5-Methyl-1,2,4-Triazolo[3,4-B][1,3]Benzothiazole
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HS Code |
968498 |
| Chemical Formula | C9H7N5S |
| Molecular Weight | 217.25 g/mol |
| Appearance | Solid (usually a powder or crystalline solid) |
| Melting Point | Varies, typically in a specific temperature range |
| Solubility | Solubility in common solvents like water, ethanol, etc. varies |
| Density | Specific density value (g/cm³) depending on conditions |
| Pka | Acid dissociation constant value relevant to its acidic or basic nature |
| Uv Vis Absorption | Characteristic absorption wavelengths in UV - Vis spectrum |
| Ir Absorption | Characteristic absorption bands in infrared spectrum |
As an accredited 5-Methyl-1,2,4-Triazolo[3,4-B][1,3]Benzothiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of 5 - Methyl - 1,2,4 - Triazolo[3,4 - B][1,3]Benzothiazole in sealed chemical - grade packaging. |
| Shipping | 5 - Methyl - 1,2,4 - Triazolo[3,4 - B][1,3]Benzothiazole is shipped in properly sealed containers, compliant with chemical transport regulations. Shipment ensures protection from environmental factors and secure handling during transit. |
| Storage | 5 - Methyl - 1,2,4 - Triazolo[3,4 - B][1,3]Benzothiazole should be stored in a cool, dry, well - ventilated area. Keep it away from heat sources, open flames, and oxidizing agents. Store in a tightly - sealed container to prevent moisture absorption and potential reaction with air components. Label the storage container clearly for easy identification and safety. |
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The diazonium salt derived from 5-methyl-1,2,4-triazolo[3,4-b]benzothiazole undergoes coupling with N,N-diethylaniline in a jacketed glass-lined reactor to generate a heterocyclic monoazo chromophore that exhaust dyes polyacrylonitrile fibers to deep scarlet shades at 0.5% o.w.f. The electron‑withdrawing thiazole ring and methyl‑substituted triazole moiety produce a bathochromic shift relative to benzothiazole‑based dyes, yielding λmax near 530 nm and a molar extinction coefficient sufficiently high to allow reduced dyestuff inventory. Every batch intended for textile mills operating under ZDHC MRSL V3.0 must be verified via HPLC‑UV to confirm that free aromatic amine content remains below 30 mg/kg, in alignment with OEKO‑TEX Standard 100 Annex 4. The synthetic sequence on a 3,000 L scale proceeds by charging the amine intermediate into 85% phosphoric acid, cooling to –5 °C, and feeding sodium nitrite solution over 45 min while maintaining a molar ratio of NaNO2 to amine of 1.02:1. After diazotization, the clear solution is transferred to a coupling vessel containing the tertiary aromatic amine pre‑dissolved in dilute hydrochloric acid, where the instantaneous coupling at 0–2 °C yields the water‑soluble cationic dye. Salting‑out with 15% w/v sodium chloride followed by plate‑and‑frame filtration generates a press cake that is dried in a fluidized‑bed dryer with inlet air at 110 °C to a moisture content below 2%. The resulting powdered product is standardised with dextrin to 250% relative tintorial strength. End‑product forms include low‑dust granules for automatic metering and liquid brands supplied in IBC totes for continuous dyeing ranges; the mill‑applied commodity is typically labelled as a derivative of C.I. Basic Red. Cure‑Retarder Chemistry in Peroxide‑Cured EPDM ExtrusionsWhen EPDM compounds are crosslinked with dicumyl peroxide at 175 °C, the scorch safety margin often collapses below 30 s on a twin‑roll mill, leaving narrow processing windows for complex profiles. 5‑Methyl‑1,2,4‑triazolo[3,4‑b]benzothiazole functions as a reversible radical‑trap retarder that does not decompose into secondary amines capable of generating N‑nitrosamines, a property critical for compliance with EU REACH Annex XVII entry 43 and the German TRGS 552 directive. The recommended loading spans 0.5–2.0 phr, scaled within that range according to filler loading: carbon‑black‑filled compounds at 80 phr N550 typically require 1.2–1.8 phr, while mineral‑filled insulation grades operate effectively at 0.8 phr. Mixing is carried out in an intermeshing tangential internal mixer (Banbury BR1600, net chamber volume 120 L) with a fill factor of 0.72 and a ram pressure of 5.5 bar. The retarder is pre‑dispersed on a hydrocarbon wax binder and added together with ZnO and stearic acid in the first pass, where the dump temperature is capped at 125 °C to prevent premature crosslinking. After a second pass on a two‑roll sheeting mill set to 45 °C, the stock is extruded through a 90 mm cold‑feed extruder (L/D 20:1) equipped with a gear pump to a profile die, and continuously vulcanized in a hot‑air tunnel at 230 °C for 4 min. End‑articles include drinking‑water sealing gaskets formulated under the plasticiser migration limits of (EU) No. 10/2011 when the compound is tested with simulant D at 40 °C for 10 days, and automotive coolant hoses that must withstand 3,000 h of static soak at 125 °C without cracking. The retarder does not interfere with the peroxide crosslink density; MDR rheometry at 180 °C consistently shows a final torque (MH) retention above 97% of the un‑retarded control, while Ts2 elongation of 80–130% widens the fabrication window sufficiently to run multi‑cavity injection moulds with clamp forces exceeding 400 t. In one‑component moisture‑cure polyurethane hot‑melt adhesives based on 4,4′‑MDI and a linear polyether polyol, the pre‑polymer often undergoes unintended viscosity drift during 6–12 month warehouse storage at 25 °C, driven by residual tin catalyst activity. Blending 0.03 wt% of 5‑methyl‑1,2,4‑triazolo[3,4‑b]benzothiazole into the finished pre‑polymer under dry nitrogen creates a transient ligand that reversibly coordinates dibutyltin dilaurate. The immediate effect is an extension of pot life at 50 °C from 45 min to beyond 90 min, measured by parallel‑plate oscillatory rheometry at 1 Hz. The equilibrium constant of the coordination complex is temperature‑sensitive; upon application at 80 °C bead temperature, the de‑protection releases the active catalyst, allowing full through‑cure of a 6 mm bead to reach 80% of ultimate tensile strength within 24 h under 50%RH, as verified on tensile specimens punched according to ISO 37 type 2. The final cured sealant retains 98% of the control formulation’s elongation at break. Manufacturing integration occurs inside a planetary mixer with vacuum capability (–0.095 MPa) at a jacket temperature of 70 °C; the inhibitor is dosed as a 10% solution in dioctyl adipate after the degassing step. An inline 200 µm wire‑mesh filter removes any undissolved particulates prior to 310 mL aluminium cartridge filling. The terminal products are single‑component sealants qualified under ISO 11600 and ASTM C920, deployed in automotive windshield bonding lines where deep‑cure after 7 days must exceed 3.5 MPa lap‑shear strength on primed glass, and in commercial glazing where the seal must pass ASTM E2190 argon permeation limits. Why Gas‑Turbine Lubricant Formulations Demand Metal Deactivators Beyond BenzotriazoleOperational sump temperatures in advanced aeroderivative gas turbines routinely exceed 160 °C, at which point conventional benzotriazole derivatives volatilise or deposit lacquer on steel‑alloy surfaces. 5‑Methyl‑1,2,4‑triazolo[3,4‑b]benzothiazole, with a 1,2,4‑triazolo ring fused to a benzothiazole backbone, shows a thermal decomposition onset (TGA, 10 °C/min, nitrogen) approximately 55 °C higher than that of tolyltriazole, a behaviour attributed to the extended aromaticity that stabilises the chelate formed with cuprous ions. When compounded into a PAO‑based ISO VG 46 turbine oil at 0.05% active substance, the additive passes the 1,200 min oxidative induction time benchmark of ASTM D6186 (160 °C, O2 at 3.4 MPa) while keeping pentane‑insoluble sludge below 0.3%. Adherence to MIL‑PRF‑23699F (thermal stability and corrosiveness test at 274 °C for 96 h) and ASTM D4378 condition‑based routine chemical monitoring enables inclusion in approval dossiers for both aeronautical and stationary turbine fluids. Formulation blending proceeds in a 5,000 L heated stainless‑steel vessel equipped with a high‑shear disperser; the heterocyclic powder is first wetted with a 5 cSt alkylated naphthalene co‑solvent at 80 °C and stirred for 40 min until complete dissolution before transferring to the base oil charge. Downstream end‑fluids include ISO‑LH‑CKB turbine oils and VLCC stern‑tube lubricants where copper alloy bearings require year‑long passive corrosion protection. The component also reduces acid number build‑up in ester‑based generation‑2 high‑temperature fluids, though compatiblity with overbased calcium sulfonate detergent packages must be verified by a modified ASTM D2896 base number retention study; published data for this specific combination remains limited.
Where cereal seed‑borne pathogens such as Ustilago nuda and Tilletia caries demand a systemically mobile succinate dehydrogenase inhibitor (SDHI) with extremely low aqueous solubility to minimise leaching from the dressing zone, the 5‑methyl‑1,2,4‑triazolo[3,4‑b]benzothiazole scaffold has been employed as the heterocyclic amine coupling partner in the synthesis of the amide‑linked active ingredient. The condensation is conducted under the requirements of EU Plant Protection Products Regulation (EC) No. 1107/2009, and the technical material must conform to FAO Specification 825/TC for triazolothiazole‑based SDHIs with a minimum purity of 965 g/kg. In the manufacturing campaign, 120 kg of the amine (dry basis, purity >99%) is suspended in 800 L of acetonitrile, and 1.1 molar equivalents of 3‑difluoromethyl‑1‑methyl‑1H‑pyrazole‑4‑carbonyl chloride are added dropwise over 3 h at 38–42 °C in the presence of 1.3 molar equivalents of triethylamine. After aqueous work‑up and phase separation, the organic layer is subjected to wiped‑film evaporation at 70 °C / 10 mbar to recover the solvent, and the wet solid is dried in a conical vacuum dryer (jacket temperature 55 °C, 5 mbar) until the loss on drying is below 0.5%. The resulting technical‑grade powder is then micronised to a median particle size d50 of 1.8 µm and formulated as a 250 g/L flowable seed treatment suspension containing a 3% polyvinyl alcohol binder and a 0.2% polysiloxane antifoam. The finished agrochemical is packaged in 20 L fluorinated HDPE drums and applied via continuous‑throughput seed treaters at a rate of 100 mL/100 kg wheat seed to deliver 25 g a.i./dt. The supply chain must maintain batch records demonstrating compliance with a REACH intermediate exemption where the substance is not isolated as a standalone product but consumed within the same site’s agrochemical synthesis block. When Triazole‑Thiazole Hybrid Scaffolds Enable SDHI Fungicide Activity in Cereal Seed TreatmentsThe stereoelectronic profile of 5‑methyl‑1,2,4‑triazolo[3,4‑b]benzothiazole aligns favourably with the binding pocket of fungal succinate dehydrogenase, particularly when the methyl group occupies a hydrophobic sub‑pocket that would otherwise be vacant in the unsubstituted analogue. Process‑scale synthetic routes exploit this feature by keeping the amine intermediate in a stable hydrochloride salt until immediately before nucleophilic acylation, thereby preventing oxidative dimerisation that would reduce the yield below 70%. A typical workflow inside a multipurpose API‑compliant plant includes a 2,000 L Hastelloy C‑22 reactor charged with the hydrochloride, neutralised with sodium carbonate to pH 7.0–7.5, and then combined with the dissolved acid chloride at a controlled feed rate that maintains the internal temperature at 25 ± 2 °C. After 6 h of agitation, the slurry is centrifuged through a pressure Nutsche filter, washed with deionised water of conductivity <5 μS/cm, and dried on a double‑cone rotary dryer. The resulting off‑white active ingredient is milled on an air‑jet mill (compressed air at 8 bar, nozzle angle 20°) to produce a technical concentrate with a d90 below 5 µm. This particle‑size distribution ensures suspension homogeneity when the concentrate is later dispersed in water with 4% ethoxylated tristyrylphenol phosphate surfactant to create the ready‑to‑use flowable seed treatment. The commercial formulation is registered under national agricultural regulations requiring a 2‑year storage stability study at 54 °C, with pH drift not exceeding 0.5 units and viscosity below 800 mPa·s at 20 °C and 20 s⁻¹. In product‑stewardship protocols, an analysis certificate referencing the CIPAC MT 184 suspension‑stability method must accompany each batch. Acrylic‑melamine industrial topcoats intended for exterior automotive plastic parts require a UV absorber that resists migration into the bulk polymer and does not generate coloured photodegradation by‑products after 3,000 h of xenon‑arc exposure. A sterically‑hindered 2‑(2‑hydroxyphenyl)‑benzotriazole derivative synthesised from 5‑methyl‑1,2,4‑triazolo[3,4‑b]benzothiazole via a Mannich reaction with p‑cresol and formaldehyde provides a thiomorpholine‑bridge moiety that raises the molecular weight above 500 g/mol, substantially lowering the diffusion coefficient in a thermoset matrix. The intermediate is prepared under a supply‑chain specification requiring a total chlorine content below 50 mg/kg to avoid yellowing. The final UV absorber is incorporated at 1.5–2.5% on total binder solids into a two‑pack hydroxyl‑functional acrylic crosslinked with hexamethoxymethyl melamine. Dispersion into the millbase is performed on a horizontal bead mill (chamber volume 1.8 L, 0.4 mm yttria‑stabilised zirconia beads, tip speed 12 m/s, two passes) until a Hegman gauge reading of 7 is reached. After blending with the letdown clearcoat, the liquid paint is spray‑applied with a 1.2 mm fluid nozzle at 2.5 bar atomising air and baked for 25 min at 140 °C. The finished system is validated according to SAE J2527 (Xenon arc, extended filter) with a Δb∗ below 0.8 at 4,000 kJ/m² radiant exposure, thereby fulfilling the corrosion‑engineering internal standard ASTM D7869. The end‑article is a 40 µm dry‑film clearcoat applied over metallic effect basecoats on injection‑moulded polycarbonate/ABS bumpers and mirror housings. |
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Catalogued under CAS 353764-14-8, the heterocyclic scaffold 5-Methyl-1,2,4-Triazolo[3,4-b][1,3]benzothiazole constitutes a sulfur- and nitrogen-rich fused ring system with a molecular formula of C9H7N3S and a monoisotopic mass of 189.036 Da. The product, supplied as a crystalline solid ranging in color from off-white to pale yellow, finds application as a high-purity building block in medicinal chemistry library synthesis and as an adsorption-type corrosion inhibitor for mild steel in hydrochloric acid pickling baths. Its structural distinction from the parent 1,2,4-triazolo[3,4-b][1,3]benzothiazole lies in the methyl substituent at the 5-position of the benzothiazole ring, which alters the HOMO-LUMO gap and shifts the electrostatic potential distribution across the triazole-thiazole π-system. This modification increases the compound’s inhibition efficiency in acid media by approximately 7–12% relative to the non-methylated analogue at equivalent molar concentrations, as derived from weight loss and electrochemical impedance spectroscopy data obtained under ASTM G1-03 conditions.
Dynamic preparative routes to 5-Methyl-1,2,4-Triazolo[3,4-b][1,3]benzothiazole typically proceed via cyclocondensation of 5-methyl-2-hydrazinobenzothiazole with formic acid or triethyl orthoformate under Dean-Stark reflux. The major process-scale impurity is the 6-methyl regioisomer, formed when the starting benzothiazole bears a methyl substituent that migrates during heterocyclization. Liquid chromatography on a C18 column with acetonitrile/water (60:40 v/v) at 1.0 mL/min resolves the two isomers with a retention time difference of 0.8–1.2 min. Industrial batches intended for structure-activity relationship (SAR) campaigns require an isomeric purity exceeding 99.0 area% at 254 nm; lower purities introduce confounding biological readouts in kinase inhibition assays and GPCR binding panels. Purification via fractional crystallization from ethanol/ethyl acetate (1:3) at –5°C reduces the 6-methyl content below 0.5% in a single recrystallization cycle, though recovery drops to 62–68%. Silica gel flash chromatography with dichloromethane/methanol (98:2) achieves 99.4% purity at 85% recovery, but column loading must not exceed 3.0 g crude per 100 g silica to maintain baseline separation.
Reaction monitoring by 1H NMR (DMSO‑d6, 400 MHz) identifies completion when the hydrazine proton singlet at δ 9.2 disappears and the triazole methine proton appears as a sharp singlet at δ 9.48. The aromatic region displays a doublet at δ 8.10 (J = 8.4 Hz) for the C‑8 proton, with the C‑7 proton shifted downfield to δ 7.52 due to the adjacent methyl group. Deviation of the methine singlet by more than 0.05 ppm from δ 9.48 indicates incomplete ring closure or formic acid ester side-product formation, requiring re-treatment with a 1.5 molar excess of orthoformate at 110°C for 2 hours.
| Parameter | Value / Range | Method |
|---|---|---|
| Appearance | Off-white to pale yellow crystalline powder | Visual inspection under D65 illumination |
| Melting point | 178–182°C | Differential scanning calorimetry, 10 K/min, N2 purge |
| HPLC purity (by area) | ≥99.0% at 254 nm | C18, 5 μm, 250×4.6 mm; MeCN/H2O 60:40 |
| 6-Methyl isomer content | ≤0.3% | Same HPLC system, relative retention time 1.11 |
| Loss on drying | ≤0.5% | 60°C vacuum (10 mbar), 4 h |
| Residual formic acid | ≤50 ppm | Ion chromatography, conductivity detection |
| Solubility (DMSO) | ≥25 mg/mL at 25°C | Gravimetric after 0.45 µm filtration |
| Heavy metals (as Pb) | ≤10 ppm | ICP‑OES, microwave digestion |
Storage under argon at 2–8°C in amber borosilicate vials with PTFE-lined caps preserves HPLC purity within 0.3% of initial certification for 24 months. Exposure to relative humidity above 60% for periods exceeding 8 hours promotes surface hydration that depresses the melting point by 2–3°C and introduces a broad OH stretching band at 3450 cm−1 in FTIR. A pre-drying step at 50°C under oil-pump vacuum for 2 hours reverses this hydration completely.
Electrochemical evaluation of 5-Methyl-1,2,4-Triazolo[3,4-b][1,3]benzothiazole as a mixed-type corrosion inhibitor for AISI 1018 carbon steel follows protocols derived from ASTM G59-97 and ASTM G102-89. When added to 1 M HCl at concentrations of 50–400 ppm, the compound shifts the open circuit potential by less than ±30 mV relative to the uninhibited blank after 1800 seconds of immersion, confirming mixed inhibition behavior. Potentiodynamic polarization scans from –250 mV to +250 mV versus OCP at a sweep rate of 0.5 mV/s yield Tafel slopes that remain parallel across the concentration range, indicating that the inhibitor adsorbs onto active sites without altering the hydrogen evolution or iron dissolution mechanisms. At 200 ppm, the corrosion current density (icorr) drops from 587 µA/cm² (blank) to 48 µA/cm², corresponding to an inhibition efficiency of 91.8% calculated from charge transfer resistance values obtained via electrochemical impedance spectroscopy at 10 mHz to 100 kHz with a 10 mV AC perturbation.
Adsorption isotherm analysis using weight loss data (immersion time 6 hours at 298 K) fits the Langmuir model with an R² value of 0.9993 and an adsorption equilibrium constant Kads of 1.26×10⁴ M−1. The standard free energy of adsorption ΔG°ads computes to –33.4 kJ/mol, indicating a mixed physisorption and chemisorption process where the methyl group enhances hydrophobic film formation on the metal surface while the triazole and benzothiazole nitrogen atoms donate lone-pair electrons to the d-orbitals of iron. X-ray photoelectron spectroscopy of the inhibited steel surface detects a N 1s peak at 399.8 eV, consistent with Fe‑N coordinative bonding, and an S 2p doublet at 163.7 eV that confirms sulfur participation in the protective film. The methyl substituent at the 5-position increases the electron density on the benzothiazole sulfur via an inductive effect, strengthening the S‑Fe bond relative to the unmethylated analogue by an estimated 5–8 kJ/mol based on DFT calculations reported in the corrosion science literature. This translates to a measurable improvement in inhibition durability over 24-hour immersion tests in static acid: the 5-methyl derivative retains 88% efficiency versus 79% for the parent compound under identical conditions.
In contrast to propargyl alcohol-based inhibitors used in oilfield acidizing, this triazolobenzothiazole does not decompose exothermically above 70°C. Thermogravimetric analysis under air shows 5% mass loss only at 235°C, with a sharp decomposition exotherm peaking at 306°C. This thermal stability permits its use in acid cleaning operations at elevated temperatures, although turbulent flow conditions with linear velocities above 2.5 m/s> have been observed to mechanically disrupt the adsorbed film, lowering efficiency to 72–75%.
The compound’s low aqueous solubility (0.18 mg/mL in distilled water at 25°C) necessitates formulation in a co-solvent for field dosing. A solution of 10% (w/v) in diethylene glycol monobutyl ether, dosed at 2.0 mL per liter of 15% HCl, yields an inhibitor concentration of 200 ppm without requiring surfactant micellization. However, combination with amine-based intensifiers such as hexamethylenetetramine leads to precipitation of a 1:1 charge-transfer complex, manifested as orange flocculates that adhere to heat exchanger surfaces and promote under-deposit corrosion. This incompatibility dictates separate injection lines when a multi-component inhibitor package is deployed.
The 5-methyl positional isomer is distinguished from its 6-methyl and 7-methyl counterparts by both chromatographic behavior and biological target selectivity. Against the p38α MAP kinase, the 5-methyl derivative exhibits an IC50 of 0.42 µM in a radiometric filter-binding assay (ATP concentration 100 µM), whereas the 6-methyl isomer is inactive at 10 µM and the 7-methyl isomer displays only 34% inhibition at the same top concentration. This divergence arises because the 5-methyl group occupies a shallow hydrophobic pocket formed by Val38 and Lys53 that cannot accommodate a methyl group oriented toward the 6- or 7-positions without steric clash with the hinge region of the kinase. Molecular docking studies (Glide SP scoring function) place the 5-methyl substituent 3.7 Å from the Cγ atom of Val38, a distance compatible with van der Waals stabilization, while the 6-methyl analogue forces a rotation of the triazole ring that increases the ligand strain energy by 4.1 kcal/mol.
Compared to the chloro-substituted analogue 5-Chloro-1,2,4-Triazolo[3,4-b][1,3]benzothiazole, the methyl derivative offers lower acute toxicity to Daphnia magna in 48-hour immobilization tests (EC50 > 100 mg/L vs. 12.4 mg/L for the chloro derivative), an important consideration when selecting intermediates for large-scale synthesis where aqueous waste streams may contact surface water. The electron-donating character of the methyl group also reduces the susceptibility of the triazole ring to nucleophilic attack by glutathione in hepatic S9 fraction metabolic stability assays, extending the half-life from 18 min to 47 min. In synthetic chemistry applications, the 5-methyl derivative undergoes Suzuki-Miyaura coupling at the unsubstituted C‑7 position with phenylboronic acid in the presence of Pd(PPh3)4 and K2CO3 in dioxane/water at 90°C to yield 7-phenyl-5-methyl derivatives in 71% isolated yield, whereas the 5-chloro analogue requires more forcing conditions (Pd2(dba)3/XPhos, 110°C) due to catalyst poisoning by the chlorine substituent.
For laboratories performing parallel medicinal chemistry, 5-Methyl-1,2,4-Triazolo[3,4-b][1,3]benzothiazole is offered in a pre-weighed 100 mg format in 96-well deep-well plates sealed under nitrogen, eliminating the need for individual vial weighing and reducing hygroscopic sample degradation from repeated container opening. Each well is quality-controlled by LCMS to contain 100 ± 2 mg of compound at ≥99.2% purity, with a plate map included as a printable PDF.
Under the European Chemicals Agency registration framework, this substance falls within the definition of a phase-in substance for REACH purposes depending on the annual tonnage band. No harmonised classification under CLP Regulation (EC) No 1272/2008 has been assigned, but self-classification based on available toxicological data suggests acute oral toxicity Category 4 (H302) and skin irritation Category 2 (H315). Personal protective equipment for handling includes nitrile gloves tested to EN 374-3, safety glasses meeting EN 166, and a locally exhausted fume hood with an average face velocity of 0.5 m/s.
