Thiazoles
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HS Code |
269441 |
| Chemical Class | Heterocyclic organic compounds |
| Ring Structure | Five - membered ring with one sulfur and one nitrogen atom |
| Odor | Often have a pungent or unpleasant odor |
| Solubility | Moderately soluble in organic solvents like ethanol, less soluble in water |
| Melting Point | Varies widely depending on the substitution, can range from low - melting solids to high - melting solids |
| Boiling Point | Typically higher than many simple hydrocarbons due to polar nature |
| Stability | Fairly stable under normal conditions but can react under specific chemical environments |
| Reactivity | Can participate in various reactions such as nucleophilic substitution, electrophilic aromatic substitution |
| Color | Generally colorless to pale - colored solids or liquids |
| Pharmaceutical Activity | Some thiazoles have antibacterial, antifungal, and anti - inflammatory properties |
As an accredited Thiazoles factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Thiazoles in sealed containers, 500g per package for secure storage and handling. |
| Shipping | Thiazoles, being chemicals, require careful shipping. They are typically packaged in sealed, corrosion - resistant containers. Shipment must comply with hazardous material regulations, ensuring proper handling and transportation to prevent spills and environmental risks. |
| Storage | Thiazoles should be stored in a cool, dry, well - ventilated area, away from heat sources and open flames. They should be separated from oxidizing agents, strong acids, and bases to prevent chemical reactions. Store them in tightly sealed containers to avoid exposure to air and moisture, which could potentially degrade the compound or cause unwanted reactions. |
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Thiazole-based chemical intermediates occupy irreversible positions in crosslinking kinetics, metal surface passivation, fungal cell division inhibition, and β-lactam antibiotic synthesis. The application-specific evaluations below provide formulation ranges anchored to validated test protocols and production-scale equipment parameters, with all claims containing a direct link to an ASTM, ISO, DIN, or FDA 21 CFR designation.
How Does Accelerator Flocculation Impact Truck Tyre Tread Selenium-Donor Synergy?In long-haul truck tyre tread compounds based on NR/BR blends, the sulfur crosslinking density and reversion resistance critically depend on the solubility limit of 2-mercaptobenzothiazole disulfide (MBTS) in the rubber matrix. When MBTS loading exceeds 1.8 phr in a compound containing 40 phr N330 carbon black, surface bloom and micro-flocculation nucleate at the filler-polymer interface, causing a measurable drop in strain-crystallisation reinforcement measured by low-field time-domain NMR (residual dipolar coupling constant shift exceeding 15%). Under production conditions on a tandem mixing line comprising a 270-litre tangential-rotor internal mixer (Banbury F270, fill factor 0.75) followed by a twin-screw dump extruder with L/D 14:1, the masterbatch containing MBTS and a sulphenamide primary accelerator must maintain stock temperature below 155 °C during the second pass to prevent premature dissociation of the sulphenamide group. The hot-feed pin-barrel cold-feed extruder in the tyre building hall then processes the compound at a screw speed limited to 32 rpm to keep head pressure below 18 MPa, directly influencing tread dimensional stability around the breaker. Accelerator combinations that embed selenium diethyldithiocarbamate at 0.15–0.25 phr together with N-tert-butyl-2-benzothiazole sulphenamide (TBBS) at 0.9–1.1 phr yield a plateau modulus retention of 87% after 90 min at 160 °C when tested per ASTM D5289, compared to 62% for binary MBT/TBBS formulations without selenium donor. Compliance with the German TRGS 552 and the analytical method EN 12868 requires that volatile N-nitrosamines released during vulcanisation remain below 0.5 μg/m³, a boundary that forces the substitution of free MBT with coated MBTS grades having a mean particle diameter D50 ≤ 12 µm. Finished goods include 315/80R22.5 all-position truck tyres, elastomeric marine fender profiles, and steel cord conveyor belts operating at continuous temperatures up to 110 °C. Benzothiazole Mercaptide Formation in Hard Water and Spray Tool CorrosionSodium 2-mercaptobenzothiazole (NaMBT), supplied as a 50% aqueous solution, functions as a mixed-type corrosion inhibitor for yellow metals and galvanised steel in semi-synthetic metalworking fluids diluted to 5–8% in make-up water. At a sump concentration of 0.12–0.25 wt% active NaMBT relative to the diluted emulsion, the inhibitor forms a chemisorbed mercaptide film on copper and zinc surfaces detectable by X-ray photoelectron spectroscopy through the S 2p3/2 peak at 162.5 eV. In central coolant systems serving a transfer line machining ductile iron cylinder blocks, the free calcium ion concentration originating from water hardness above 380 mg/L CaCO₃ precipitates calcium benzothiazole mercaptide as a sticky pale-yellow sludge, which clogs 80-mesh pleated bag filters within 72 hours of recirculation. Mitigation relies on pre-chelating the concentrate with ethylenediaminetetraacetic acid tetrasodium salt at a molar ratio of 1:1.05 (EDTA:Ca), a step verified by EDTA titration per DIN 38406-3. The machined component—an ISO-K 250 flange–undergoes an in-process leak test before assembly; pitting depth measured by white-light interferometry must stay below 3 µm, confirming that the inhibited fluid maintains a chip-test mass loss below 1.8 mg/cm² when tested with degreased cast iron chips per ASTM D4627. Copper coupon tarnish classification remains ≤ 1b under ASTM D130 at 60 °C for 48 hours. The end-use dilution feeds a Grob BZ510 six-spindle machining centre performing drilling, threading, and gun-reaming operations on C45 steel, with sump life extended to 18 months without biocide intervention. Achieving a 1:1 selectivity ratio between copper and tantalum nitride in barrier chemical mechanical planarisation at 300 mm wafer scale requires a heterocyclic azole that suppresses static etch yet desorbs rapidly under shear. 2-Mercaptobenzothiazole delivered at 0.008–0.015 wt% relative to the total slurry mass, in a colloidal silica-based alkaline slurry (fumed silica 12 wt%, pH 9.8–10.2 adjusted with KOH, containing 2.5% H₂O₂ as the oxidiser and 0.05% benzotriazole as a co-inhibitor), provides a copper static etch rate of 3.8 Å/min measured by four-point probe sheet-resistance mapping while maintaining a bulk removal rate of 6200 Å/min on an Applied Materials Reflexion LK polisher equipped with an IC1010 grooved pad at 1.5 psi downforce and 93 rpm platen speed. The slurry is filtered through a 0.5 µm depth filter immediately prior to the point-of-use dispense to remove MBT re-crystallisation nuclei that form during a 72-hour batch aging period. Post-CMP cleaning employs a dilute tetramethylammonium hydroxide rinse at 0.15% to lift residual MBT without attacking the low-k dielectric, as verified by TXRF surface metal contamination below 1×10¹⁰ atoms/cm². Compliance with SEMI F104 test method for slurry chemical characteristics and with the EU RoHS directive regarding homogeneous material restrictions is mandatory for the logic device manufacturer; the finished wafers containing dual-damascene copper interconnects proceed to probing on a 28 nm low-power mobile SoC process. When 2-(Thiazol-4-yl)benzimidazole Replaces Carbendazim in Low-VOC Architectural Coatings2-(Thiazol-4-yl)benzimidazole (thiabendazole, TBZ), introduced as a dry-film fungicide in styrene-acrylic interior wall paints formulated below 30 g/L VOC according to Directive 2004/42/EC, requires a pre-dispersion step in a horizontal bead mill charged with 0.8–1.2 mm yttria-stabilised zirconia beads to reduce the median particle size of the crystalline TBZ from its supplied D50 of 45 µm to a final grind of D90 < 10 µm. Failing to achieve this fineness results in visible specking on a smooth roller-applied finish and a drop in fungal resistance because the effective surface area of the biocide is insufficient. The pigment volume concentration of the coating, typically held at 42–48%, modulates the leach rate of TBZ: at a film loading of 0.45–0.75% TBZ on dry coating weight, a constant-rate diffusion of 2.5–4.0 µg/cm²/month in distilled water is measured by HPLC-UV at 302 nm, fulfilling the fungal resistance criteria of EN 15458:2022 method A after 2000 hours of QUV-A accelerated weathering. However, TBZ suffers a photodegradation quantum yield of 0.18 in a UVA-rich environment, causing yellowing (Δb* ≥ 4.2) of the white topcoat unless a hindered amine light stabiliser is co-added at a ratio of 0.3% on binder solids. The compliance dossier for a Biocidal Product Regulation (BPR) authorisation under EU 528/2012 product-type 7 must include a storage stability test at 54 °C for 14 days proving that the TBZ assay does not fall below 95% of its initial value. End-use products include hospital corridor matte emulsion paints, anti-mould acrylic sealants for wet-room joints, and pre-pasted wallpaper adhesives protected against Aspergillus niger and Penicillium funiculosum. Synthesis of 2-chloro-5-chloromethylthiazole via continuous vapor-phase chlorination of 2-chloro-5-methylthiazole over a γ-alumina catalyst bed packed into a Hastelloy C-276 tubular reactor with an internal diameter of 38 mm and a heated length of 2.4 m provides the critical side-chain intermediate for the neonicotinoid insecticide thiamethoxam. The feed stream, consisting of 2-chloro-5-methylthiazole vapour and chlorine gas in a molar ratio of 1:1.08, preheated to 195 °C, enters the reactor at a weight hourly space velocity of 0.85 h⁻¹. The exotherm is controlled by a molten salt jacket maintaining the tube skin at 218 ± 3 °C; exceeding 225 °C generates over-chlorinated side products including 2-chloro-4,5-bis(chloromethyl)thiazole, which reaches a concentration of 0.8 area% by GC and must be separated through a packed distillation column operating at a reflux ratio of 6:1 and a bottom temperature of 167 °C under 95 mbar vacuum. The purified bottom stream yields 99.2% assay 2-chloro-5-chloromethylthiazole with a crystallisation point of 31.2 °C, which is directly transferred to a jacketed stainless-steel holding tank at 45 °C to prevent solidification. In the downstream condensation with 3-methyl-4-nitroimino-tetrahydro-1,3,5-oxadiazine, the required stoichiometric excess of the thiazole intermediate is 3 mol% to drive conversion above 98%. Formulators using thiamethoxam technical-grade (≥ 97% assay, CIPAC MT 710) produce water-dispersible granules for seed treatment and foliar spray; the active substance authorisation according to EC 1107/2009 requires the technical concentrate to contain less than 0.1 mg/kg N-nitroso-thiamethoxam as a relevant impurity. Synthetic Cephalosporin Precursors Demand Residual Water Below 0.15%The coupling of 2-(2-aminothiazol-4-yl)-2-methoxyiminoacetic acid (ATMA), activated as its benzothiazolyl thioester, with 7-aminocephalosporanic acid (7-ACA) in the production of cefotaxime sodium is carried out in a glass-lined 5000-litre reactor at ‑15 ± 2 °C under a nitrogen blanket. The ATMA thioester, synthesised immediately before use by reacting the free acid with 2,2′-dibenzothiazyl disulfide and triphenylphosphine in dichloromethane, must exhibit a residual moisture content below 0.10% by Karl Fischer coulometry (Metrohm 831 KF Coulometer) to prevent hydrolysis of the activated ester, which would lower the yield of the acylation to below 82%. During the 3.5-hour acylation, the pH of the aqueous phase containing dissolved 7-ACA is maintained at 7.8–8.2 by automated addition of 20% triethylamine solution, while the consumption of the thioester is monitored by in-situ ReactIR, tracking the disappearance of the thioester carbonyl stretch at 1694 cm⁻¹. After phase separation and solvent switching to aqueous acetone, the cefotaxime acid is precipitated at its isoelectric point (pH 3.2), filtered through a 0.45-µm membrane, and converted to the sterile sodium salt. The final API monograph per USP 43 and Ph. Eur. 10.3 stipulates that the sum of any individual impurity detected by HPLC at 254 nm must not exceed 0.10 area% for known related substances, with the critical dimer impurity controlled below 0.05 area%. Compliance with ICH Q7 for the intermediate stage mandates full traceability of raw materials and an audit trail of reaction parameters; the intermediate holding time between the thioester formation and the acylation step is limited to 90 minutes at 0–5 °C to stay below the detectable degradation threshold. Production-scale batches with a final cefotaxime sodium potency of 968 µg/mg (anhydrous) are filled under aseptic conditions into Type II glass vials for injectable suspension, used in empiric therapy of community-acquired pneumonia.
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As a structural class, thiazoles encompass the parent 1,3-thiazole ring system and its benzo-fused analogs (benzothiazoles), along with a broad array of substituted derivatives that function as vulcanization accelerators, corrosion inhibitors, pharmaceutical building blocks, and agrochemical intermediates. The core five-membered heterocycle, containing sulfur at the 1-position and nitrogen at the 3-position, exhibits a dipole moment of approximately 1.6 D and a pKa near 2.5 for the conjugate acid, imparting sufficient electron deficiency to participate in nucleophilic aromatic substitution yet enough stability to withstand processing temperatures exceeding 170 °C when substituted with electron-withdrawing groups. Commercially, thiazoles are differentiated from oxazoles primarily by the exchange of oxygen for sulfur, which lowers ring aromaticity slightly (resonance energy roughly 100 kJ/mol versus 105 kJ/mol for oxazole) and significantly alters metal-binding behavior and thermal decomposition pathways in polymer matrices.
In high-speed rubber compounding on tangential and intermeshing twin-screw extruders with L/D ratios between 32:1 and 48:1, the selection of thiazole accelerator chemistry directly dictates the processing window. 2-Mercaptobenzothiazole (MBT, CAS 149-30-4) delivers a rapid cure onset but carries a Mooney scorch time (MS at 121 °C, per ASTM D1646) of less than 10 min in natural rubber formulations loaded with 50 phr N330 carbon black. This narrow window often results in premature crosslinking in dead spots along the barrel wall when melt temperatures exceed 135 °C. For injection molding with clamp forces above 200 metric tons, processors frequently shift to 2,2’-dibenzothiazyl disulfide (MBTS, melting point range 177–181 °C), which extends scorch time to approximately 20 min under the same Mooney conditions while delivering a torque increase (MH–ML) in the moving die rheometer (MDR, ASTM D5289) of 18–22 dNm at 160 °C. The disulfide bridge in MBTS functions as a latency mechanism: thermal cleavage above 140 °C liberates reactive MBT radicals, effectively decoupling stock viscosity from cure state during the filling phase. N-cyclohexyl-2-benzothiazole sulfenamide (CBS), with a melting onset near 97 °C, further extends the scorch margin to beyond 30 min and is preferred for tire body ply compounds where the reversion resistance index (RRI, calculated as MH at 190 °C divided by MH at 160 °C) must remain above 0.80. All three accelerators evolve nitrogen-containing heterocyclic residues during vulcanization; in compounds containing secondary amine antiozonants such as N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD), measurable N-nitrosamine levels can appear, requiring a cap on amine additive loading below 0.5 phr to maintain workplace air concentrations under the 0.5 µg/m³ action limit referenced in German TRGS 552.
Where thiazole accelerators intersect with zinc oxide (4–6 phr) and stearic acid (2 phr), a zinc-thiolate complex forms in situ, and the optimal stoichiometry corresponds to a molar ratio of ZnO to MBT near 1.1:1.0. Below this, residual sulfur bloom occurs on the surface of cured slabs stored at 40 °C and 70% relative humidity within 72 hours. Above a ZnO loading of 8 phr, the onset of zinc stearate crystallization can raise compound viscosity by 5–7 Mooney units and reduce die swell, which complicates profile extrusion of EPDM seals to tolerances tighter than ±0.15 mm. This stands in contrast to thiuram disulfide ultra-accelerators, which do not require zinc activation and thus sidestep metal-soap rheology effects but exhibit scorch times often under 5 min and generate higher concentrations of carbon disulfide during cure.
What Limits Mercaptobenzothiazole’s Performance in High-Temperature Sour Gas Environments?
Benzothiazole-based film-forming corrosion inhibitors for mild steel in oilfield produced water rely on the thione-thiol tautomerism of MBT-like compounds to chemisorb onto iron surfaces. In NACE TM0172 test brines containing 5 wt% NaCl and saturated CO2 at 80 °C, 2-(dibutylamino)methylbenzothiazole at 50 ppm by volume yields an inhibitor efficiency above 92% as measured by linear polarization resistance (LPR). However, when H2S partial pressure exceeds 0.3 bar at temperatures above 120 °C, the protective iron-thiazole film converts to non-protective iron sulfide scales, leading to a drop in polarization resistance below 100 Ω·cm². In such sour systems, imidazoline-based inhibitors frequently outperform thiazoles because the imidazoline ring exhibits greater hydrolytic stability in the presence of bisulfide ions. Published data for this specific H2S threshold in deep gas wells is limited, though field trials on a 16-inch carbon steel flowline in the Permian Basin indicated that a blended benzothiazole-quaternary ammonium inhibitor maintained a corrosion rate below 0.1 mm/year up to 0.25 bar H2S before efficiency degraded.
The 2-aminothiazole scaffold appears in over 18 FDA-approved small-molecule drugs, functioning as a non-classical bioisostere for the amide bond and for the phenol ring in tyrosine kinase inhibitors. In the solid-state synthesis of dasatinib monohydrate, the coupling of a 2-amino-N-(2-chloro-6-methylphenyl)-5-thiazolecarboxamide fragment is carried out under anhydrous tetrahydrofuran at −20 °C to prevent hydrolysis of the acid chloride intermediate. The difference between thiazole and oxazole in this context is pharmacokinetic: the sulfur atom increases lipophilicity (ClogP increment roughly +0.4 units) and reduces the compound’s susceptibility to cytochrome P450-mediated ring oxidation, thereby extending plasma half-life by approximately 2–3 hours in rodent models. A specification for a typical pharmaceutical-grade 4-(4-methylpiperazin-1-yl)-1,3-thiazole-2-amine intermediate would require HPLC purity greater than 99.5 area%, residual solvents below ICH Q3C limits, and heavy metals below 10 ppm by USP <231> Method II.
| Accelerator | Melt Point (°C) | Scorch Time MS t5 at 121°C (min) | Optimum Cure Time t90 at 160°C (min) | MH (dNm) | |
|---|---|---|---|---|---|
| MBT | 178–182 | 8 | 12 | 24 | |
| MBTS | 177–181 | 22 | 18 | 20 | |
| CBS | 97–101 | 35 | 22 | 19 | |
| ZMBT (Zinc salt of MBT) | decomp. >300 | 14 | 15 | 22 |
Formulation: SBR 1502 70 phr, BR 1203 30 phr, N330 carbon black 50 phr, ZnO 5 phr, stearic acid 2 phr, sulfur 2 phr, accelerator 1.2 phr. Data obtained on a MDR at 160°C, arc 0.5°, per ASTM D5289-19. Reprinted values are typical of industrial mixing campaigns on a 1.6 L Banbury internal mixer with a drop temperature of 150°C.
When liquid thiazole-based fungicides such as 2-(4-thiazolyl)benzimidazole (thiabendazole, TBZ) are applied as post-harvest dips for citrus, the operational boundary narrows sharply. The suspension concentrate must maintain viscosity below 500 mPa·s at 25°C to pass through air-induction nozzles at 3 bar, yet the active ingredient has a solubility of only 30 mg/L in water at neutral pH. This dictates a particle size distribution with D90 below 4 µm, achieved via bead milling with 0.6–0.8 mm yttria-stabilized zirconia media. Differences from triazole fungicides like tebuconazole become evident under alkaline hydrolytic stress: TBZ exhibits less than 5% degradation after 14 days at pH 9.5 and 40°C, whereas triazole rings undergo ring-opening at the C−N bond, forming inactive triazolyl-acetamide byproducts. FDA tolerances under 21 CFR 556.730 specify a residue limit of 10 ppm in edible tissues of cattle, a figure that dictates pre-slaughter withdrawal intervals tracked via ELISA screening with a limit of detection of 2 ppb.
| Compound | Standard | Specification Parameter | Limit |
|---|---|---|---|
| MBT | ISO 102:2019 (Rubber compounding ingredients) | Ash content | ≤ 0.5% |
| MBTS | ASTM D4817-20 | Purity by TGA | ≥ 95% active |
| CBS | FDA 21 CFR 177.2600 | Migration limit for rubber articles in dry food contact | ≤ 0.5 mg/in² total extractives |
| Thiabendazole | FAO/WHO JMPR (2019) | ADI (acceptable daily intake) | 0–0.1 mg/kg bw |
| Benzothiazole (general) | REACH Annex XVII entry 72 | PAH content restriction in extender oils | BaP < 1 mg/kg |
In the compounding of rubber-to-metal bonded mounts for automotive vibration damping, a pre-dried silica-filled NR formulation containing CBS at 1.5 phr requires a conditioning period of 24 hours at 23°C and 50% relative humidity after mixing before bonding to phosphated steel with an aqueous epoxy-silane adhesive. Failure to condition results in adhesive blistering during cure at 160°C, attributed to residual moisture combining with amine decomposition products from the sulfenamide. The blister threshold, determined via bonded T-peel testing per ASTM D429 Method B, corresponds to a compound moisture content above 0.25 wt% as measured by Karl Fischer titration on a molded slug.
