1,2,3-Trimethylbenzene

1,2,3-Trimethylbenzene is an organic compound with the chemical formula C₆H₃(CH₃)₃. Classified as an aromatic hydrocarbon, it is a flammable colorless liquid. It is nearly insoluble in water but soluble in organic solvents.

1,2,3-Trimethylbenzene

Names
Preferred IUPAC name 1,2,3-Trimethylbenzene
Other names Hemellitol; Hemimellitol, Hemimelithol; Hemimellitine; Hemimellitene
Identifiers
CAS Number	526-73-8 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1903410
ChEBI	CHEBI:34037 Y
ChEMBL	ChEMBL1797279
ChemSpider	10236 Y
ECHA InfoCard	100.007.633
EC Number	208-394-8
Gmelin Reference	326517
PubChem CID	10686
RTECS number	DC3300000
UNII	ZK4R7UPH6R Y
UN number	1993
CompTox Dashboard (EPA)	DTXSID8047769
InChI InChI=1S/C9H12/c1-7-5-4-6-8(2)9(7)3/h4-6H,1-3H3 Y Key: FYGHSUNMUKGBRK-UHFFFAOYSA-N Y InChI=1S/C9H12/c1-7-5-4-6-8(2)9(7)3/h4-6H,1-3H3
SMILES c1(cccc(c1C)C)C
Properties
Chemical formula	C9H12
Molar mass	120.195 g·mol−1
Appearance	Colorless liquid[1]
Density	0.89 g/mL[1]
Melting point	−25 °C (−13 °F; 248 K)[1]
Boiling point	176 °C (349 °F; 449 K)[1]
Solubility in water	0.006% (20°C)[2]
Vapor pressure	1 mmHg (16.7°C)[2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Flammable[3]
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H226, H315, H319, H335
Precautionary statements	P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P370+P378, P403+P233, P403+P235, P405, P501
Flash point	11 °C; 51 °F; 284 K[1]
Autoignition temperature	243 °C; 470 °F; 516 K[1]
Explosive limits	0.8%-6.6%[2]
NIOSH (US health exposure limits):
PEL (Permissible)	none[2]
REL (Recommended)	TWA 25 ppm (125 mg/m3)[2]
IDLH (Immediate danger)	N.D.[2]
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

The compound occurs naturally in coal tar and petroleum. It is one of the three isomers of trimethylbenzene. It is used in jet fuel, mixed with other hydrocarbons, to prevent the formation of solid particles which might damage the engine.

German chemist Oscar Jacobsen [de] first prepared the hydrocarbon in 1882 and designated it hemellitol as a reference to the trivial name of hexamethylbenzene.^[4] Four years later he also discovered it in the coal tar.^[5]

Production

Industrially, it is isolated from the C₉ aromatic hydrocarbon fraction during petroleum distillation. It is also generated by methylation of toluene and xylenes.^[6]

References

1. Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
2. NIOSH Pocket Guide to Chemical Hazards. "#0637". National Institute for Occupational Safety and Health (NIOSH).
3. CDC - NIOSH Pocket Guide to Chemical Hazards
4. Jacobsen, Oscar (1882). "Ueber Isodurol, Isodurylsäuren und das dritte Trimethylbenzol". Berichte der deutschen chemischen Gesellschaft. 15 (2): 1853–1858. doi:10.1002/cber.18820150292. ISSN 0365-9496.
5. Jacobsen, Oscar (1886). "Beitrag zur Kenntniss der zwischen 170 und 200° siedenden Kohlenwasserstoffe des Steinkohlentheeröls". Berichte der deutschen chemischen Gesellschaft. 19 (2): 2511–2515. doi:10.1002/cber.188601902195. ISSN 0365-9496.
6. Karl Griesbaum, Arno Behr, Dieter Biedenkapp, Heinz-Werner Voges, Dorothea Garbe, Christian Paetz, Gerd Collin, Dieter Mayer, Hartmut Höke "Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry 2002 Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_227