2,4-Dichloro-1,3-Thiazole

Product Name 2,4-Dichloro-1,3-Thiazole
Alias 2,4-Dichlorothiazole
Einecs 210-454-4
Mininmum Order 1g
Factory Site West Ujimqin Banner, Xilingol League, Inner Mongolia, China
Price Inquiry sales9@bouling-chem.com
Manufacturer Bouling Chemical Co., Limited
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In terms of specification, 2,4-Dichloro-1,3-Thiazole is supplied with ≥98% purity (GC) and ≤0.5% moisture (K.F.), making it suitable for use as a key intermediate in agrochemical and pharmaceutical synthesis.

Specifications

HS Code	491828
Chemical Formula	C3HCl2NS
Molar Mass	168.01 g/mol
Appearance	Solid (usually white or off - white)
Physical State At Room Temp	Solid
Melting Point	Data needed
Boiling Point	Data needed
Solubility In Water	Low solubility
Solubility In Organic Solvents	Soluble in some organic solvents like dichloromethane
Density	Data needed
Odor	Typically has a characteristic chemical odor
Stability	Stable under normal conditions but may react with strong oxidizing agents

As an accredited 2,4-Dichloro-1,3-Thiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

Packing & Storage

Packing	500g of 2,4 - Dichloro - 1,3 - Thiazole packaged in a sealed, chemical - resistant bottle.
Shipping	2,4 - Dichloro - 1,3 - Thiazole is a chemical. Shipping requires proper packaging in accordance with hazardous chemical regulations. It must be labeled clearly, transported by approved carriers, ensuring safe handling throughout the process.
Storage	2,4 - Dichloro - 1,3 - thiazole should be stored in a cool, dry, well - ventilated area, away from heat sources and open flames. Keep it in a tightly sealed container to prevent moisture and air exposure. Store it separately from oxidizing agents, bases, and other incompatible substances to avoid potential chemical reactions.

Application of 2,4-Dichloro-1,3-Thiazole

In the continuous thioetherification–oxidation cascade used to manufacture fluensulfone-type nematicidal active substances, 2,4-dichloro-1,3-thiazole (CAS 4175-79-7) functions as the primary electrophilic platform. The reaction sequence exploited in multi-tonne campaigns at dedicated agrochemical synthesis units relies on the markedly differentiated leaving-group aptitude of the chlorine at the 2-position, which undergoes selective displacement by a pre-formed n-butyl mercaptide nucleophile while the 4-chlorine remains intact for subsequent sulfonyl fluoride activation. In a representative 6,300 L glass-lined stirred-tank reactor fitted with a HCl scrubber loop and rated for –10 °C brine circulation, 1.02–1.08 molar equivalents of sodium butane-1-thiolate in anhydrous tetrahydrofuran are fed below the liquid surface at a rate limited to keep the batch temperature at –3 °C to +1 °C; exotherm exceeding +3 °C accelerates bis-adduct formation at the 4-chloro site, creating a waste stream that can materially shift the site’s total organic carbon load. After aqueous quench and phase cut, the isolated 2-butylthio-4-chlorothiazole intermediate is oxidized with peracetic acid under strictly controlled pH 4.2–4.8 at 18–22 °C to give the sulfone, which is then deprotonated and captured with a pre-cooled olefinic electrophile. The final acylation and chlorination sequence yields fluensulfone (ISO common name; 5-chloro-2-[(3,4,4-trifluorobut‑3‑en‑1‑yl)sulfonyl]-1,3-thiazole) with a typical in-process purity above 96% area by GC-FID before recrystallisation from n-heptane/toluene. Regulatory compliance for this intermediate encompasses a full REACH registration dossier with exposure scenarios covering the sulfonylation spray-drying operation, adherence to the FAO specification 581/TC (December 2021 version) for the technical material, and residue data packages aligned with the JMPR dietary risk assessment framework used to set Codex maximum residue limits. Downstream formulated products are predominantly emulsifiable concentrates at 480 g a.i./L, stabilised with an epoxidised soybean oil co-solvent blend and packaged in fluorinated HDPE containers that have passed the six-week accelerated storage test at 54 °C ± 2 °C per CIPAC MT 46.1. The terminal nematicide is deployed in soil-applied banded treatments for root-knot nematode (Meloidogyne spp.) control in solanaceous crops under drip-fertigation; its registration dossiers also reference the EPA 40 CFR § 180.660 tolerance expression for the combined residues of fluensulfone and its sulfonic acid metabolite.

What Limits Batch Exotherms During Selective Stille Coupling at the 4-Position for BCR-ABL Tyrosine Kinase Inhibitor Intermediates?

In the production of 4‑aryl‑2‑chlorothiazole building blocks destined for ATP‑competitive kinase inhibitors structurally related to dasatinib, the downstream chemistry exploits a palladium‑catalysed cross‑coupling that must respect a narrow thermal window to avoid exothermic decomposition of the thiazole ring. A dedicated manufacturing suite built around a 1,600 L Hastelloy C‑276 reactor with a triple‑pitched retreat‑curve impeller and a cascade jacket split into four independent temperature zones is charged with 1.30 equivalents of the pre‑dried organotin reagent (generally 4‑methyl‑3‑pyridyl tributylstannane content ≥ 97%) and 0.7–1.0 mol% of tetrakis(triphenylphosphine)palladium(0) on a substrate basis. The solid 2,4‑dichloro‑1,3‑thiazole is added as a single portion under an argon sweep verified by a residual oxygen analyser reading ≤ 10 ppm at the vent. N,N‑Dimethylformamide that has been degassed by three pump‑freeze‑thaw cycles and dried over activated 4 Å molecular sieves to a water content below 50 µg/g is introduced at 20–25 °C, and the slurry is then heated with a controlled ramp of 0.8 °C/min to an internal temperature of 78–82 °C. The maximum permitted ΔT between jacket and bulk is 12 °C because any localised overheating above 90 °C initiates an autocatalytic ring‑opening pathway that generates H2S–detectable by on‑line Dräger‑Tube monitoring—and irreversibly fouls the batch. The coupling is run to ≥ 99% conversion of the 4‑chloro site as tracked by inline ReactIR monitoring of the C–Cl stretching band at 1080 cm⁻¹. The crude arylthiazole is then washed with 5% w/w aqueous potassium fluoride to remove tributyltin chloride and recrystallised from isopropanol/water (70:30 v/v) to reach ≥ 99.5% chromatographic purity. The governing quality framework is ICH Q7 for active pharmaceutical ingredient starting materials with a clear designation of the GMP‑starting point immediately after this isolated intermediate; all batches must be tested for elemental impurities against the ICH Q3D Option 2A intake limits (oral PDE, palladium ≤ 100 µg/day, tin ≤ 600 µg/day) using a validated ICP‑MS method aligned with USP ⟨233⟩. Residual solvents are controlled per USP ⟨467⟩ Procedure A, with an additional internal cap of 100 ppm for DMF in the final intermediate shipped to the drug‑product manufacturer. The terminal API, a 2‑aminothiazole‑5‑carboxamide generated after sequential ammonolysis and acylation, is micronised to a particle size D₉₀ of ≤ 5 µm and formulated as film‑coated tablets at a unit dose strength of 20 mg or 50 mg for the oncology indication.

Class 1 and 2A Elemental Impurity Limits Applied to the 4-Aryl Intermediate (μg/g relative to API)
Element	ICH Q3D Oral PDE (μg/day)	Intermediate Limit (μg/g) for 50 mg dose	Test Method
Pd	100	2000	USP ⟨233⟩ ICP‑MS
Sn	600	12000	USP ⟨233⟩ ICP‑MS
Ni	200	4000	USP ⟨233⟩ ICP‑MS
As	15	300	USP ⟨233⟩ ICP‑MS

High-Washfastness Monoazo Disperse Dye Scaffolds Derived from 2‑Amino‑4‑chlorothiazole

Polyester coloration for automotive interior fabrics and outdoor technical textiles demands chromophores that combine high sublimation fastness with resistance to repeated ISO 105‑C06 E2S wash cycles, and a family of monoazo disperse dyes built on a 2‑amino‑4‑chlorothiazole diazo component has been engineered to meet those strict tolerances. The route vector utilises 2,4‑dichloro‑1,3‑thiazole as the starting building block, which is converted to the heterocyclic amine by controlled ammonolysis with 3.5–4.0 equivalents of 28% w/w aqueous ammonium hydroxide in a pressure‑tight stainless‑steel autoclave at 105 °C and an autogenous pressure of 2.1–2.4 bar. After stripping of ammonia and vacuum distillation (95–98 °C at 12 mmHg), the isolated 2‑amino‑4‑chlorothiazole—fused with ninhydrin test for completeness of amination—is taken into the diazotisation step without further purification. The diazo bath is prepared by dissolving the amine in 85% w/w phosphoric acid and adding solid sodium nitrite (1.04–1.07 molar equivalents) portionwise at –5 °C to 0 °C; the slight molar excess of nitrite is back‑titrated with sulfamic acid immediately before coupling in order to suppress nitrosamine formation. Coupling to an N‑substituted aniline coupler—most often 2‑methoxy‑5‑acetylamino‑N,N‑diethylaniline—is carried out in an ice‑water suspension at pH 1.5–2.2, then the slurry is neutralised to pH 4.0 with sodium acetate, filtered, and washed with demineralised water until the conductivity of the filtrate falls below 50 µS/cm. The presscake is dried in a vacuum shelf dryer at 60 °C and a residual pressure ≤ 50 mbar until the moisture content reaches ≤ 0.5% w/w. In the standard commercial disperse dye formulation, this chlorothiazolyl‑azo dye constitutes between 2.5% and 5.0% of the total colourant, which is extended with lignin sulfonate dispersants and subjected to bead milling to a primary particle size D₅₀ of 0.8–1.2 µm. Methylene‑chloride stripping of the dried product is monitored to ensure residual solvent levels comply with the OEKO‑TEX Standard 100 Annex 4 restricted‑substances list, while the absence of the 24 aromatic amines listed in REACH Annex XVII, entry 43, is confirmed by GC‑MS after reductive cleavage, following the EN ISO 14362‑1:2017 protocol. The formulated dye is shipped to polyester yarn package‑dyeing houses, where it is applied by high‑temperature exhaust at 130–135 °C to achieve deep navy shades with a ΔE colour difference ≤ 0.8 CIE Lab units between batch lots.

When Trifluoromethylthiolation Replaces Alkylation in Thiazole Carboxanilide Fungicide Production

Succinate‑dehydrogenase‑inhibitor fungicides that carry a thiazole‑carboxamide pharmacophore, exemplified by thifluzamide, are accessed industrially through a route that inserts the trifluoromethylthio (SCF₃) moiety into the thiazole ring using 2,4‑dichloro‑1,3‑thiazole as the halogen‑bearing scaffold. In a typical manufacturing sequence documented in the non‑public section of OECD max. daily dose studies, the SCF₃ group is introduced by treating the substrate with 1.50–1.65 equivalents of cuprous trifluoromethylthiolate (CuSCF₃) synthesised in situ from silver fluoride, carbon disulfide, and copper(I) bromide in N‑methyl‑2‑pyrrolidone. The substitution is carried out in an anhydrous acetonitrile slurry within a 3,000 L glass‑lined reactor operating under a nitrogen cap that maintains an oxygen headspace concentration below 0.3% v/v. Because the CuSCF₃ decomposition pathway becomes exothermic above 62 °C, the addition of the copper reagent is conducted in five equal portions while the jacket is held at 45 °C, and the reaction mass is allowed to self‑heat to a plateau of 57–60 °C after each addition; a runaway scenario triggered by miscalibrated thermocouples has been a root cause of several reported thermal incidents in toll‑manufacturing campaigns. The selectivity for the 2-position substitution exceeds 20:1 over the 4-chloro site, verified by ¹⁹F NMR integration of the crude mixture. Following aqueous workup and drying, the intermediate 2‑trifluoromethylthio‑4‑chlorothiazole is converted to the corresponding carboxylic acid through magnesium‑halogen exchange with isopropylmagnesium chloride‑lithium chloride complex at –20 °C followed by carbonation on solid CO₂ pellets; any trace moisture in the CO₂ stream pushes the carboxylation yield below the economic breakeven point of 85%. The resulting 2‑trifluoromethylthio‑1,3‑thiazole‑4‑carboxylic acid is then coupled with 2,6‑dibromo‑4‑trifluoromethoxyaniline using thionyl chloride activation in toluene at 80 °C to furnish thifluzamide technical. The agrochemical regulatory submission references FAO specification 581/TC (August 2017 revision), which requires the active ingredient content to be ≥ 960 g/kg and the sum of unidentified impurities to remain ≤ 10 g/kg. Production‑scale quality control additionally enforces a critical shelf‑life check: after 14‑day storage of the technical material at 54 °C ± 2 °C in laminated polyethylene‑aluminium bags, the average percent recovery must be ≥ 95% and the suspended matter in a 10% w/v acetone extract must not exceed 0.1 g/100 mL to prevent nozzle blockage in low‑volume air‑blast sprayers. Formulated end‑use products are typically 240 g/L suspension concentrates containing ethoxylated tristyrylphenol wetting agents and xanthan gum rheology modifiers, applied at a field rate of 140–280 g a.i./ha for sheath blight control in transplanted rice.

Thermal Stability Profile of the CuSCF₃ Substitution Reaction (calorimetric data at 1.5 eq. CuSCF₃)
Parameter	Value	Instrument Configuration
Onset temperature of exotherm	63 °C ± 2 °C	Mettler Toledo RC1mx, glass vessel
Maximum heat flow	42 W/kg	Tr mode, TR/TJ = 15 K
Adiabatic temperature rise (ΔT_ad)	104 K	Calculated via heat‑capacity correction
Time to maximum rate under adiabatic conditions	4.2 h at 60 °C start	ARC screening test, phi‑factor 1.15
Recommended process safety spacing	Maintain jacket ≤ 45 °C; stop addition if bulk ≥ 61 °C	—

In the precipitation of silver halide tabular grains for high‑speed colour negative film and aerial reconnaissance emulsions, an entire subclass of organic thiazole derivatives generated from 2,4‑dichloro‑1,3‑thiazole has historically served as fog suppressants and chemical sensitisation stabilisers that do not perturb the iodide‑rich core‑shell epitaxy. The key transformation is a selective mercapto‑exchange carried out in a dedicated photographic‑grade facility: an aqueous‑ethanolic solution of the thiazole is treated with 1.05 equivalents of sodium hydrogen sulfide at pH 7.8–8.2 and 35 °C to yield 2‑mercapto‑4‑chlorothiazole, a ligand that binds preferentially to the (111) silver halide crystal face during the Ostwald ripening phase. The compound is purified by multiple recrystallisations from de‑oxygenated water under dim‑red safe‑light to a level where the trace iron and copper content measured by GFAAS is ≤ 0.5 µg/g for each element—a requirement specified in the internal sensitometric specification sheets of film manufacturers that correlated metal contamination with raw‑stock fog increase. Addition rates to the kettle after the sulfur‑and‑gold chemical sensitisation step are typically in the range of 15–50 mg of the fused thiazole per mole of silver, introduced as a 0.1% w/v methanol solution from a syringe pump at a constant rate over 10 minutes while the pAg is maintained strictly at 8.2 ± 0.05 by controlled double‑jet addition of AgNO₃ and NaBr. Deviation below pAg 8.1 strips the stabiliser from the grain surface and leads to an increase in minimum density (D_min) that exceeds the acceptable 0.03 optical density unit shift in the blue channel of a Status M densitometer. Stability of the emulsion additive concentrate is verified against ISO 18902:2013 by incubating sealed amber vials under 50% RH at 40 °C for 28 days and confirming ≤ 5% loss of active thiol titer via iodometric back‑titration. The finished photographic material—whether 35 mm colour negative film in 135 format or 240 mm roll‑fed aerial duplicating stock—carries a latent image keeping that is maintained within ± 0.10 log E speed change over 24 months of refrigerated storage. Technical support notes from film‑coating plants further document that batches of 2‑mercapto‑4‑chlorothiazole failing the gel‑permeation cut‑off test with a molecular‑weight shoulder below 150 Da produced banding artifacts on the coated web, correlating with residual chloride‑bridged dimer formation during mercaptide condensation.

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Certification & Compliance

2,4-Dichloro-1,3-Thiazole is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales9@bouling-chem.com.

More Introduction

In research and industrial synthesis, 2,4-dichloro-1,3-thiazole (CAS 4175-76-2) is supplied as a pale yellow to white crystalline solid with a melting point typically in the range 41–43 °C and a boiling point of approximately 195–197 °C at atmospheric pressure. Standard commercial specifications demand a purity of ≥98.0% (GC, in-house method modelled on ASTM D3465) and water content ≤0.5% (Karl Fischer titration per ASTM E203-16). The heterocycle belongs to the 1,3-thiazole family and is distinguished by two chlorine substituents at the 2‑ and 4‑positions, conferring a dual‑handle architecture that supports sequential, regiocontrolled derivatisation. As an intermediate, it serves primarily in agrochemical and pharmaceutical discovery programmes, and its handling characteristics—hygroscopicity, sensitivity to strong bases, and the thermodynamic preference for nucleophilic attack at C‑2—define its utility relative to other halogenated thiazole isomers.

What Synthetic Strategies Leverage the Regioselective Displacement of Chlorine in 2,4-Dichlorothiazole?

The 2‑chloro substituent is activated by the annular nitrogen through a formal S_NAr manifold; primary and secondary aliphatic amines displace it cleanly in tetrahydrofuran or dichloromethane at temperatures between 0 °C and 25 °C. Reaction with 1.05 eq of n‑butylamine yields exclusively 2‑(n‑butylamino)-4-chlorothiazole in isolated yields exceeding 85%, as confirmed by ¹H NMR and HPLC. The residual 4‑chlorine is significantly less electrophilic: its displacement by the same amine requires heating to 80–100 °C in dimethylformamide and proceeds with a regioselectivity of >20:1 in favour of the 2‑position when both sites are free. This orthogonal reactivity allows the thiazole ring to be elaborated stepwise—first at C‑2 via nucleophilic substitution, and subsequently at C‑4 via palladium‑catalysed cross‑coupling or, in some cases, a second S_NAr event under forcing conditions. Steric bulk in the nucleophile can erode the regiochemical fidelity. tert‑Butylamine, for example, gives a diminished selectivity of approximately 4:1 (2‑substituted vs. bis‑adduct) due to increased steric interaction with the 4‑chloro substituent, a limitation that must be managed by slow addition at −10 °C and use of a polar aprotic solvent such as N,N‑dimethylacetamide to retard the formation of the over‑reacted by‑product. Residual 4‑chlorothiazole intermediates have been further functionalised by Suzuki–Miyaura coupling with arylboronic acids using Pd(PPh₃)₄ and K₂CO₃ in dioxane/water at 90 °C, as well as by Sonogashira alkynylation with terminal acetylenes in the presence of CuI and PdCl₂(PPh₃)₂. The compound is incompatible with strong alkoxide bases at elevated temperatures; attack at the C‑2 position can be followed by ring opening when the thiazole is treated with sodium methoxide at reflux, a pathway exploited deliberately for the preparation of α‑aminothioacetals but which must be avoided when the intact heterocycle is the target. In the synthesis of the fungicide ethaboxam, 2,4-dichlorothiazole serves as the cornerstone building block. A patent‑described cyanation step (for instance, WO 98/46608) treats the dichloride with zinc cyanide in dimethylformamide at 120 °C in the presence of Pd₂(dba)₃ and 1,1′‑bis(diphenylphosphino)ferrocene (dppf) to afford 2‑cyano‑4‑chlorothiazole in 88% isolated yield. On pilot‑plant scale in a 200 L glass‑lined reactor, the reaction exotherm requires jacket temperature control to within ±2 °C of the set point; deviation beyond 125 °C leads to rapid conversion to the corresponding amide, which consumes cyanide transfer reagent and renders the batch unrecoverable. The crude stream is typically quenched into aqueous ammonia to complex residual zinc and is then extracted with toluene. The organic phase is washed with chelating agents, and the product is crystallised from heptane to achieve a purity of >99.5%, a prerequisite for the subsequent acylation that forms the ethaboxam scaffold. Moisture ingress during the cyanation—often from inadequately dried zinc cyanide or DMF with water content exceeding 100 ppm—promotes nitrile hydrolysis and reduces isolated yield by up to 12%, requiring activated molecular sieve drying of solvents and reagent pre‑drying at 60 °C under vacuum.

Impurity Profiling and Assay Verification under ICH Q3A Guidelines

Regulatory starting material specifications for pharmaceutical intermediates derived from 2,4‑dichlorothiazole mandate tight impurity control. A typical reversed‑phase HPLC method (C18 column, acetonitrile/water mobile phase with 0.1% trifluoroacetic acid, detection at 254 nm) resolves the parent compound from its common low‑level impurities. The acceptance criteria for a material released to cGMP manufacturing are summarised below.

Impurity	Relative Retention Time (vs. parent)	Acceptance Criterion
2‑Chlorothiazole	0.78	≤ 0.15%
2,4,5‑Trichlorothiazole	1.32	≤ 0.10%
2,4‑Dichlorothiazole‑5‑carboxylic acid	0.45	≤ 0.10%
Any unspecified impurity	—	≤ 0.10%
Total impurities	—	≤ 0.5%

Quantitation is performed against a certified reference standard of known purity, and system suitability is verified with a resolution solution ensuring baseline separation of 2‑chlorothiazole and 2,4‑dichlorothiazole (resolution factor ≥2.0). Batches that fail the unspecified impurity threshold are reprocessed by recrystallisation from hexane/ethyl acetate mixtures; the recrystallisation mother liquors can concentrate the trichlorinated species to levels above 0.5%, making a single‑stage crystallisation insufficient for remediation.

When 2,4-Dichlorothiazole Replaces 2,5-Dichlorothiazole in Palladium-Catalysed Amination

The isomeric 2,5‑dichlorothiazole (CAS 4175-79-7) differs fundamentally in reactivity because the 5‑chlorine lies in a position that is much less activated toward nucleophilic substitution. Whereas 2,4‑dichlorothiazole offers a pair of orthogonal handles—the 2‑chlorine for S_NAr and the 4‑chlorine for metal‑catalysed coupling—the 2,5‑isomer exhibits only a single electrophilic centre at C‑2 under typical conditions. Attempts to displace the 5‑chlorine in 2,5‑dichlorothiazole with amines require extreme conditions (e.g., potassium amide in liquid ammonia) that frequently lead to decomposition. A comparative overview of the two dichlorothiazole isomers and the monochlorinated analogue is provided.

Parameter	2,4-Dichlorothiazole	2,5-Dichlorothiazole	2-Chlorothiazole
Melting point	41–43 °C	−6 to −4 °C	−21 °C
Boiling point (760 mmHg)	195–197 °C	188–190 °C	145–147 °C
Position of facile S_NAr	C‑2	C‑2 (C‑5 inert)	C‑2 only
Cross‑coupling accessibility	C‑4 via Pd after C‑2 substitution	Limited; homo‑coupling pathway prevalent	N/A (monofunctional)
Typical order of use in discovery libraries	Tier‑1 scaffold for two‑directional elaboration	Used where 5‑substitution is pre‑installed before thiazole formation	Simple placeholder for 2‑substituted thiazoles

This reactivity gap explains the dominance of the 2,4‑dichloro isomer in medicinal chemistry campaigns that require a modular entry point for structure–activity relationship exploration. When a 5‑substituent is desired, chemists typically construct the thiazole ring with the required substituent already in place rather than attempting late‑stage functionalisation of 2,5‑dichlorothiazole, unless metal‑catalysed C–H activation on a 2‑substituted thiazole is employed. Storage and handling protocols demand that 2,4‑dichlorothiazole be kept in tightly sealed containers under an inert nitrogen atmosphere, protected from moisture. Prolonged exposure to relative humidity above 60% at 25 °C induces hydrolysis, releasing HCl and leading to a measurable drop in purity within 48 hours. The recommended storage temperature is 2–8 °C; material that has been subjected to freeze‑thaw cycling should be pre‑dried in a vacuum oven at 30 °C for 4 hours before use. The compound is REACH‑registered under EC number 224-065-3, and its transport classification falls under UN 3077 (Environmentally Hazardous Substance, Solid, n.o.s.) in pack‑group III, requiring spill containment and avoidance of release to waterways.