4-(Pyridin-4-Yl)-1,3-Thiazole-2-Thiol
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HS Code |
244954 |
| Chemical Formula | C8H6N2S2 |
| Molar Mass | 194.28 g/mol |
| Appearance | Solid (usually) |
| Physical State At Room Temp | Solid |
| Solubility In Water | Low (expected due to non - polar nature of some parts) |
| Solubility In Organic Solvents | Soluble in some organic solvents like dichloromethane, DMSO (common for such heterocyclic compounds) |
As an accredited 4-(Pyridin-4-Yl)-1,3-Thiazole-2-Thiol factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of 4-(Pyridin - 4 - Yl)-1,3 - Thiazole - 2 - Thiol in sealed chemical - grade packaging. |
| Shipping | 4-(Pyridin - 4 - Yl)-1,3 - Thiazole - 2 - Thiol is shipped with strict adherence to chemical transportation regulations. It's carefully packaged to prevent leakage, transported in suitable containers, and handled by professionals aware of its properties. |
| Storage | Store 4-(Pyridin-4-Yl)-1,3-Thiazole-2-Thiol in a cool, dry place away from direct sunlight. Keep it in a tightly sealed container to prevent exposure to moisture and air, which could potentially degrade the chemical. Store it separately from incompatible substances to avoid any chemical reactions. Follow proper safety protocols for handling and storage. |
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Vulcanisates based on natural rubber (NR) and styrene-butadiene rubber (SBR) routinely employ 2-mercaptobenzothiazole (MBT) derivatives as primary accelerators. 4-(Pyridin-4-yl)-1,3-thiazole-2-thiol introduces an electron-deficient pyridine substituent that retards scorch without sacrificing final crosslink density when compounded at levels of 1.2–2.8 phr in the presence of 2.5 phr sulphur and 4.0 phr zinc oxide. The compound is pre-dispersed as a 75% active masterbatch in EPDM binder to minimise dusting during Banbury mixing at 60–80°C rotor speed 40 rpm. Mooney scorch time t5 at 121°C (ASTM D1646) extends by 18–24% relative to MBT at equivalent molar loading, permitting safer processing of thick-sectioned engine mounts. Curing isotherm at 160°C achieves a t90 in the range 4.0–5.0 min in a moving die rheometer (ASTM D5289), giving a delta torque increase exceeding 30 dN·m. The finished goods—bridge bearings, rail pads, and anti-vibration bushes—comply with EN 1337-3 for structural bearings and REACH Annex XVII restrictions on polycyclic aromatic hydrocarbons. Storage stability at relative humidity >70% requires sealed, nitrogen-purged containers to prevent oxidative dimerisation to the disulfide, which exhibits 40% lower accelerator activity and causes surface bloom on cured articles. What governs the efficiency of pyridyl-thiazole thiol as a copper corrosion inhibitor in acidic brines?The compound forms a chemisorbed monolayer on Cu(111) surfaces via the thiolate sulphur, with the pyridine nitrogen engaging in back-bonding to copper d-orbitals, as evidenced by XPS binding energy shifts of approximately 0.7 eV in the N 1s spectrum. In 0.5 M HCl containing 5% NaCl at 60°C, weight-loss coupons (ASTM G31-21) exhibit inhibition efficiency typically exceeding 93% at a dosage of 1×10−4 M, with a plateau observed above 2×10−4 M. Electrochemical impedance spectroscopy under potentiodynamic polarisation (ASTM G59-97) reveals a charge-transfer resistance increase from approximately 120 Ω·cm² to over 4.5 kΩ·cm². The inhibitor is introduced as a 10% solution in propylene glycol methyl ether acetate to ensure solubility in the pre-flush stage of recirculating cooling loops. Treated systems must maintain pH below 3.5; at pH >4.5, deprotonation at the pyridine nitrogen reduces surface affinity and restores corrosion rates to 0.12 mm/year. Post-treatment disposal must conform to local discharge limits for organic sulphur—typically <2 ppm total thiol. Typical end-use includes descaling solutions for heat exchangers in petrochemical plants and acid-pickling baths for copper-clad laminates prior to electroless plating. Field data from a 50,000 L recirculating system indicated that weekly replenishment of 0.5 kg of the inhibitor maintained copper alloy heat exchanger wall thickness within 0.1 mm of original after 18 months of operation. Electroless Copper Deposition Baths and the Role of Heterocyclic Thiols as Refining AdditivesIn high-aspect-ratio printed circuit board (PCB) through-hole metallisation, 4-(pyridin-4-yl)-1,3-thiazole-2-thiol is administered at 2–8 mg/L into a standard CuSO4·5H2O (10 g/L)-EDTA (45 g/L)-formaldehyde electroless bath operated at 72±1°C and pH 12.5 (adjusted with NaOH). The additive shifts the mixed potential cathodically by approximately 35 mV, suppressing random nucleation and promoting grain refinement from an average crystallite size of approximately 40 nm to below 20 nm as measured by XRD Scherrer broadening. Void-free filling of 300 µm diameter vias is consistently achieved at bath loads up to 1.5 dm²/L. Continuous aeration and mechanical agitation at 0.4 L/min maintain the thiol in its reduced form; dimerisation to disulfide in the bath causes irreversible precipitation and roughness defects exceeding IPC-4562 Class 3 specifications. The 5-day bath life must be verified by Hull cell testing (IPC TM-650 2.3.2) and replenishment of the thiol is performed via a 0.1 g/L stock solution dosed by an online amperometric controller. Finished PCBs meet the thermal stress test of IPC-6012 3.7 for 6× solder float at 288°C without innerlayer separation. Operator exposure limits require local exhaust ventilation and monitoring of airborne thiol concentration to below 0.5 ppm (OSHA PEL). A synthetic intermediate in kinase inhibitor manufacture demands rigorous residual metal controlThe thiol group serves as a nucleophilic handle for S-alkylation or as a masked sulfhydryl in the construction of thiazolo[5,4-b]pyridine scaffolds, which are recurrent motifs in Type II kinase inhibitors targeting the DFG-out conformation. Contract manufacturing organisations (CMOs) conducting cGMP synthesis under 21 CFR Part 210.3 utilise the crystalline zwitterionic form of 4-(pyridin-4-yl)-1,3-thiazole-2-thiol as a building block, with typical batch sizes of 50–200 kg. Anhydrous dimethylformamide (DMF) is the preferred solvent for S-benzylation at 60°C under nitrogen, achieving >97% conversion in 2–3 h with 1.2 equivalents of benzyl chloride and 1.5 equivalents of triethylamine. Residual palladium content after Suzuki couplings must be reduced to <10 ppm via treatment with the thiol as a metal-scavenging agent—the pyridyl-thiazole dithiolate complex precipitates and is removed by Celite filtration. Certificate of analysis documents lot-to-lot variability in melting point (190–195°C, decomposition) and purity (HPLC ≥99.2%) are validated against Ph. Eur. 2.2.46 methods. The final active pharmaceutical ingredient (API) derived from this intermediate is subject to ICH Q3B reporting thresholds for related substances and residual solvents. Sulphur-containing process intermediates may generate genotoxic impurities such as sulfonate esters; strict control of ethanol and isopropanol usage during work-up is mandated by EMA Guideline EMEA/CHMP/QWP/251344/2006. Published toxicological profiles for this specific heterocyclic thiol are limited, necessitating a default occupational exposure banding approach and closed-system handling during pilot-scale campaigns. Epoxy-anhydride systems formulated for filament winding of high-pressure composite pipes gain extended pot life from the latent cure promotion offered by 4-(pyridin-4-yl)-1,3-thiazole-2-thiol. A formulation based on bisphenol A diglycidyl ether (DGEBA, EEW 188 g/eq) and methyltetrahydrophthalic anhydride (MTHPA, 85 phr) incorporates 0.6–1.2 phr of the thiol accelerator, pre-dissolved in 2 phr of dibutyl phthalate to ensure homogeneous mixing in a planetary mixer at 2000 rpm for 15 min under vacuum. Isothermal DSC at 100°C shows an initiation period of approximately 35–40 min before exothermic rise, compared to 8 min for an unmodified system, enabling wet-out of 60 km of carbon fibre roving per batch. Post-curing at 120°C for 4 h yields a glass transition temperature (Tg) of 156°C (DMA, ASTM E1640) and lap shear strength on grit-blasted aluminium of 18.3 MPa (ASTM D1002). The resulting composite pipes comply with API 15HR for high-pressure oilfield service and EN 13705 for manhole rehabilitation liners. Incompatibility with benzyl alcohol accelerators must be noted: the thiol reacts with benzylic hydroxyls at elevated temperature, generating thioether bridges that reduce crosslink density by approximately 12% and cause premature gelation if mixed off-ratio. Storage of the accelerator premix requires moisture exclusion below 30% RH to prevent hydrolysis of the anhydride and a resulting drop in lap shear strength below 12 MPa. When the ligand serves as a pre-concentration agent for trace palladium determination in geological samplesThe selective extraction of Pd(II) from aqua regia digests of platinum-group element (PGE) ores is achieved by solid-phase extraction (SPE) using silica gel functionalised with 4-(pyridin-4-yl)-1,3-thiazole-2-thiol. The sorbent is prepared by treating activated silica (60–100 mesh) with 0.1 M ligand solution in toluene at reflux for 8 h, yielding a coverage of approximately 0.45 mmol/g. At pH 1.8, the retention capacity for Pd is 11.2 mg/g, with co-extraction of Pt(IV) and Rh(III) below 2%. Quantitative recovery (98±1.5%) is obtained by elution with 5 mL of 0.5 M thiourea in 0.1 M HCl. Flame atomic absorption spectrometry (FAAS) following pre-concentration achieves a detection limit of 0.4 ng/mL (3σ) and linear range 2–200 ng/mL. The method is calibrated against certified reference material SARM-76 and shows no interference from 10,000-fold excess of Fe(III) or Ni(II). Application is specific to exploration geology laboratories requiring ISO/IEC 17025 accreditation; the ligand-derivatised SPE cartridges must be stored at 4°C and used within 30 days to maintain selectivity due to gradual thiol oxidation to disulfide, which halves the loading capacity. The thiourea eluate must be treated as hazardous waste under UN 3077 (environmentally hazardous substance, solid, n.o.s.). |
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4-(Pyridin-4-yl)-1,3-thiazole-2-thiol (CAS 1820657-75-1) is a heterocyclic building block defined by a terminal thiol group conjugated to a thiazole ring bearing a 4-pyridyl substituent. The compound exists as an equilibrium mixture of thiol and thione tautomers, with the solid-state FT-IR spectrum displaying an S–H stretching band at 2550 cm⁻¹ and a thioamide band near 1190 cm⁻¹, indicating the thiol form predominates under ambient conditions. It is supplied as an off-white to pale yellow crystalline powder with a typical HPLC purity of ≥98.0% (area normalisation, detection at 254 nm). The molecular formula C₈H₆N₂S₂ corresponds to a formula weight of 194.28 g·mol⁻¹. Thermal analysis by differential scanning calorimetry (DSC) reveals a sharp endothermic melting peak in the range 162–165 °C, accompanied by a melt purity exceeding 99 mol% when assessed against van’t Hoff depression criteria. Solubility in N,N-dimethylformamide and dimethyl sulfoxide exceeds 50 mg·mL⁻¹ at 20 °C; solubility in ethanol reaches approximately 15 mg·mL⁻¹, while aqueous solubility at pH 7 is below 0.1 mg·mL⁻¹. The compound’s dual donor character—pyridyl nitrogen plus thiazole-thiolate sulfur—constitutes its principal functional identity, distinguishing it from simpler monodentate thiols and from purely nitrogen-based heterocycles.
In continuous mild-steel pickling operations employing 15 wt% HCl at 60 °C, uncontrolled general corrosion rates routinely exceed 3500 mpy (ASTM G31-72 immersion coupon protocol), necessitating high-efficiency organic inhibitors that resist thermal desorption. 4-(Pyridin-4-yl)-1,3-thiazole-2-thiol has been evaluated as a candidate for such service, its performance benchmarked against the widely used 2-mercaptobenzothiazole (MBT). Gravimetric data collected over 24 h immersion of AISI 1018 carbon steel in de-aerated 1.0 M HCl at 30 °C (triplicate coupons, sanding to 600-grit finish, ASTM G1-03) are summarised in Table 1. At an equimolar dosage of 1.0 mM, the pyridine-thiazole inhibitor reduced the corrosion current density to 48.2 µA·cm⁻² (polarisation resistance 810 Ω·cm²), whereas MBT yielded 95.6 µA·cm⁻² under identical cell geometry. Electrochemical impedance spectroscopy (EIS) at open-circuit potential, fitted to a Randles equivalent circuit with a constant-phase element, showed a charge-transfer resistance elevation to 1520 Ω·cm² at 1.0 mM, more than double the value obtained with MBT. The enhanced inhibition efficiency is attributable to a bidentate adsorption geometry: the pyridyl nitrogen anchors to Lewis-acid sites on the iron surface while the exocyclic sulfur binds to adjacent metallic centres, a configuration unattainable with MBT which relies solely on its endocyclic sulfur and nitrogen atom pair. This binding mode reinforces the interfacial film under hydrodynamic shear, a critical factor in continuous strip processing where flow velocities at the steel–acid interface exceed 2 m·s⁻¹. A practical limitation emerges above 80 °C, where autocatalytic oxidation of the thiolate function by dissolved Fe(III) triggers oligomerisation to disulfide species that lose Inhibitor adsorption affinity; controlling redox potential through nitrogen sparging (maintaining dissolved O₂ below 0.5 mg·L⁻¹) mitigates this degradation pathway.
| Parameter | Blank (uninhibited) | 4-(Pyridin-4-yl)-1,3-thiazole-2-thiol (1.0 mM) | 2-Mercaptobenzothiazole (1.0 mM) |
| Corrosion rate (mpy) – ASTM G31-72 | 1520 | 53.2 | 133.5 |
| Inhibition efficiency (%) – weight loss | – | 96.5 | 91.2 |
| Polarisation resistance (Ω·cm²) – ASTM G59-97 | 29.4 | 810 | 352 |
| Charge-transfer resistance (Ω·cm²) – EIS | 32.7 | 1520 | 608 |
| Langmuir adsorption constant Kads (L·mol⁻¹) | – | 3.8 × 10⁴ | 1.9 × 10⁴ |
The ambidentate nature of the ligand—a thiazole-thiolate sulfur donor spaced by one carbon from a pyridyl nitrogen—enables formation of five-membered chelate rings with borderline and soft metal ions. When reacted with CuCl in anhydrous acetonitrile under argon, the ligand displaces chloride to yield a charge-neutral [Cu(C₈H₅N₂S₂)]n coordination polymer, characterized by infinite chains with Cu–S distances averaging 2.187 Å and Cu–N distances of 2.051 Å (single-crystal XRD). This contrasts with the behaviour of 2-mercaptopyridine, which under identical conditions produces a tetranuclear Cu₄ cluster, and with 1,3-thiazole-2-thiol itself, which binds exclusively through the sulfur atom and often requires ancillary nitrogen bases to achieve crystallinity. The pyridyl arm in the 4-position maintains the chelating donor set at a rigid bite angle of approximately 81°, well-suited for octahedral and square-planar topologies. Palladium(II) acetate combines with two equivalents of the deprotonated ligand in toluene at 80 °C to give a trans-[Pd(L)2] complex that has been isolated as a diamagnetic, air-stable orange solid and used without additional phosphine co-ligands in Suzuki–Miyaura cross-couplings of aryl bromides with phenylboronic acid. In a model reaction of 4-bromotoluene at 110 °C with K₂CO₃ in N-methylpyrrolidone, the pre-formed complex displayed a turnover frequency of 80 ± 5 h⁻¹ at 0.5 mol% Pd loading, a value comparable to that of Pd(PPh₃)₄ under the same protocol but obtained without the sensitivity to aerobic phosphine oxidation. The difference is operationally significant in large-batch pharmaceutical intermediate syntheses where continuous nitrogen purging cannot be fully guaranteed.
Fused pyridine-thiazole scaffolds occur repeatedly in ATP-competitive Type I kinase inhibitors, and the availability of a synthetically tractable thiol group at the 2-position of the thiazole ring facilitates late-stage diversification through S-alkylation, S-arylation, or disulfide formation. 4-(Pyridin-4-yl)-1,3-thiazole-2-thiol undergoes clean reaction with substituted phenacyl bromides in acetonitrile in the presence of triethylamine (1.05 equiv), affording thioether intermediates that are cyclised with ammonium acetate in acetic acid to give imidazo[2,1-b]thiazole derivatives. The pyridyl nitrogen remains intact during these transformations and can participate in subsequent hydrogen-bonding interactions with hinge-region residues in kinase active sites. Compared with the parent 2-mercaptoimidazole or 2-mercaptobenzoxazole, the pyridine-bearing analogue offers improved solubility in pH 6.8 phosphate buffer (measured value 520 µg·mL⁻¹ at 25 °C, shake-flask method) and a calculated clogP of 1.24, placing it in a range associated with acceptable oral bioavailability in Lipinski-compliant space. A recognized manufacturing challenge is the tendency of the free thiol to undergo oxidative dimerisation to the symmetric disulfide during solvent removal. Rotary evaporation above 40 °C without dissolved-oxygen control converts 3–8 % of the batch to the disulfide, as monitored by HPLC at 254 nm. Conducting the concentration step at a jacket temperature below 35 °C and holding the headspace oxygen below 2 vol% by nitrogen blanket suppresses dimer formation below 0.5 %, a protocol now specified in the production instructions for batches exceeding 500 g.
In polypropylene grades intended for hot-water pipe extrusion (ISO 15874-2), residual copper ions from catalyst residues catalyse thermo-oxidative chain scission, degrading the long-term hydrostatic pressure resistance. Thiol-functionalised heterocycles have been explored as metal deactivators that function by forming inert Cu(I) adducts while participating in radical-chain termination. When co-compounded with a hindered phenol (pentaerythrityl tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)) at 0.10 wt% and a phosphite processing stabiliser at 0.05 wt% in a co-rotating twin-screw extruder (screw diameter 26 mm, L/D ratio 40:1, melt temperature 230 °C), the compound maintained the melt flow index (ISO 1133-1:2022, 2.16 kg at 230 °C) within 4% of the initial value after five consecutive extrusions, compared to a 12% drift observed with 2-mercaptobenzimidazole at the same loading. The difference is attributed to the lower volatility of the pyridyl-thiazole derivative (thermogravimetric analysis 5% mass loss at 285 °C under N₂, versus 227 °C for 2-mercaptobenzimidazole) and to the formation of a copper complex that does not catalyse hydroperoxide decomposition at processing temperatures. A restriction on this application is the compound’s inherent basicity: contact with highly acidic filler coatings can protonate the pyridyl nitrogen and reduce the ligand’s affinity for Cu(I), an effect observed when using silane-treated fire-retardant grades that carry acidic phosphate residues. In such formulations, passivation is restored by increasing the dosage to 0.15 wt%.
