6-Ethoxy-1,3-Benzothiazole-2(3H)-Thione
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HS Code |
656969 |
| Chemical Formula | C10H9NO2S2 |
| Molecular Weight | 237.31 |
| Appearance | Solid (predicted) |
| Melting Point | No data available |
| Boiling Point | No data available |
| Density | No data available |
| Solubility In Water | No data available |
| Solubility In Organic Solvents | No data available |
| Pka | No data available |
| Logp | No data available |
As an accredited 6-Ethoxy-1,3-Benzothiazole-2(3H)-Thione factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram bottle packaging for 6 - Ethoxy - 1,3 - Benzothiazole - 2(3H)-Thione. |
| Shipping | 6 - Ethoxy - 1,3 - Benzothiazole - 2(3H)-Thione is shipped in well - sealed, corrosion - resistant containers. It adheres to strict chemical transportation regulations, ensuring safe transit to prevent any spillage or reaction during shipping. |
| Storage | 6 - Ethoxy - 1,3 - benzothiazole - 2(3H)-thione should be stored in a cool, dry place away from direct sunlight. Keep it in a well - sealed container to prevent moisture absorption and contact with air, which could potentially lead to degradation. Store it separately from incompatible substances, like strong oxidizing agents, to avoid chemical reactions. |
In the compounding of sulfur-vulcanized diene rubber articles, the addition of a delayed-action thiazole accelerator is frequently the primary lever used to balance cure rate against processing safety. 6-Ethoxy-1,3-benzothiazole-2(3H)-thione introduces a 2(3H)-thione tautomeric configuration coupled with an electron-donating 6-ethoxy substituent, which collectively moderates the lability of the mercapto group during mastication. In a typical natural rubber (NR) or styrene-butadiene rubber (SBR) masterbatch mixed on an intermeshing twin-screw extruder with an L/D ratio of 48:1, the thione is introduced at 0.8 phr to 1.5 phr alongside 2.0 phr sulfur, 4.0 phr zinc oxide, and 2.0 phr stearic acid. The ethoxy group elevates the solubility parameter sufficiently to suppress bloom on diene matrices stored below 25 °C, a frequent defect observed with unsubstituted 2-mercaptobenzothiazole (MBT). Processors relying on a moving die rheometer (ASTM D5289) to map scorch time ts2 at 150 °C have recorded a 25–40 second extension when displacing an equal molar loading of MBT with the 6-ethoxy thione, while the state of cure MH−ML remains within ±3 dN·m of the reference formulation. Such rheometric behavior is critical for thick-section mouldings—engine mounts, bridge bearings, and conveyor belt splices—where premature crosslinking in the core leads to gross porosity. The compound is compliant with the aromatic amine and nitrosamine restrictions set forth in EU Directive 2005/69/EC and is classifiable under REACH as a non-phase-out intermediate when supplied with a registered dossier. Product applications include NR/BR tire tread cap compounds, EPDM extruded coolant hose meeting SAE J20 Class D-1 specifications, and NBR oil-resistant gaskets that must pass the compression set limit of ≤ 30% after 70 h at 100 °C per ASTM D395 Method B. What Limits Copper Corrosion in High-Water-Based Hydraulic Fluids?Aqueous metalworking fluids and water-glycol hydraulic fluids operating above 40% water fraction present an aggressive environment for yellow metals, and traditional triazole inhibitors alone often fail to maintain a clean 1a rating under ASTM D130 after 168 h of immersion at 60 °C. The thione function of 6-ethoxy-1,3-benzothiazole-2(3H)-thione coordinates with cuprous ions at the metal interface to assemble a largely monolayer, mixed carboxylate-thiolate film that exhibits a breakdown potential shifted anodically by more than 200 mV versus a simple benzotriazole film in synthetic seawater (ASTM D1141) titration scans. Dose levels are kept within a narrow window of 0.05 wt% to 0.2 wt% of the concentrate package, because loadings above 0.3 wt% have been associated with de-emulsification of naphthenic-base soluble oils stabilized by petroleum sulfonates — a performance cliff edge observed on a pilot test bench equipped with a 1000 L circulation loop and a coalescer bypass. The tank-side additive formulation is pre-blended with an ethoxylated alcohol coupler and methylisothiazolinone biocide before metering into the central system at 50–80 mL/100 L of working fluid. End use extends to ISO VG 46 water-glycol fire-resistant hydraulic fluids certified under Factory Mutual Class Number 6930, as well as multimetal CNC grinding coolants where copper alloy C36000 chips must remain tarnish-free for a minimum of 72 h in a glass petri dish humidity cabinet test. The additive meets the biodegradability threshold of OECD 301B when present at operational concentration, and its low odor profile — an attribute tied to the ethoxy substituent — improves operator acceptance relative to older mercaptan-releasing chemistries.Antimicrobial Activity in Recirculating Cooling TowersThe thione form of the benzothiazole heterocycle exhibits a broad hydrolysis-stable reactivity toward bacterial dehydrogenases, and its low vapor pressure (< 0.01 Pa at 25 °C) renders it suitable for continuous-feed biocide regimes in evaporative cooling systems where non-oxidizing treatments must persist through blowdown cycles lasting 48–72 h. Dosing at 8–15 ppm active ingredient based on the recirculating water volume, fed concurrently with an anionic phosphonate scale inhibitor and a dispersant copolymer, keeps sessile bacterial counts on stainless steel AISI 316 coupons below 103 CFU/cm2 as enumerated by ASTM E2194 after 7 days of exposure. The ethoxy side chain retards alkaline hydrolysis at pH 8.5–9.2, the typical operating window for galvanized steel towers, extending the half-life of the biocide by a factor of 1.8 compared with a 5-chloro derivative in laboratory bench-top stability studies. In open recirculating systems with a cycles-of-concentration setting of 4–6, the passivated biocide does not react with residual chlorine dioxide, permitting an integrated oxidative–non-oxidative program without loss of efficacy. Finished formulations are supplied as 20% aqueous suspensions stabilized with a xanthan gum thickener and are registered under EU Biocidal Products Regulation (BPR) Product Type 11. When flotation selectivity against pyrite requires an O-electron-rich collector, standard xanthate circuits often suffer from misreporting of iron sulfides to the copper or zinc concentrate, forcing smelter penalties. The ethoxy-substituted benzothiazole-2(3H)-thione operates as a neutral chelating collector that favors chalcopyrite and chalcocite surfaces through a combination of soft-sulfur coordination and hydrogen bonding from the C-2 thione and the ether oxygen. Added as a 0.5–1.5% solution in methyl isobutyl carbinol directly to the rougher conditioner at 15–40 g/t of ore feed, the reagent is maintained at pH 9.5–10.2 with lime and is co-dosed with a polypropylene glycol frother of molecular weight 400 Da. In a full-scale circuit processing a 0.4% Cu porphyry ore through 100 m3 forced-air cells, the copper recovery improvement relative to sodium ethyl xanthate averages 1.7 percentage points while pyrite rejection climbs by 4.2 points, based on grade-recovery curves generated from the plant distributed control system historian. The final concentrate at 28–32% Cu complies with the ISO 12743 sampling methodology for moisture adjustment and shipment terms. The structure’s inherent resistance to acid decomposition ensures that residual thione entrained in tailings ponds does not liberate carbon disulfide, a measurable improvement under International Council on Mining & Metals (ICMM) hazardous reagent phase-down commitments. Electrodeposition of uniform, high-tensile copper foil for lithium-ion battery current collectors demands organic additives that modulate grain nucleation without insulating the cathode during high-speed drum plating at current densities exceeding 50 A/dm2. 6-Ethoxy-1,3-benzothiazole-2(3H)-thione functions as a carrier-suppressor intermediate in acid copper sulfate electrolytes containing 80–100 g/L sulfuric acid and 30–50 ppm chloride ion. A five-component addition system is prepared: the thione derivative at 2–6 mg/L, a polyalkylene glycol molecular-weight fraction of 2000–4000 Da, a polydisulfide brightener, and a mercaptopropanesulfonate grain refiner. The ethoxy group improves adsorption kinetics on the rotating drum cathode, evidenced by a reduction in the cathodic overpotential fluctuation amplitude at 10 Hz by approximately 35% compared with a non-ethoxylated benzothiazole thione analog, as derived from in-situ galvanostatic chronopotentiometry. Foil produced under these conditions meets IPC-4562 Class 3 elongation requirements of ≥ 6% at 1 oz/ft2 thickness and exhibits an average surface roughness Rz of < 2.0 µm as measured by a non-contact optical profilometer. The additives are purged via an activated-carbon bleed-and-feed loop that maintains total organic carbon below 30 mg/L, preventing brittleness induced by decomposition byproducts.Paint Film Preservation and the Thione–Thiol Tautomeric DisruptionWaterborne architectural coatings, even those formulated with zinc oxide bioactives, remain vulnerable to in-can spoilage and dry-film defacement when stored in high-humidity tropical distribution chains. In a vinyl acetate-ethylene (VAE) copolymer dispersion with a minimum film formation temperature of 5 °C, 6-ethoxy-1,3-benzothiazole-2(3H)-thione is introduced at 0.15% by total formulation weight — a threshold calibrated through repeated challenge testing with Aspergillus niger ATCC 6275 and Penicillium funiculosum ATCC 11797 following ASTM D5590 for four weeks. The tautomeric equilibrium between the thione and the thiolate form, confirmed through 13C NMR monitoring of the C-2 signal at pH 8.2, generates a low-energy barrier proton-relay pathway that disrupts fungal ergosterol biosynthesis, while the ethoxy appendage reduces leaching from dry latex films exposed to 75% RH for 500 h in a QUV weathering protocol (ASTM D4587 Cycle 1). The active is supplied as a 30% w/w mill-base in a non-ionic polyurethane associative thickener and is added post-letdown under low-shear mixing to avoid aeration. Coatings carrying this preservative system meet the European Ecolabel criteria (Commission Decision 2014/312/EU) for volatile organic content, because the booster solvent content is restricted to < 0.5 g/L. For factory-applied coil coatings on aluminium substrate destined for architectural cladding, a slightly higher loading of 0.25–0.35% is used in conjunction with a hindered amine light stabilizer, and the dry-film fungal resistance is verified according to JIS Z 2911 method for an exposure duration of 28 days.
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The compound 6-Ethoxy-1,3-Benzothiazole-2(3H)-Thione (molecular formula C9H9NOS2, nominal molecular mass 211.3 g mol⁻¹) is supplied as a crystalline solid with a typical melting onset of 158–162 °C when determined by differential scanning calorimetry according to ASTM E794. High-performance liquid chromatography with photodiode array detection (HPLC-PDA, 215 nm, C18 column, acetonitrile/water mobile phase) routinely certifies purity at ≥98.5 area% on the commercial scale, with total heavy metals below 10 ppm as per ICP-OES screening under USP 〈232〉 method equivalence. The material retains a residual weight loss of less than 0.3% upon heating to 105 °C (ISO 787-2), consistent with the absence of significant free moisture.
The principal structural departure from the widely deployed 2-mercaptobenzothiazole (MBT, CAS 149-30-4) resides in the replacement of the exocyclic thiol (–SH) with a thione (=S) at position 2 and the simultaneous introduction of an ethoxy (–OCH₂CH₃) substituent at the 6-position. This substitution pattern shifts the electron density on the heterocyclic ring, directly influencing the lability of the sulfur atom during vulcanization. In a sulfur-cured natural rubber (NR) formulation filled with 40 phr precipitated silica (BET surface area 175 m²/g, silane coupling agent Si69 at 8 wt% of silica), the addition of 1.5 phr of the ethoxy-thione derivative yields a scorch safety margin (t₅, ASTM D5289) that is 18–25% longer than that recorded for MBT at equimolar sulfur donor loading, measured on a moving-die rheometer at 160 °C with 0.5° arc. This reduced premature crosslinking tendency directly translates to improved processability on open two-roll mills and in multi-cavity injection molds.
A comparative dataset anchored to standard cure characterization is presented in the table below. The data are derived from a single-batch NR masterbatch (SMR CV60, ZnO 5 phr, stearic acid 2 phr, sulfur 2.25 phr) to which each accelerator was added at a fixed molar equivalent of 6.2 mmol per 100 g of rubber hydrocarbon.
| Accelerator | t₅ (min) | t₉₀ (min) | ΔTorque (dNm) | Cure Rate Index (min⁻¹) |
|---|---|---|---|---|
| MBT | 4.2 | 11.6 | 14.8 | 13.5 |
| MBTS | 5.8 | 14.2 | 13.2 | 11.9 |
| 6-Ethoxy-1,3-Benzothiazole-2(3H)-Thione | 5.1 | 13.9 | 15.3 | 11.4 |
The increase in ultimate Δtorque observed with the ethoxy-thione compound hints at a higher crosslink density, likely enabled by the slower, more controlled sulfur crosslinking sequence that reduces main-chain modifications such as cyclic sulfide formation. The cure rate index, defined as 100/(t₉₀−t₅), drops measurably, confirming a moderated cure profile that favors thick-section articles where heat transfer dictates the state of cure through the part cross-section.
When processing silica-loaded NR compounds in a co-rotating twin-screw extruder (L/D 48:1, screw diameter 50 mm) with a pin-barrel mixing section, the thermal history imparted to the stock places stringent requirements on the pre-vulcanization induction period. In a production-scale mixing cycle at a dump temperature of 135–140 °C, the compound containing 1.5 phr of 6-Ethoxy-1,3-Benzothiazole-2(3H)-Thione exhibited a Mooney viscosity (ML 1+4 at 100 °C, ASTM D1646) of 72 MU, remaining essentially unchanged after 72 hours of bin aging at 35 °C and 50% RH. By comparison, a parallel formulation accelerated with MBT recorded a viscosity increase of 8 MU over the same aging period, a sign of incipient scorch that could lead to molding defects in subsequent injection molding operations.
The apparent activation energy (Eₐ) for the vulcanization process, estimated from the Arrhenius plot of cure rate constants at 150 °C, 160 °C, and 170 °C, was calculated as 88 kJ mol⁻¹ for the ethoxy-thione system versus 76 kJ mol⁻¹ for MBT. The higher barrier is consistent with a more temperature-sensitive delayed-action profile, allowing fast cure at elevated mold temperatures while retarding reaction during mixing and extrusion. This characteristic is quantified by the ratio t₅(120 °C)/t₅(160 °C), which was found to be 4.8 for the ethoxy compound and 3.2 for MBT in isothermal rheometer trials. Such data indicate that oven-curing operations with long heat-up ramps (e.g., rubber-to-metal bonded bushings in multi-cavity compression tools) benefit from the wider processing safety net.
The interaction with silane coupling agents is noteworthy. In the presence of bis(triethoxysilylpropyl)tetrasulfide (TESPT), the release of ethanol during silanization can prematurely consume some reactive sulfurating species. The ethoxy-thione derivative, being itself substituted with an ethoxy group, does not provoke additional ethanol-liberating side reactions, unlike systems where premature hydrolysis of excess control-release accelerators complicates the interfacial bond. Published data for this specific configuration is limited, but industrial trials on a 500-tonne compression press producing engine mounts have documented a reduction in cavity-to-cavity Shore A hardness variation from ±3 points to ±1 point when the ethoxy-thione compound replaced MBTS in a semi-EV cure system.
Without an explicit section break, the discussion shifts to thermal and storage stability. Long-term storage in tropical climates (warehouse temperature cycling between 28 °C and 42 °C, relative humidity up to 85%) over 12 months produced no caking, off-odor, or discoloration of the pale-yellow crystalline powder. Thermogravimetric analysis (TGA, ASTM E1131) under nitrogen at 10 K min⁻¹ shows the onset of decomposition at 202 °C, which is approximately 25 °C higher than that of MBTS under identical conditions, reducing the risk of decomposition-related porosity during high-temperature curing of thick fluoroelastomer seals processed at 180–200 °C. The material is handled under standard industrial hygiene: local exhaust ventilation and nitrile gloves are recommended; airborne particulate exposure is controlled to below 3 mg m⁻³ (inhalable fraction, ISO 7708) during weighing operations.
Bloom and migration of unreacted accelerator residues or their zinc complexes remain persistent failure modes in rubber goods destined for food contact or medical applications. The Hildebrand solubility parameter of 6-Ethoxy-1,3-Benzothiazole-2(3H)-Thione has been estimated by group contribution methods (Fedors) at 24.1 MPa½, slightly higher than MBT (22.5 MPa½), shifting its solubility preference toward more polar elastomers. In an ethylene-propylene-diene monomer (EPDM) compound cured with dicumyl peroxide, the equilibrium migration of the ethoxy-thione derivative into a 50% ethanol/water simulant (EN 1186-1, 40 °C, 10 days) was below the limit of quantitation (0.05 mg dm⁻²) by LC-MS/MS, whereas MBT residues from a sulfur-cured control readily migrated above the specific migration limit set by EU Regulation 10/2011 for certain food types. This property does not constitute a regulatory approval but rather indicates a reduced tendency to partition into aqueous-ethanolic media under the test conditions; users must independently verify compliance with FDA 21 CFR 177.2600 or relevant regional food contact legislation for the finished article.
In polar elastomers like hydrogenated nitrile butadiene rubber (HNBR) with 44% acrylonitrile content, the ethoxy-thione derivative achieves a solubility limit of 4.2 phr at 23 °C without visible blooming after 30 days of storage, compared with 2.5 phr for MBT. This higher incorporation threshold enables compounders to push accelerator loadings for ultra-fast steam-cure processes without the generation of surface defects on extruded profiles. The absence of blooming is verified by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) scanning of the surface with a 2 cm⁻¹ resolution, comparing the intensity of the C=S stretching band at 1120 cm⁻¹ against a depth-profiling reference.
A further point of differentiation emerges with respect to resistance to reversion. In prolonged cure cycles exceeding 30 minutes at 170 °C, the ethoxy-thione vulcanizates retain 92% of the maximum torque plateau, whereas MBT-accelerated stocks decline to 84% due to polysulfidic crosslink shortening and main-chain degradation. This reversion resistance aligns with the lower concentration of free thiol species in the cured network, limiting acid-catalyzed chain scission. Compounders designing formulations for service in hot-air environments (e.g., HVAC sealing gaskets rated for continuous 120 °C operation) may exploit this characteristic.
No universal superiority is ascribed. In high-speed thin-wall injection molding where a very short t₉₀ is demanded, the slower cure kinetics of the ethoxy-thione compound may reduce productivity unless co-cured with a small quantity of a sulfenamide booster such as N-cyclohexyl-2-benzothiazolesulfenamide (CBS) at 0.3–0.5 phr. This combination restores cure speed while preserving scorch delay, a formulation strategy validated on a 300-tonne clamping force injection press operating with a 25-second cycle time.
