2,5,6-Trimethyl-1,3-Benzothiazole
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HS Code |
688067 |
| Chemical Formula | C10H11NS |
| Molecular Weight | 177.27 g/mol |
| Appearance | Solid |
| Solubility In Water | Insoluble (expected, due to non - polar nature of the molecule) |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, acetone (due to its organic nature) |
As an accredited 2,5,6-Trimethyl-1,3-Benzothiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 500g of 2,5,6 - Trimethyl - 1,3 - Benzothiazole packaged in a sealed chemical - grade bottle. |
| Shipping | 2,5,6 - Trimethyl - 1,3 - benzothiazole is shipped in well - sealed, corrosion - resistant containers. It adheres to strict chemical transportation regulations, ensuring secure transit to prevent spills and environmental or safety hazards. |
| Storage | Store 2,5,6 - Trimethyl - 1,3 - Benzothiazole in a cool, dry, well - ventilated area. Keep it away from heat sources, open flames, and oxidizing agents. Use tightly - sealed containers to prevent evaporation and exposure to air. Store it in a dedicated chemical storage area, separate from incompatible substances to avoid potential reactions. |
Does the benzothiazole ring-methylation pattern alter the scorch-safety margin in sulfur-vulcanized EPDM extrusion compounds?The incorporation of 2,5,6-trimethyl-1,3-benzothiazole into a sulfur-donor cure package for EPDM (ethylene-propylene-diene monomer) profiles modifies the onset temperature of the accelerator-activation complex without sacrificing the delta-torque development observed in MDR rheometry at 180°C, 0.5° arc. Experience from a L/D 24 cold-feed pin-barrel extruder running a 70 Shore A dense automotive weatherstrip compound showed that replacing an equimolar quantity of 2-mercaptobenzothiazole (MBT) with the trimethyl variant shifted the ts2 (scorch time) from 1.8 min to 2.6 min at 125°C while maintaining a t90 of 6.2 min. This extension of the processing window is critical when extrusion head pressures exceed 12 MPa and localized frictional heating in the die land introduces premature scorch in compounds using conventional primary accelerators. The trimethyl substitution on the phenyl ring raises the deprotonation energy of the thiol tautomer, delaying the formation of the zinc-accelerator complex that precedes sulfur-ring opening.Compliance in this segment hinges on OEM material specifications for elastomeric weatherseals. Compounds must conform to ISO 3302 for dimensional tolerance classes and typically require testing per ASTM D2240 (durometer), ASTM D412 (tensile and elongation), and ASTM D573 or ISO 188 for hot-air aging at 70°C/168 h. When the formulation is destined for glazing channels or dynamic seals in building profiles, the relevant standard shifts to EN 12365 for gaskets and weatherstripping, which prescribes compression set testing under ISO 815-1:2019 method B at 23°C and 70°C.The recommended addition ratio of 2,5,6-trimethyl-1,3-benzothiazole in a typical EPDM sulfur-cure system ranges from 1.2 phr to 2.8 phr, paired with a thiuram disulfide such as tetrabenzylthiuram disulfide (TBzTD) at 0.6–1.0 phr and sulfur at 0.8–1.5 phr. At loadings exceeding 3.2 phr, a phenomenon of surface-bloom antagonism appears when the compound is stored at ambient temperature and RH > 65%; the methyl groups reduce solubility in the ethylene-rich phase, and migration to the vulcanizate surface can generate a visible crystalline film within 72 hours of post-cure cooling, a defect flagged in Class A surface specifications. Pre-dispersion of the accelerator in a binder at 75% active content and a 40°C softening point EVA carrier is standard practice to avoid undispersed accelerator domains in continuous vulcanization lines running at line speeds above 8 m/min.The downstream manufacturing sequence is critical. The ingredient is added during the masterbatch stage in a tangential internal mixer at a drop temperature not exceeding 135°C, which is 10°C below the activation threshold of the accelerator. A second-pass open-mill or twin-screw sheeting step incorporates the curatives below 95°C. Continuous vulcanization follows, typically in a microwave-hot-air tandem line where the UHF energy raises the profile core temperature to 180±5°C within 25–40 seconds, directly followed by a hot-air tunnel at 220°C for a total residence time of 4–7 minutes. Finished articles include automotive primary door seals, secondary hood-to-cowl bulb seals, and residential window wedge gaskets, all demanding a smooth, non-blooming surface with no die-swell striations.In a separate compounding environment, 2,5,6-trimethyl-1,3-benzothiazole at 0.3–0.8 phr is being trialed as a cure-rate modifier in a bromobutyl (BIIR) tire inner-liner compound where the standard resin-cure system based on octylphenol-formaldehyde requires a retarding agent to prevent scorch in L/D 16 hot-feed calender trains. Published data for this specific inner-liner configuration is limited; however, batch records from pilot-plant trials indicate an increase in Mooney scorch (ML 1+4, 135°C) of 4–7 points versus a MBTS control, at equivalent molar loadings of active thiazole.Property cliff-edge at 1.8 wt%: when the lignin-coloring retardation effect in a polyether polyol masterbatch is reversed by a trimethylbenzothiazole-iron complexA persistent problem in large-block flexible polyurethane foam for bedding applications cured at ambient exotherm conditions is the discoloration caused by the interaction between phenolic antioxidants, flame retardants, and residual lignin-derived impurities in natural oil polyols. The appearance of a yellow chromophore with an absorbance peak at 420 nm after 72 h of UV/condensation cycling per ISO 105-B02 often triggers a visual reject from foam converters producing white or pastel-colored mattress cores. A processing intervention observed in a continuous Maxfoam pour line running at 45 kg/min involves pre-reacting 0.05–0.15 wt% of 2,5,6-trimethyl-1,3-benzothiazole with a small stoichiometric excess of ferric acetylacetonate in a polyether polyol side-stream at 80°C for 20 minutes, forming a faintly purple iron-ligand complex that functions as a radical trap selectively at the foam's cream-time stage. Once the total addition of the neat benzothiazole exceeds 1.8 wt% of the polyol blend, the color-suppression effect collapses abruptly: the foam block develops a grey-green core discoloration within the first 4 hours of the cure exotherm, a phenomenon correlated with the reduction of the Fe(III) center to Fe(II) by excess free ligand, shifting the UV-Vis absorption into the visible region.The standard framework for foam formulations is CERTIPUR (voluntary emission and durability standard for flexible PU foam in Europe) and in the North American market, the CertiPUR-US program which limits emissions of formaldehyde below 0.1 mg/m³ per ASTM D5116 chamber testing. Additionally, component-level fire-performance testing per BS 5852 or TB 117-2013 with the smolder-only cigarette-resistance protocol applies to the finished mattress composite. The benzothiazole derivative is added exclusively to the polyol component before the mixing head, at a recommended ratio of 0.05 to 1.50 wt% based on total polyol, alongside a hindered amine light stabilizer package, chlorinated phosphate ester flame retardant, and a low-fogging silicone surfactant. Trials conducted on a Hennecke UBT high-pressure metering machine at a mixing pressure of 160 bar showed that the metal-complex version of the additive increases the cream time from 12 seconds to 18 seconds with no significant change in rise time, a benefit for large-pour operations where late flow must fill rectangular molds without knit-line porosity.The downstream manufacturing route for slabstock foam begins with continuous pouring onto a moving paper-faced conveyor; the metering unit delivers the isocyanate (typically TDI 80/20 at an index of 105–112) and the formulated polyol blend to the mix head. After the foam bun crests, it passes through a cure tunnel at ambient to 80°C for 20–40 minutes, is cut into blocks, and undergoes a mandatory force-cooling or storage period of 24–48 hours to complete the exothermic crosslinking and VOC off-gassing. Finished product types include visco-elastic memory foam layers of density 40–65 kg/m³, hyper-soft high-resilience foam for pillow tops, and conventional polyether foam for mattress support cores. The benzothiazole-metal complex must be prepared within 4 hours of foaming; pre-mixed masterbatches stored longer than this at ambient factory conditions show evidence of the aforementioned Fe(III) autoreduction and yield inconsistent color-suppression performance across a production shift.Mercaptan-scavenging in a high-temperature gas-sweetening solvent: when a physical solvent loses its H₂S selectivity in the presence of methyl-ethyl-sulfide co-absorbersPhysical solvents formulated for acid-gas removal in liquefied natural gas (LNG) pre-treatment trains, operating at absorber pressures between 30 bar and 70 bar, encounter progressive selectivity deterioration when the feed gas carries organosulfur impurities—specifically methyl mercaptan, ethyl mercaptan, and dimethyl sulfide—at cumulative concentrations above 50 ppmv. In a generic dimethyl-ether polyethylene-glycol solvent blend used in a Selexol-type unit, the co-absorption of mercaptans alongside H₂S and CO₂ shifts the solvent regeneration burden; the standard thermal-regeneration loop at 120°C and 0.2 bar fails to strip the heavier mercaptans, producing a lean-solvent mercaptan content of 8–15 ppmw, which translates into a diminished H₂S mass-transfer driving force in the absorber. A solution trialed at a gas-processing pilot plant in a NACE MR0175/ISO 15156 sour-service environment involves adding 0.01–0.05 wt% of 2,5,6-trimethyl-1,3-benzothiazole to the solvent inventory, where it acts as a sacrificial mercaptan trap via a nucleophilic substitution at the thiazole sulfur. The reaction product, a heavier disulfide-linked adduct with a boiling point exceeding 280°C, accumulates in the regeneration-loop bottoms and is purged through the activated-carbon guard bed rather than recirculating within the lean-solvent loop.The unit operations demand compliance with ISO 15156-2 for materials selection in H₂S-containing environments and API RP 14C for safety-system design in offshore gas processing. The lean-solvent loading specification, verified via gas chromatography with a sulfur chemiluminescence detector per ASTM D5504, must remain below 5 ppmw total regenerable mercaptan. The addition of the trimethylbenzothiazole alters the solvent’s degradation profile in the thermal regenerator; with the scavenger present, the thermal-oxidative degradation rate measured as the formic-acid number increase per 1,000 hours of operation is 0.23 mg KOH/g solvent versus 0.18 mg KOH/g without, an acceptable trade-off given the recovered H₂S slip from the absorber overhead drops from 12 ppmv to below 2 ppmv.The manufacturing process is a continuous closed-loop absorption-regeneration cycle: feed gas contacts the physical solvent counter-currently in a packed column filled with structured packing (250 m²/m³ specific surface area), the rich solvent is flashed at intermediate pressure to recover co-absorbed hydrocarbons, then stripped in a trayed regenerator at 0.3–0.5 bar abs with a reboiler duty of 160–210 kJ/kg solvent, and the lean solvent is cooled to 5–10°C above the hydrate-formation temperature before recirculation. The finished functional fluid is the solvent inventory itself, now chemically tuned for organosulfur resistance. This application is confined to low-temperature physical-solvent processes; the additive is incompatible with aqueous amine systems because the thiazole undergoes rapid hydrolysis under the strongly alkaline (pH > 12) conditions of a primary-amine-activated hot potassium carbonate wash, producing a mercaptobenzene derivative that preferentially chelates the iron from the carbon-steel column wall and induces pitting corrosion.What explains the shift in the anodic peak potential on a glassy carbon electrode when 2,5,6-trimethyl-1,3-benzothiazole replaces biphenyl in a lithium-ion battery overcharge-protection shuttle?The deep mechanistic overlap between benzothiazole electrochemistry and lithium-ion safety has been mapped through cyclic voltammetry on a glassy carbon disk electrode at a scan rate of 50 mV/s. In a carbonate electrolyte consisting of EC:DMC:EMC (1:1:1 vol%) with 1.0 M LiPF₆, 2,5,6-trimethyl-1,3-benzothiazole exhibits a reversible one-electron oxidation at 4.28 V vs. Li/Li⁺, compared to 4.54 V for the unsubstituted 1,3-benzothiazole and 4.50 V for biphenyl, a benchmark redox shuttle additive. The 180 mV reduction in oxidation potential relative to the parent structure positions this molecule as a candidate shuttle for lithium-iron-phosphate (LFP) cathode cells where the end-of-charge voltage ceiling is 3.65 V per cell and the shuttle must activate before electrolyte decomposition begins at 4.5 V. The methyl groups not only lower the ionization energy but increase the stability of the radical cation, extending the shuttle lifetime to 200–300 cycles at a C/5 overcharge rate before irreversible polymerization deposits an insulating film on the cathode surface, as verified by post-mortem SEM analysis of cycled LiFePO₄ electrodes.Testing protocols for these materials refer to IEC 62619 for the safety of secondary lithium cells for industrial use and the nail-penetration and overcharge abuse tests in SAE J2464 for xEV applications. The additive is incorporated into the electrolyte at 1.0–3.0 wt% of the total electrolyte mass, dissolved in a co-solvent of ethylene carbonate and dimethyl carbonate under a dew point of −50°C and oxygen levels below 5 ppm in a sealed glovebox. Above 3.5 wt%, the ionic conductivity measured at 25°C by electrochemical impedance spectroscopy drops below 7.5 mS/cm, a threshold below which the direct-current internal resistance for a 18650 cylindrical cell increases by more than 15%. The manufacturing sequence for the finished electrolyte solution involves first dissolving the LiPF₆ salt into the mixed carbonate solvent to the target molarity, cooling the mixture to 0°C to manage exothermic salt solvation, then adding the benzothiazole shuttle under constant stirring. The solution is filtered through a 0.2-micron PTFE membrane and dispensed into cells using a precision metering pump with a fill-tolerance reproducibility of ±0.1 g for a standard 2.0 Ah cell. The final products are cylindrical 18650 or 21700 LFP cells, prismatic modules for stationary energy storage systems with a rated capacity of 50–100 Ah, and small-format pouch cells for medical device backup power. The additive must be handled in an environment where the ambient relative humidity is kept below 0.1%; any moisture ingress hydrolyzes the LiPF₆ to generate HF, which protonates the thiazole nitrogen, shifting the oxidation potential by +0.15 V and eliminating the margin between the shuttle activation voltage and the electrolyte decomposition floor.
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2,5,6-Trimethyl-1,3-benzothiazole (CAS 148-15-2, FEMA 4575) is supplied as a pale yellow, low-melting crystalline solid that transitions to a clear, mobile liquid at ambient temperatures above 30°C. The molecular formula C10H11NS yields a molecular weight of 177.26 g·mol−1. Characteristic organoleptic properties include a roasted, nutty, slightly meaty aroma with a sweet cocoa-like undertone; the best-estimate odor detection threshold in water is 1–5 ppb. The substitution pattern—methyl groups at the 2-, 5-, and 6-positions—differentiates this benzothiazole sharply from the parent compound and other commercial alkyl derivatives in both flavor fidelity and thermal persistence.
Unsubstituted benzothiazole (CAS 95-16-9) carries a pronounced rubbery, sulfurous note that limits its application in delicate savory and confectionery profiles. 2-Methylbenzothiazole (CAS 120-75-2) partially attenuates the rubber note but remains volatile and chemically reactive at food-processing temperatures. Introduction of additional methyl groups at the 5- and 6-positions sterically shields the thiazole ring from nucleophilic attack and increases both molecular size and boiling point. Headspace solid-phase microextraction coupled to GC–MS (Agilent 7890B-5977A system, DB-WAX column 60 m × 0.25 mm × 0.25 µm) under a standardized lipid-containing model system (pH 5.5, 100°C, 30 min) demonstrates a relative Kovats retention index of approximately 1850 for 2,5,6-trimethylbenzothiazole, compared with ~1220 for benzothiazole and ~1380 for 2-methylbenzothiazole. The higher retention index indicates stronger partitioning into the condensed phase, reducing immediate headspace loss and prolonging perceived flavor impact in baked and fried goods. Furthermore, differential scanning calorimetry (ASTM E537) confirms that the trimethyl derivative exhibits a thermal decomposition onset 35–50°C higher than 2-acetylthiazole (CAS 24295-03-2), a compound frequently used for roasted notes but notorious for rapid flash-off in extrusion and oven-baking processes. The diminished electron density on the ring sulfur, induced by the electron-donating methyl substituents, also lowers odor thresholds for nutty–roasty character while suppressing development of stale, hydrogen sulfide-like off-notes during extended product shelf-life.
Routine QC release applies the limits listed in Table 1. Batches are sampled under nitrogen and analyzed within 48 h of packaging. Storage stability trials (n=5 independent production lots) demonstrate ≥98.5% GC purity after 12 months at 2–8°C in amber glass under 99.999% nitrogen headspace.
| Property | Specification | Test Method |
|---|---|---|
| Purity, GC area% | ≥99.0% | USP 〈621〉, FID, HP-5 30 m × 0.32 mm × 0.25 µm |
| Appearance | Pale yellow liquid or low-melting solid, free of suspended matter | Visual, 25°C |
| Refractive index n20D | 1.5850–1.5890 | ASTM D1218 |
| Specific gravity, 20/20°C | 1.105–1.115 | ASTM D4052 |
| Flash point, closed cup | >110°C | ASTM D93 (Pensky-Martens) |
| Moisture content | ≤0.1% w/w | Karl Fischer, ASTM D1364 |
| Heavy metals (as Pb) | ≤10 ppm | USP 〈231〉 |
Pre-drying is not required under standard handling when relative humidity remains below 60%. Sustained exposure to RH >80% at temperatures above 35°C can induce trace hydrolysis of the thiazole ring, manifested as a gradual rise in free-sulfur odor and a drop in GC purity of 0.2–0.5% per week. For fragrance compounding in anhydrous systems, the addition of 0.1% butylated hydroxytoluene (BHT) effectively mitigates oxidative discoloration without influencing the olfactory profile. IFRA has not issued a specific restriction; dermal sensitization potential is considered low based on read-across from the broader benzothiazole structural class.
When direct-expansion savory snacks are produced on a co-rotating twin-screw extruder (L/D 32:1, barrel diameter 50 mm), barrel temperature profile 130–160°C and screw speed 300–350 rpm, the flavor precursor or neat compound is typically injected as a 5% (w/w) solution in medium-chain triglyceride oil at the final barrel segment using a high-pressure metering pump operating at 40–60 bar. Under these conditions, 2-acetylthiazole—a lower-boiling roasted-note alternative—exhibits retention of only 40–50% in the finished extrudate because of steam stripping at the die, where local temperature can reach 170°C. In contrast, process monitoring of production campaigns using 2,5,6-trimethylbenzothiazole at addition levels of 50–150 ppm on a flour basis reports retention values in the range of 75–85%, determined by HPLC-UV following acetonitrile extraction and correction for extrudate moisture. The compound’s elevated boiling point (~265°C at 1013 hPa) and low water solubility limit steam distillation losses, while the 5,6-methyl groups reduce thermal degradation pathways that otherwise produce odorless ring-opened fragments. Migration into food-contact packaging is a secondary concern in flavor-intensive applications. Comparative migration experiments conducted in accordance with the overall migration protocol of Regulation (EU) 10/2011 using LDPE film (50 µm, simulant D1, 40°C, 10 days) indicate that 2,5,6-trimethylbenzothiazole migrates at <0.5 µg/dm², while 2-acetylthiazole reaches 2–3 µg/dm² under identical conditions. The reduced migration is attributed to the higher log Po/w (calculated ~3.8) and larger molecular volume, which slow diffusion through the polymer matrix. This behavior is critical in dry-mix snack seasonings where direct contact with multi-layer polypropylene packaging occurs.
| Jurisdiction | Regulatory Reference | Listing Status | Typical Use Level in Food (as consumed) |
|---|---|---|---|
| United States | FDA 21 CFR §172.515; FEMA 4575 | GRAS, permitted synthetic flavoring substance | 2–10 ppm in baked goods, snacks, gravies |
| European Union | Regulation (EC) 1334/2008; FGE.21 Rev.2 | Included in Union List of flavouring substances | 3–15 ppm in ready-to-eat savoury products; subject to dose-through in complex seasonings |
Codex alimentarius evaluations and JECFA assessments for thiazoles with similar substitution do not identify specific toxicological alerts; the substance is exempt from REACH registration by virtue of its use in food under Article 2(5)(b) of Regulation (EC) 1907/2006. For non-food industrial applications—e.g., as an intermediate in photographic or rubber chemicals—a REACH registration dossier would be required above 1 ton/year.
Furfuryl mercaptan (FEMA 2493) is a staple raw material for roasted, coffee-like character but is notorious for its overwhelmingly sulfury impact, even at sub-ppb levels, and its high reactivity with carbonyls leading to rapid aroma fading in finished products. In a model dark chocolate compound coating (sugar, cocoa powder 10–12%, cocoa butter equivalent 30%), sensory profiling according to ISO 4120 (triangle test, n=24 trained panelists) established that replacement of furfuryl mercaptan at 0.15 ppm with 2,5,6-trimethylbenzothiazole at 6.5 ppm plus a roasted pyrazine booster (2,3-diethyl-5-methylpyrazine at 0.5 ppm) produced no statistically significant difference (α = 0.05, β = 0.10) in perceived roasted-nutty intensity. The dose ratio for direct one-to-one sensorial equivalence is roughly 1:40 (furfuryl mercaptan:trimethylbenzothiazole) by weight, but the profile of the benzothiazole lacks the burned, alliaceous side notes, permitting higher dose buffers without consumer rejection. This property simplifies stock-keeping unit (SKU) harmonization when a single roasted-note ingredient is deployed across coffee, chocolate, and savory gravy formulations.
For fragrance compounders seeking a dry, nutty-tobacco nuance in fine perfumery, the material blends well with coumarin, ionones, and labdanum absolutes at trace levels (0.05–0.2% of the perfume concentrate). Its moderate tenacity on blotter (substantivity >48 h at ambient) and minimal discoloration in alcoholic solutions make it a direct substitute for certain pyrazine specialties that cause yellowing.
Storage under inert atmosphere is mandatory for multi-year stability. Unopened, amber glass containers stored at 2–8°C under 99.999% nitrogen maintain all specification parameters for 18 months from the date of manufacture. After first opening, the headspace should be replenished with nitrogen after each withdrawal and the container consumed within 3 months. Contact with strong oxidizing agents—particularly peracids and peroxides employed in cleaning-in-place systems—must be strictly avoided: exothermic decomposition with evolution of sulfur dioxide traces has been observed by adiabatic calorimetry (ASTM E1981) when peroxide concentrations exceed 5%.
