| HS Code | 269682 |
| Product Name | Technical Grade Toluene |
| Chemical Formula | C7H8 |
| Cas Number | 108-88-3 |
| Ec Number | 203-625-9 |
| Un Number | 1294 |
| Molecular Weight | 92.14 g/mol |
| Appearance | Clear, colorless liquid |
| Odor | Aromatic, benzene-like |
| Boiling Point | 110.6 °C |
| Melting Point | -95 °C |
| Flash Point | 4 °C (closed cup) |
| Autoignition Temperature | 480 °C |
| Explosive Limits | 1.1–7.1 vol% in air |
| Density | 0.867 g/cm3 at 20 °C |
| Vapor Pressure | 2.9 kPa at 20 °C |
| Vapor Density | 3.14 (air = 1) |
| Solubility In Water | 0.52 g/L at 20 °C |
| Refractive Index | 1.496 at 20 °C |
| Viscosity | 0.59 mPa·s at 20 °C |
| Purity | ≥99.0% |
| Benzene Content | ≤0.1% |
| Water Content | ≤0.05% |
| Acidity | ≤0.005% as acetic acid |
| Nonvolatile Matter | ≤0.001 g/100 mL |
| Color | ≤20 Pt-Co |
As an accredited Technical Grade Toluene factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Technical Grade Toluene is supplied in 200 L steel drums, labeled flammable with UN 1294 and secure closures. |
| Container Loading (20′ FCL) | Technical Grade Toluene, UN1294, Class 3 flammable liquid, loaded in a 20′ FCL container, properly secured and labeled. |
| Shipping | Technical Grade Toluene is a flammable liquid (UN 1294, Class 3, PG II). Ship in UN-approved drums or totes with secure closures. Use flammable liquid labels/placards, provide SDS and shipping papers, and follow DOT/IMDG/IATA rules. Keep away from heat, sparks, open flames, and oxidizers. Ensure compatibility and emergency response information. |
| Storage | Store Technical Grade Toluene in a cool, dry, well-ventilated area away from heat, sparks, open flames, and oxidizing agents. Keep containers tightly closed, labeled, and upright in approved flammable-liquid storage cabinets or dedicated flammable storage rooms. Use grounded/bonded metal containers, secondary containment, and spill-control measures. Maintain firefighting equipment and ensure adequate ventilation. Protect from direct sunlight and incompatible materials. |
| Shelf Life | Technical grade toluene has an indefinite shelf life when stored in sealed containers away from heat, light, and ignition sources. |
Technical-grade toluene is fed to di-isocyanate supply chains after a two-stage nitration sequence with mixed acid. The feedstock specification is not governed solely by ASTM D841; downstream nitration units impose stricter benzene and sulfur ceilings because benzene nitrates to nitrobenzene and sulfur poisons hydrogenation catalysts. A common procurement limit for benzene is 0.05 mass %, with total sulfur below 1 mg/kg, although exact values are set by site-specific catalyst warranties. The first nitration stage produces mononitrotoluene, and the second stage converts the para-rich nitrotoluene stream to dinitrotoluene. Under adiabatic mixed-acid conditions, the 2,4-dinitrotoluene mass fraction typically falls within 0.76–0.82, while 2,6-dinitrotoluene accounts for 0.18–0.24. The isomer ratio is kinetically and thermodynamically controlled by sulfuric acid strength and the temperature profile across the nitrator loop. Excessive first-stage residence time increases ortho-nitrotoluene by-products that lower downstream diamine purity. Crude dinitrotoluene is washed with water and alkali to remove residual nitrate and sulfate species; incomplete acid removal shortens supported nickel catalyst life in the hydrogenation stage. Hydrogenation of dinitrotoluene to toluene diamine is performed in a continuous slurry or fixed-bed reactor with a supported nickel catalyst. Temperature is typically held between 120 °C and 180 °C, and hydrogen partial pressure is maintained between 1 MPa and 10 MPa depending on reactor type. The phosgenation stage uses o-dichlorobenzene or monochlorobenzene as the reaction medium, and the crude TDI is purified by vacuum distillation to produce the 80/20 and 65/35 isomer blends used in flexible slabstock foam and coatings. Terminal slabstock foams are processed at isocyanate indices from 100 to 115, where index shifts adjust hardness and load-bearing without changing cell gas composition. Compliance obligations concentrate on ATEX 2014/34/EU for nitration and hydrogenation areas, REACH (EC) No 1907/2006 for toluene and TDI, and the United States OSHA 8-hour permissible exposure limit for toluene of 200 ppm.
Aromatics complexes operating toluene disproportionation and transalkylation consume technical-grade toluene as a balance stream to shift output toward benzene and mixed xylenes. The fixed-bed reactor contains a zeolitic catalyst and operates at 400–500 °C, 1–3 MPa, and a hydrogen-to-hydrocarbon molar ratio of 3:1–10:1. Hydrogen cofeed is maintained because coke selectivity rises sharply when the reactor inlet temperature exceeds the upper end of the window. Feed toluene is specified not only by ASTM D841 but also by low nitrogen and carbonyl content, because basic nitrogen neutralizes acidic sites and oxygenates add hydrogen consumption. In a typical integrated aromatics complex, the transalkylation effluent is separated in a reformate splitter and an extractive distillation column. The benzene fraction must satisfy ASTM D2359 for refined benzene before entering cumene or ethylbenzene units. The mixed xylene fraction is routed to adsorption or crystallization-based para-xylene recovery under ASTM D5211 feedstock tolerances for C8 composition and ethylbenzene content. The terminal outputs include styrene, cumene-based phenol, and purified terephthalic acid. The fixed-bed pressure drop and catalyst coke make gas recycle compressor load the main process constraint. Coke formation is controlled by keeping the hydrogen-to-hydrocarbon ratio above 4:1 and limiting the final boiling point of the C9 aromatic feed. End-product benzene and xylene purity are verified by gas chromatography against the established ASTM specification limits for benzene and xylene feedstock.
Technical-grade toluene is oxidized in the liquid phase with air in a bubble column or mechanically agitated gas-liquid reactor. The catalyst is a homogeneous cobalt or cobalt/manganese acetate system, with total metal content in the reaction mixture usually between 10 mg/kg and 500 mg/kg by mass. Reaction temperature is controlled at 140–160 °C, and total pressure is set at 0.3–0.6 MPa to maintain oxygen transfer without entering the flammable regime. The conversion per pass is deliberately kept in the 30–40 mass % range to suppress benzyl alcohol and benzaldehyde intermediates. Selectivity to benzoic acid above 95 mass % is obtained at the lower conversion bound. Off-gas oxygen concentration is monitored continuously and kept below 8 vol % in the condenser vent, because oxidation units have an upper flammability boundary that is a function of toluene concentration and operating temperature. The crude benzoic acid is recovered by pressure crystallization or distillation from the unreacted toluene recycle stream. The terminal products include sodium benzoate, benzoate ester plasticizers, and phenol via oxidative decarboxylation. Sodium benzoate used as a food preservative is subject to 21 CFR 184.1733, but that specification is imposed after the toluene-derived benzoic acid is purified and not at the oxidation reactor. The oxidation mother liquor contains heavy benzyl benzoate and tar. If the tar concentration is allowed to exceed 2 mass % of the reactor liquid, heat transfer fouling on internal coils becomes measurable as a rise in coolant demand. This application has a narrower operating window than solvent use because the reaction exotherm is coupled to oxygen partial pressure.
In coil-coating and flexographic ink formulation, technical-grade toluene is used where a high evaporation rate and a solvency window for acrylic, polystyrene, and chlorinated rubber resins are required. The Hansen solubility parameters of toluene are δD 18.0 MPa0.5, δP 1.4 MPa0.5, and δH 2.0 MPa0.5, which place it inside the solubility sphere of most styrene-acrylate copolymers. The evaporation rate is approximately 2.0 relative to n-butyl acetate, and the closed-cup flash point is near 4 °C. Solvent-handling areas must therefore be designed to ATEX 2014/34/EU. Formulation viscosity is adjusted with toluene at letdown in a high-shear disperser, but the final flash-off profile in a spray booth is set by the combination of boiling range and air velocity. For a coil-coating line, the peak metal temperature and residence time in the curing oven are tuned to keep the solvent dew point below the oven lower explosive limit. The formulation must comply with the volatile organic compound limits of EU Directive 2004/42/CE, and VOC content is measured according to ASTM D3960 in the United States. Terminal products include automotive refinish solvents, flexographic and gravure inks, and neoprene-based contact cements. This solvent application does not transfer into pharmaceutical or food-contact processes unless a separate high-purity toluene grade is qualified. Batch-to-batch viscosity drift in production is tied to residual water content. If the toluene contains free water above saturation, resin precipitation in the letdown tank appears as filter-blocking gel particles.
The replacement of xylene with technical-grade toluene in a polyesterification cook changes azeotropic water removal. The reactor is charged with polyol, fatty acid, and dibasic acid, then heated to 220–240 °C as reflux solvent is returned from a Dean-Stark separator. Toluene's lower boiling point reduces the reflux vapor temperature by approximately 28 °C relative to mixed xylene, which slows esterification rate unless the reactor is run with a higher solvent return flow. A typical solvent charge is 5–10 mass % of the reactor batch. The toluene-water azeotrope boils at about 84 °C and returns from the separator as a toluene-rich upper layer. The water draw-off rate from the Dean-Stark trap is used as a process control indicator; if the draw-off rate drops while acid value remains unchanged, the reactor charge is checked for wet toluene or a blocked condenser. Terminal products are alkyd resins for air-dried and baked industrial paints. The cook unit vent is routed to a thermal oxidizer, and total VOC emissions are governed by local permit limits that reference ASTM D3960 or equivalent national methods. Toluene retained in the final alkyd resin must be accounted for in the coating formulation's volatile organic compound content.
Technical-grade toluene entering the motor gasoline pool is used as a high-octane aromatic blendstock. The research octane number of toluene is approximately 121, the motor octane number is near 107, and the density at 15 °C is 0.867 g/cm³. These properties make toluene a premium component for reformulated gasoline, but the finished fuel must satisfy ASTM D4814 in the United States and EN 228 in the European Union. Total aromatics in the finished product are capped by regulation in many regions. Gasoline with excessive toluene contributes to high final boiling point and can raise T90 distillation temperature. The blending ratio is limited less by toluene purity and more by the final vapor pressure, distillation index, and aromatics cap. In a refinery gasoline pool, toluene content above 25 vol % can force an increase in light straight-run naphtha or isomerate to correct the distillation slope. The terminal product is an EN 228-compliant grade of E5 or E10 gasoline, where toluene is one of several aromatics selected to meet octane targets without exceeding the oxygen content set for ethanol blending. Fuel-grade terminal operations are governed by tank farm vapor recovery and sulfur specification. Technical-grade toluene with benzene below 0.05 mass % helps avoid benzene credit constraints, but the final benzene limit is regulated at the finished fuel level.
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Technical Grade Toluene, product code TOL-TG-99.0, is a clear, water-white aromatic hydrocarbon liquid with CAS registry number 108-88-3, EC number 203-625-9, and relative molecular mass 92.14 g/mol. The material is supplied against a representative release specification of 99.0 wt% minimum toluene purity by capillary gas chromatography, 0.10 wt% maximum benzene, 0.50 wt% maximum non-aromatic hydrocarbons, 1.0 mg/kg maximum total sulfur, 0.02 wt% maximum water, and a distillation range at 101.3 kPa from 110.5 °C to 111.0 °C. Density at 20 °C is specified as 0.865–0.870 g/cm³ and platinum-cobalt colour is controlled to 10 maximum under ASTM D1209. The product is not sold as a certified reference material; trace-level olefins, thiophenes, and carbonyl compounds may be present at or below the release limits shown in the specification matrix. Model code TOL-TG-99.0 designates a technical-grade material intended for industrial chemical conversion, solvent formulation, and process extraction where nitration-grade certification or ACS reagent-grade documentation is not required.
| Parameter | Release limit | Analytical method |
|---|---|---|
| Toluene purity | 99.0 wt% min | ASTM D6526 |
| Benzene | 0.10 wt% max | ASTM D6526 |
| Non-aromatic hydrocarbons | 0.50 wt% max | ASTM D6526 |
| Total sulfur | 1.0 mg/kg max | ASTM D5453 |
| Water | 0.02 wt% max | ASTM E1064 |
| Distillation range at 101.3 kPa | 110.5–111.0 °C | ASTM D1078 |
| Density at 20 °C | 0.865–0.870 g/cm³ | ASTM D4052 |
| Colour, Pt-Co | 10 max | ASTM D1209 |
| Acidity as acetic acid | 0.005 wt% max | ASTM D847 |
| Non-volatile residue | 0.001 wt% max | ASTM D1353 |
The principal product differentiator is the control of benzene, total sulfur, olefins, and distillation range. Nitration-grade toluene, commonly released against ASTM D841-19, is restricted to benzene concentrations at or below 0.05 wt% and total sulfur at or below 0.5 mg/kg in many supply agreements because benzene nitrates to nitrobenzene during mixed-acid nitration of toluene to mononitrotoluene, and sulfur compounds increase spent-acid treatment loads and stabilise interfacial emulsions in the nitrator separator. Technical-grade TOL-TG-99.0 permits benzene up to 0.10 wt% and sulfur up to 1.0 mg/kg, which is acceptable for many solvent and chemical intermediate uses but not automatically acceptable for dinitrotoluene producers without feed verification. Reagent-grade toluene is controlled for spectrophotometric transparency, non-volatile residue, and water at levels that are unnecessary for bulk conversion, and it is normally packaged in smaller glass or lined metal containers rather than bulk railcars.
| Parameter | Technical grade TOL-TG-99.0 | Nitration grade ASTM D841-19 | ACS reagent grade |
|---|---|---|---|
| Toluene purity, min | 99.0 wt% | 99.0 wt% | 99.5 wt% |
| Benzene, max | 0.10 wt% | 0.05 wt% | 0.05 wt% |
| Total sulfur, max | 1.0 mg/kg | 0.5 mg/kg | ACS sulfur-compound test |
| Water, max | 0.02 wt% | 0.02 wt% | 0.03 wt% |
| Distillation range | 110.5–111.0 °C | 1.0 °C max incl 110.6 °C | 1.0 °C max incl 110.6 °C |
| Colour Pt-Co, max | 10 | 10 | 10 |
| Non-volatile residue, max | 0.001 wt% | 0.001 wt% | 0.001 wt% |
In toluene disproportionation units, the feedstock is vaporised and preheated to 390–450 °C before entering a fixed-bed reactor charged with a shape-selective MFI-type zeolite catalyst. At reactor outlet pressures of 1.5–2.5 MPa and hydrogen-to-hydrocarbon molar ratios of 2.0–4.0, the equilibrium-limited conversion produces benzene and mixed xylenes. Non-aromatic hydrocarbons in technical-grade toluene, even at the 0.50 wt% maximum release limit, can concentrate in the benzene overhead stream; benzene purity of 99.9 wt% is achieved only when the distillation train is equipped with a side-draw benzene column and an aromatics extraction stage. Published data for this specific configuration is limited.
Hydrodealkylation to benzene operates at higher severity, typically 550–650 °C and 3.5–7.0 MPa hydrogen partial pressure over chromia-alumina catalysts. Total sulfur in the feed above 1.0 mg/kg is removed by a hydrodesulfurization guard bed because sulfur compounds poison the metal function of downstream reforming catalysts. For nitration to mononitrotoluene, a technical-grade feed containing 0.10 wt% benzene will form nitrobenzene at a rate proportional to benzene concentration, increasing the distillation load for mononitrotoluene purification and creating a separate nitrobenzene stream that must be handled under the same thermal runaway constraints as the main nitration reaction.
In solvent-borne alkyd systems, toluene functions as a viscosity-reducing diluent with a Hansen solubility parameter set of δD = 18.0 MPa^1/2, δP = 1.4 MPa^1/2, and δH = 2.0 MPa^1/2. Its relative evaporation rate, referenced to n-butyl acetate = 1.0 under ASTM D3539, is approximately 2.0. This provides early flash-off in spray-applied coatings but raises the risk of solvent popping and gloss reduction at wet film thicknesses above 60 µm when booth temperature exceeds 35 °C. Liquid viscosity at 20 °C is 0.59 mPa·s, and surface tension is 28.4 mN/m, which supports wetting of steel substrates with surface energies above 40 mN/m.
Side-chain oxidation to benzoic acid is carried out with air or oxygen at 140–160 °C and 0.5–1.0 MPa in the presence of cobalt and manganese acetate catalysts. The methyl group of toluene is selectively oxidised, while benzene in the feed above 0.10 wt% is only minimally oxidised and accumulates in the recycle gas, reducing reactor productivity. This is a practical reason for tight benzene control even in applications that do not require nitration-grade material.
For low-temperature industrial maintenance coatings, toluene is selected over benzene because benzene has a freezing point of 5.5 °C, whereas toluene remains liquid down to −95 °C. This property, combined with a boiling point of 110.6 °C at 101.3 kPa, permits storage and application in unheated spray sheds without in-line heat tracing. However, toluene is classified under CLP as Flam. Liq. 2 H225, Repr. 2 H361d, Asp. Tox. 1 H304, STOT RE 2 H373, Skin Irrit. 2 H315, Eye Irrit. 2 H319, and Aquatic Chronic 3 H412. The EU 8-hour occupational exposure limit is 50 ppm (192 mg/m³) and the short-term limit is 100 ppm (384 mg/m³) under Directive 2009/161/EU; the ACGIH TLV-TWA is 20 ppm. Substitution therefore requires forced ventilation, closed transfer, and cartridge respirators with AX type vapour filters during spray application.
Relative to mixed xylenes, technical-grade toluene boils at 110.6 °C versus 138–144 °C for the mixed isomer blend. The lower boiling range produces faster release from lacquer films but increases VOC capture load at the oven; in coil-coating lines with thermal oxidisers, solvent loading must be limited to keep the lower explosive limit below 25% inside the oven. Relative to benzene, toluene has a higher methyl side-chain reactivity, supporting selective oxidation to benzoic acid and photochlorination to benzyl chloride under controlled free-radical conditions.
Storage tanks for technical-grade toluene are constructed from carbon steel and are designed with nitrogen blanketing to maintain an oxygen concentration below 8 vol% at the vapour surface. The lower flammability limit is 1.1 vol%, the upper flammability limit is 7.1 vol%, the flash point is 4.4 °C closed cup under ASTM D56, and the autoignition temperature is 480 °C. Vents are sized to API 2000 for pump-in and thermal outbreathing. Transfer pumps are specified with mechanical seals and wetted parts in polytetrafluoroethylene or polyvinylidene fluoride because toluene swells nitrile and EPDM elastomers beyond 10 vol% after 72 h immersion at 40 °C. Loading arms require vapour-recovery devices to avoid release of a volatile organic compound with a vapour pressure of 2.9 kPa at 20 °C, and separation from oxidising agents, nitric acid, chlorates, and peroxides is mandatory because toluene forms heat-sensitive nitration and oxidation products.
In flexographic printing ink systems, technical-grade toluene is used as a letdown solvent to adjust press-ready viscosity to 18–22 s in a 4 mm DIN flow cup at 23 °C. Aliphatic hydrocarbon content above 0.50 wt% after solvent recovery will reduce resin solubility and can produce ink body separation. Solvent recovery systems using activated carbon adsorption followed by steam desorption return toluene at 99.0 wt% minimum only when the desorbate is dried and redistilled; otherwise water content above 0.10 wt% causes pinholes and poor ink transfer on polyethylene film. This is an operational boundary, not a specification failure of the virgin product.
In pharmaceutical and agricultural extraction, technical-grade toluene is used as a process solvent for non-aqueous reactions requiring a water-immiscible aromatic phase. The partition coefficient log Kow of 2.73 and water solubility of 0.52 g/L at 20 °C define the phase-transfer limitations. Residual solvent in finished active pharmaceutical ingredients is controlled under ICH Q3C; toluene is a Class 2 solvent with a permitted daily exposure of 8.9 mg/day and a concentration limit of 890 ppm in drug substances. Technical-grade material can be used only when subsequent purification removes trace olefins and sulfur compounds to meet the final residual solvent monograph.
Batch release employs capillary gas chromatography under ASTM D6526 for purity and trace impurities. Water is determined by coulometric Karl Fischer titration under ASTM E1064, total sulfur by ultraviolet fluorescence under ASTM D5453, distillation range by ASTM D1078, density by ASTM D4052, acidity by ASTM D847, and non-volatile residue by ASTM D1353. Each lot must be accompanied by a certificate of analysis showing actual numerical results, not only maximum release limits, to allow downstream disproportionation or nitration operators to calculate catalyst poison loading and to verify compliance with REACH Annex XVII entry 48 when the substance is used in adhesives or spray paints intended for supply to the general public.
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