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Mesitylene Basic information

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Mesitylene Chemical Properties

Melting point:
-45 °C
Boiling point:
163-166 °C(lit.)
0.864 g/mL at 25 °C(lit.)
vapor density 
4.1 (vs air)
vapor pressure 
14 mm Hg ( 55 °C)
refractive index 
n20/D 1.499(lit.)
Flash point:
112 °F
storage temp. 
Miscible with alcohol, benzene, ether (Windholz et al., 1983), and trimethylbenzene isomers.
>14 (Schwarzenbach et al., 1993)
Clear colorless
explosive limit
0.88-6.1%, 100°F
Odor Threshold
Water Solubility 
2.9 g/L (20 ºC)
Henry's Law Constant
4.03, 4.60, 5.71, 6.73, and 9.63 at 10, 15, 20, 25, and 30 °C, respectively (EPICS, Ashworth et al.,1988)
Exposure limits
NIOSH REL: TWA 25 ppm (125 mg/m3); ACGIH TLV: TWA for mixed isomers 25 ppm (adopted).
Stable. Combustible. Incompatible with strong oxidizing agents.
CAS DataBase Reference
108-67-8(CAS DataBase Reference)
NIST Chemistry Reference
Benzene, 1,3,5-trimethyl-(108-67-8)
EPA Substance Registry System
1,3,5-Trimethylbenzene (108-67-8)

Safety Information

Hazard Codes 
Risk Statements 
Safety Statements 
UN 2325 3/PG 3
WGK Germany 
Autoignition Temperature
1022 °F
Hazard Note 
HS Code 
Hazardous Substances Data
108-67-8(Hazardous Substances Data)
LD50 (inhalation) for rats 24 g/m3/4-h (quoted, RTECS, 1985).



Mesitylene Usage And Synthesis


The molecular structure of mesitylene (also known as mesitylene, molecular formula is C9H12) is σ bond which formed by benzene ring C atoms by means of sp2 hybrid orbital, other C atoms form σ bond by means of sp3 hybrid orbital, it is functional group in the presence of many multi organic compounds. It is aromatic hydrocarbon which obtained by three hydrogens symmetrically-substituted by three methyl in benzene ring.It is widespread in coal tar and certain petroleum. It is colorless liquid, toxic, flammable and explosive. The freezing point is-44.72 ℃, melting point is-44.7 ℃, boiling point is 164.7 ℃, the relative density is 0.8652 (20/4℃). Mesitylene can generate trimesic acid with the oxidation of dilute nitric acid. Pure mesitylene is made by acetone in vapor phase catalytic dehydrationthe at 300~500℃.
Mesitylene is important organic chemical raw material, the use of mesitylene can develop three toluene, trimesic acid, benzoic anhydride and other dye intermediates, it can also be used for the production of antioxidants, polyester resin curing agent, stabilizer, alkyd resins and plasticizers. Since mesitylene is a good solvent, and it is flammable, irritant, and it has low freezing point. In the electronics industry, it is used as developer of photosensitive sheet silicone.
Mesitylene is also common volatile organic compound (VOC) in city, this is mainly generated by the combustion. It plays an important role (including aerosol and tropospheric ozone generation) in many chemical reactions in the atmosphere. Since the three hydrogens on the aromatic ring have the same chemical environment, in the mesitylene magnetic resonance spectrum hydrogen spectrum only has a single peak which peak area is corresponding to three hydrogen in the vicinity of 6.8ppm. Therefore, mesitylene is sometimes used as internal standard substance in proton nuclear magnetic resonance method which comprises aromatic organic samples.
The annual demand of mesitylene is about 100,000 tons in current domestic market.
The above information is edited by the chemicalbook of Wang Xiaodong.

Chemical Properties

It is colorless transparent liquid. It is insoluble in water, soluble in ethanol, it can dissolve in benzene, ether, acetone in any proportion.


It can be used for the production of trimesic acid and antioxidants, epoxy curing agents, stabilizers polyester resin, alkyd resin, plasticizers and dyes etc.
It can be used as raw material of organic synthesis, it can be used in the preparation of trimesic acid, and antioxidants, epoxy curing agents, stabilizers polyester resin, alkyd resin, plasticizer, 2,4,6-trimethyl aniline reactive brilliant blue, K-3R and other dye.
It can be used as analytical reagents, solvents, it can be also used in organic synthesis, etc.

Production method

1. It is derived by the separation of C9 aromatic hydrocarbon. 2. In the reforming of heavy aromatics the amount of mesitylene is about 11.8%. However, due to its boiling point (164.7 ℃) is extremely close to the boiling point of O-methyl benzene (165.15 ℃), it is difficult to separate for using distillation method. 3.The isomerization method with partial three toluene as raw material can fractionate, and can get mesitylene which the one way yield is 21.6%, the purity is more than 95%, while 4%-7% of by-product is durene, xylene is 9%. The average temperature of reactor bed is 260℃, pressure is 2.35MPa, empty the entire is 1.0h-1, molar ratio of reforming hydrogen and oil is 10: 1, the catalyst is mordenite which lack of aluminum hydrogen form: Cu: Ni: binder = 85.2: 0.5: 15. Under these conditions, the conversion rate of partial three toluene is 46%, selectivity is 47% , one way yield of mesitylene is 21.6%. HF-BF3 is xylene separated and through the method of isomerization by Japanese Mitsubishi Gas Company, by-products contain high concentration of mesitylene of high boiling, the goods can be get by distilled and refined. 4. Acetone in sulfuric acid-catalyzed goes through dehydration synthesis can obtain this goods with the yield of 13%-15%. 4600g (79mol) of industrial acetone is cooled to 0-5℃, and 4160ml concentrated sulfuric acid is added with stirring, the temperature can not exceed 10℃. After addition is completed, cntinue stirring 3-4h, place at room temperature for 18-24h. The product is subjected to steam distillation, mesitylene is separated, then it is washed with alkali, water, and then collect distillation fraction of 210℃, 15g sodium metal is added into this fraction, it is heated to near the boiling point, 2/3 liquid is evaporated. the residue is distilled to 210℃, efficient fractionation collection is done for the 163-167℃ distillate, 430-470g1,3,5-mesitylene can be obtained.


It is flammable liquid.

Toxicity grading

Low toxicity.

Acute toxicity

Inhalation-rat LC50: 24000 mg/m/4 hours.

Stimulus data

Skin-Rabbit 20 mg/24 hours of moderate; Eyes-rabbit 500 mg/24 hr mild.

Flammability hazard characteristics

It is inflammable in case of fire, heat, oxidants; when burning stimulated smoke can generate.

Storage characteristics

Treasury should have ventilation and be low-temperature drying; and it should stored separately with oxidants.

Extinguishing agent

Dry powder, dry sand, carbon dioxide, foam, 1211 fire extinguishing agent.

Professional standards

TWA 120 mg/m³; STEL 170 mg/m.

Chemical Properties

colourless liquid with an aromatic odour

Chemical Properties

Mesitylene is a clear, colorless liquid. Distinctive, aromatic odor.

Physical properties

Colorless liquid with a peculiar odor. An odor threshold concentration of 170 ppbv was reported by Nagata and Takeuchi (1990).


Intermediate, including anthraquinone vat dyes, UV oxidation stabilizers for plastics.


ChEBI: A trimethylbenzene carrying methyl substituents at positions 1, 3 and 5.

Synthesis Reference(s)

Journal of the American Chemical Society, 92, p. 3232, 1970 DOI: 10.1021/ja00713a078
The Journal of Organic Chemistry, 19, p. 923, 1954 DOI: 10.1021/jo01371a008

General Description

A colorless liquid with a peculiar odor. Insoluble in water and less dense than water. Flash point near 123°F. May be toxic by ingestion and inhalation. Used to make plastics and dyes.

Air & Water Reactions

Flammable. Insoluble in water.

Reactivity Profile

TRIMETHYLBENZENE is incompatible with the following: Oxidizers, nitric acid .


Moderate fire hazard. Toxic by inhalation. Central nervous system impairment, asthma, and hematologic effects.

Health Hazard

May cause toxic effects if inhaled or absorbed through skin. Inhalation or contact with material may irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.

Fire Hazard

HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

Safety Profile

Poison by inhalation. Moderately toxic by intraperitoneal route. Human systemic effects by inhalation: sensory changes involving peripheral nerves, somnolence (general depressed activity), and structural or functional change in trachea or bronchi. Reports of leukopenia and thrombocytopenia in experimental animals. A mild skin and eye irritant. A flammable liquid when exposed to heat or flame; can react vigorously with oxidizing materials. Violent reaction with HNO3. To fight fire, use water spray, fog, foam, CO2. Emitted from modern buildmg materials (CENEAR 69,22,91). When heated to decomposition it emits acrid smoke and irritating fumes.

Potential Exposure

Mesitylene is used as raw material in chemical synthesis and as ultraviolet stabilizer; as a paint thinner, solvent, and motor fuel component; as an intermediate in organic chemical manufacture.


Detected in distilled water-soluble fractions of 87 octane gasoline (0.34 mg/L), 94 octane gasoline (1.29 mg/L), Gasohol (0.48 mg/L), No. 2 fuel oil (0.08 mg/L), jet fuel A (0.09 mg/L), diesel fuel (0.03 mg/L), and military jet fuel JP-4 (0.09 mg/L) (Potter, 1996). Schauer et al. (1999) reported 1,3,5-trimethylbenzene in a diesel-powered medium-duty truck exhaust at an emission rate of 260 μg/km.
California Phase II reformulated gasoline contained 1,3,5-trimethylbenzene at a concentration of 7.45 g/kg. Gas-phase tailpipe emission rates from gasoline-powered automobiles with and without catalytic converters were 1.98 and 210 mg/km, respectively (Schauer et al., 2002).
Thomas and Delfino (1991) equilibrated contaminant-free groundwater collected from Gainesville, FL with individual fractions of three individual petroleum products at 24–25 °C for 24 h. The aqueous phase was analyzed for organic compounds via U.S. EPA approved test method 602. Average 1,3,5-trimethylbenzene concentrations reported in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were 333, 86, and 13 μg/L, respectively. When the authors analyzed the aqueous-phase via U.S. EPA approved test method 610, average 1,3,5- trimethylbenzene concentrations in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were greater, i.e., 441, 91, and 27 μg/L, respectively.
Drinking water standard: No MCLGs or MCLs have been proposed (U.S. EPA, 2000).

Environmental Fate

Biological. In anoxic groundwater near Bemidji, MI, 1,3,5-trimethylbenzene anaerobically biodegraded to the intermediate tentatively identified as 3,5-dimethylbenzoic acid (Cozzarelli et al., 1990).
Photolytic. Glyoxal, methylglyoxal, and biacetyl were produced from the photooxidation of 1,3,5-trimethylbenzene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of 1,3,5-trimethylbenzene and OH radicals at room temperature was 4.72 x 10-11 cm3/molecule?sec (Hansen et al., 1975). A rate constant of 2.97 x 10-8 L/molecule?sec was reported for the reaction of 1,3,5-trimethylbenzene with OH radicals in the gas phase (Darnall et al., 1976). Similarly, a room temperature rate constant of 6.05 x 10-11 cm3/molecule?sec was reported for the vapor-phase reaction of 1,3,5-trimethylbenzene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 3.87 x 10-11 cm3/molecule?sec was reported for the same reaction (Ohta and Ohyama, 1985).
Chemical/Physical. 1,3,5-Trimethylbenzene will not hydrolyze because it does not contain a hydrolyzable functional group (Kollig, 1993).


UN1993 Flammable liquids, n.o.s., Hazard Class: 3; Labels: 3-Flammable liquid, Technical Name Required.

Purification Methods

Dry it with CaCl2 and distil it from Na in a glass helices-packed column. Treat it with silica gel and redistil it. Alternative purifications include vapour-phase chromatography, or fractional distillation followed by azeotropic distillation with 2-methoxyethanol (which is subsequently washed out with H2O), drying and fractional distilling. More exhaustive purification uses sulfonation by dissolving in two volumes of conc H2SO4, precipitating with four volumes of conc HCl at 0o, washing with conc HCl and recrystallising from CHCl3. The mesitylene sulfonic acid is hydrolysed with boiling 20% HCl and steam distilled. The separated mesitylene is dried (MgSO4 or CaSO4) and distilled. It can also be fractionally crystallised from the melt at low temperatures. [Beilstein 5 IV 1016.]


Vapors forms explosive mixture with air. Violent reaction with nitric acid. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides

Waste Disposal

Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed.



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Basic information Outline Chemical Properties Uses Production method Category Toxicity grading Acute toxicity Stimulus data Flammability hazard characteristics Storage characteristics Extinguishing agent Professional standards Safety Related Supplier