar Jacobsen [de] showed that thethird trimethylbenzene he discovered earlier is also present.[9]
Industrially, it is isolated from the C9aromatic hydrocarbon fraction duringpetroleum distillation. Approximately 40% of this fraction is 1,2,4-trimethylbenzene. It is also generated by methylation of toluene and xylenes and thedisproportionation of xylene over aluminosilicate catalysts.[10]
Pseudocumene is a precursor totrimellitic anhydride, from which high performance polymers are made. It is also used as a sterilizing agent and in the making of dyes, perfumes and resins. Another use is as anantiknock agent,[11] since its research and motoroctane numbers are well above 100.[12]: Fig. II.1 [13]
In automobile fuel it is a minor additive, with its share in USgasoline rising from 0.03–0.5% in early 1990s[14] to 1.1–2.6% in 2011.[15] It may be a major component of someavgas formulations.[16]
1,2,4-Trimethylbenzene dissolved inmineral oil is used as a liquidscintillator[17] in particle physics experiments such asNOνA andBorexino.
