3-Chloro-1,2-Benzisonthiazole
|
HS Code |
536714 |
| Chemical Formula | C7H4ClNS2 |
| Molecular Weight | 187.696 g/mol |
| Appearance | Typically a solid |
| Color | Often white to off - white |
| Odor | May have a characteristic sulfur - containing odor |
| Melting Point | 96 - 98 °C |
| Boiling Point | Decomposes before boiling |
| Solubility In Water | Insoluble in water |
| Solubility In Organic Solvents | Soluble in many organic solvents like ethanol, acetone |
| Density | Approx. 1.48 g/cm³ |
| Stability | Stable under normal conditions, but may react with strong oxidizing agents |
As an accredited 3-Chloro-1,2-Benzisonthiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 500g of 3 - Chloro - 1,2 - Benzisonthiazole packaged in a sealed, chemical - resistant container. |
| Shipping | 3 - Chloro - 1,2 - Benzisonthiazole is shipped in tightly sealed, corrosion - resistant containers. Shipment adheres to strict chemical transport regulations, ensuring safety during transit to prevent any leakage or hazard. |
| Storage | 3 - Chloro - 1,2 - benzisothiazole 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 and air exposure, which could potentially lead to decomposition or reactivity. Ensure the storage area is clearly labeled for easy identification and to avoid accidental mixing with other chemicals. |
|
Does a single-component isothiazolinone derivative with a chlorine substituent at the 3-position extend in-can preservation beyond what methylisothiazolinone/benzisothiazolinone blends achieve in flat wall paints formulated without formaldehyde donors? In aqueous styrene-acrylic and pure acrylic latex architectural coatings, the preservative is typically post-added during the letdown stage after pigment dispersion has been completed and the millbase has been cooled below 40 °C. The active, supplied as a 20% aqueous dispersion, is dosed at 0.10–0.20% w/w relative to total batch weight through a peristaltic metering pump into a low-shear recirculation loop fitted with an in-line static mixer to avoid localised concentration spikes that can cause destabilisation of the associative thickener network. In-can challenge testing according to ASTM D2574-16 (Standard Test Method for Resistance of Emulsion Paints in the Container to Attack by Microorganisms) with mixed inocula including Pseudomonas aeruginosa ATCC 10145 and Enterobacter cloacae demonstrates zero viable colony counts after 7 days of incubation at 30 °C when the equilibrium pH is maintained between 8.0 and 8.8. The finished products—typically interior matt emulsion paints meeting GB/T 9756-2018 or EN 13300 class 2 scrub resistance—retain viscosity and odour neutrality through a 24-month shelf life without reliance on formaldehyde-releasing agents. Regulatory compliance aligns with EPA FIFRA Section 3 registration for non-food-use in-can preservatives, the EU BPR Product-Type 6 in-can preservation listing subject to Article 95 active substance supply chain obligations, and GB/T 35602-2017 limits on harmful substances in architectural coatings. Process audits on 15,000-litre stainless steel letdown tanks equipped with variable-frequency dispersers set to 400–500 rpm confirm that incorporation at the end of the thinning phase—after coalescents and defoamers but before final rheology modifiers—minimises air entrapment and preserves biocide integrity. When Concentrate Premixes Are Stored at pH > 9.2 Before DilutionMetalworking fluid concentrate manufacturers routinely hold semi-synthetic soluble oil premixes in 1,000-litre stainless steel day tanks at ambient plant temperatures that can exceed 35 °C in summer campaigns, creating a chemical boundary condition where the 3-chloro-1,2-benzisothiazole molecule undergoes nucleophilic ring-opening hydrolysis at rates that deviate sharply from the quasi-linear stability observed below pH 9.0. Plant log data extracted from a centralised coolant blending operation in the Ruhr region indicates that when a concentrate adjusted to pH 9.5 with monoethanolamine is held for 48 hours before dilution, active agent recovery by HPLC drops by 12–18%, and the corresponding minimum inhibitory concentration against Pseudomonas fluorescens drifts from 75 ppm to above 200 ppm. To maintain a processing window where half-life exceeds 30 days, the premix pH is buffered to 8.6–8.9 using a 30% boric acid-amine ester system and the fluid temperature at biocide injection is held strictly below 35 °C. The compound, as a 20% active dispersion, is added at 2.5–3.5% w/w into the concentrate under high-shear mixing at 3,000 rpm for a minimum of 5 minutes using a rotor-stator inline homogeniser, ensuring uniform wetting of the inverse emulsion droplets. End-use dilution with water of 15 °dH hardness yields a milky microemulsion cutting fluid protected against bacterial spoilage at sump pH levels of 9.0–9.3. Regulatory classification falls under EU BPR Product-Type 13 metalworking fluid preservatives, with exposure scenarios aligned to TRGS 611 water-miscible coolant limits and validated by the standard suspension kill-time method ASTM E2315-16. The table below contains representative laboratory kinetic challenge data generated on a single batch of semi-synthetic concentrate diluted to 5% in synthetic hard water, evaluated against Pseudomonas aeruginosa ATCC 9027 at an active concentration of 100 ppm.
Acrylic emulsion pressure-sensitive adhesives post-synthesised thermal initiator fragments—predominantly persulfate residues left at 800–1,200 ppm after the main polymerisation hold—consume electrophilic isothiazolinones through nucleophilic attack at the sulfur atom, a pathway that is readily overlooked in standard preservation protocols built around methylisothiazolinone migration behaviour. Batch records from a 5-tonne emulsion vessel running a butyl acrylate/2-ethylhexyl acrylate copolymer at 48% solids show that direct addition of the biocide immediately after thermal kill at 82 °C results in a 25% loss of active within 90 minutes, measured by UV-derivative spectroscopy at 275 nm. To circumvent this, the latex is cooled to 50 °C, a sodium metabisulfite redox quench is applied to reduce residual oxidiser to below 50 ppm, and the pH is adjusted to 7.5–8.0 with ammonia before injecting the preservative at 0.05–0.12% w/w of the 20% aqueous dispersion through a diaphragm dosing head into the sweep of a slow-running anchor agitator. Vacuum stripping to remove unreacted monomer is conducted afterward, drawing residual volatile organics without stripping the active biocide component. The resulting tackified films coated on 36-µm PET carriers pass 24-month microbial resistance verification under ISO 20773:2013 conditional ageing at 40 °C and 75% relative humidity. Finished articles—transparent packaging tapes and removable labels—comply with indirect food-contact adhesive migration limits set forth in FDA 21 CFR 175.105 and Council of Europe Resolution AP(89)1, where extractable isothiazolinone content below 10 µg/dm² of food contact surface remains the enforcement threshold in third-party auditing. Managing Residual Formaldehyde Scavenger Interactions During LetdownFormaldehyde-free interior wall paints marketed under the “Zero-Added Formaldehyde” certification schemes frequently incorporate carbamide or amino-alcohol scavenger packages that react not only with free formaldehyde but also with the electrophilic chlorine site on 3-chloro-1,2-benzisothiazole, forming adducts that exhibit negligible antimicrobial activity in subsequent ASTM D2574 challenge panels. Production runs on a 3,000-litre open-top disperser where an amino-formaldehyde scavenger had been added at the pigment grin d stage at 0.3% w/w showed complete preservative failure within 14 days of shelf storage when the isothiazolinone was co-incorporated during the letdown without a temporal separation step. The corrected sequential process requires the scavenger to be dispersed into the millbase before the letdown phase, a hold period of at least 30 minutes after scavenger addition for the free-formaldehyde condensation to plateau below 10 mg/kg (verified by an in-line acetylacetone colorimetric probe), and only then the biocide dosed at 0.15–0.25% w/w of the 20% active dispersion to compensate for the known 5–8% loss attributable to residual scavenger carryover in the bulk liquid. The latex paint, packaged in 20-litre HDPE pails with headspace nitrogen flushing, maintains a microbiological stability envelope defined by ISO 11930:2012 (single-inoculum preservation challenge) over a 36-month commercial shelf life. End products meeting the IKEA IOS-MAT-0066 formaldehyde emission class or AgBB scheme for indoor air quality rely on this sequenced addition to avoid the premature consumption of the active molecule, and the practice is anchored in the quality operating procedures of several tier-1 architectural coatings manufacturers serving the European DIY market. Post-fleshing brine curing of bovine hides destined for export as wet-blue intermediates operates in a narrow chemical envelope of pH 2.8–3.2 and sodium chloride saturation between 6–8°Bé, a hyperosmotic environment that severely limits the passive diffusion of conventional benzisothiazolinone-based dips while also screening out the ionised form of chlorinated isothiazolinones. Field bacteriology swabs taken from commercial tanning drums in the Arzignano tanning district show that a dosing regimen of 0.12–0.20% 3-chloro-1,2-benzisothiazole (as 20% active dispersion) on fleshed weight, applied via a spray lance into the drum after 60 minutes of acid-salt mechanical rotation, reduces halophilic colony-forming units in the float to below 10² CFU/mL after 16 hours of processing. The compound is added once the collagen fibre opening reaches the desired degree of turgor and the float temperature has stabilised at 22–25 °C, conditions under which the molecule remains stable for the 18–24 hours required for full brine penetration. Finished wet-blue stock produced by this protocol conforms to ZDHC MRSL Version 2.0 requirements for restricted biocide residues, and the preservative leaves no detectable dithiocarbamate or TCMTB (2-(thiocyanomethylthio)benzothiazole) markers that frequently cause consignment rejection under REACH Annex XVII entry 46a restrictions on certain compounds in leather articles. Standardised microbial challenge of the process float follows the principles of ASTM D4576-16 (Standard Test Method for Mold Growth Resistance of Blue Stock), with wet-blue specimens showing an absence of fungal mycelial growth after 28 days at 28 °C and 95% relative humidity. To Preserve Calcium Carbonate Slurries Intended for Coated Paper Production Without Brightness ReversionGround calcium carbonate slurries at 75% solids used as blade-coating pigments in woodfree paper grades are prone to biodeterioration by anaerobic sulfate-reducing bacteria during storage in 100-tonne stock tanks, where sedimentation zones create oxygen-depleted microenvironments. The biocide dispersion is metered at 0.15–0.30% w/w based on dry pigment mass into the recirculating loop of an inline rotor-stator mixer immediately downstream of the media mill classifying screen, ensuring uniform wetting of the ultrafine GCC particles with a particle size distribution d₅₀ < 2 µm. This placement avoids extended contact with the high-temperature mill exit stream (typically 70–75 °C) and eliminates the brightness loss observed when phenolic-type preservatives partially oxidise on the hot pigment surface. The treated slurry, processed into lightweight coated papers with a coat weight of 8–12 g/m² per side, satisfies the indirect food additive compositional requirements of FDA 21 CFR 176.170 (paper and paperboard in contact with aqueous and fatty foods) and the German Federal Institute for Risk Assessment BfR Recommendation XXXVI, provided the total migrated isothiazolinone content remains below applicable detection limits established by EN 645 cold-water extractable protocols. |
Competitive 3-Chloro-1,2-Benzisonthiazole prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please call us at +8615651039172 or mail to sales9@bouling-chem.com.
We will respond to you as soon as possible.
Tel: +8615651039172
Email: sales9@bouling-chem.com
Flexible payment, competitive price, premium service - Inquire now!
3-Chloro-1,2-benzisothiazole (CAS 7716-66-7) is supplied as a pale yellow crystalline solid at ambient temperature, with a molecular formula of C7H4ClNS and a molecular weight of 169.63 g mol−1. This compound serves as a versatile electrophilic building block for the construction of fused heterocycles, particularly in agrochemical and pharmaceutical research. Commercial presentations consist of 25 kg fibre drums with a low-density polyethylene liner, sealed under dry nitrogen. Typical bulk purity, determined by gas chromatography with flame ionisation detection (GC-FID) using an internal standard method validated against ISO 17025, exceeds 99.0% (area normalisation). The material liquefies above 28–32 °C and is therefore handled as a low-melting solid; molten product darkens upon prolonged heating above 50 °C, a behaviour attributed to the onset of thermal dehydrochlorination. A differential scanning calorimetry (DSC) trace obtained per ASTM E794 reveals a sharp melting endotherm with an onset at 29.1 °C and a decomposition exotherm commencing at 178 °C, establishing a narrow safe melt-processing window.
The most critical operational parameter for this benzisothiazole derivative is its rapid moisture uptake and subsequent hydrolysis to 3-hydroxy-1,2-benzisothiazole, a transformation that introduces an unreactive phenol function and renders the batch unsuitable for nucleophilic displacement chemistry. Karl Fischer titration carried out in accordance with ISO 760 on freshly opened containers typically returns a water content of ≤0.10 %. When exposed to a relative humidity of 60 % at 25 °C, the solid adsorbs atmospheric water at a rate of approximately 0.05 % h−1 over the first four hours, crossing the 0.30 % specification limit after 6–8 h. Beyond this point, the liberated hydrogen chloride catalyses further ring-opening degradation, and the batch must be reprocessed by vacuum distillation. Production-scale handling therefore requires a closed-conveyance strategy: the product is discharged from a ribbon blender—fitted with a 15 μm absolute rating cartridge vent filter and purged with nitrogen at 0.2 bar—directly into an intermediate bulk container that is blanketed with dry air having a dew point of −40 °C. In one campaign run on a 500 L glass-lined reactor, the filter-dryer discharge port became obstructed after a nitrogen-flow interruption lasting 12 min; the resulting hydrolysis shell on the wet cake required mechanical raking and led to a 4.2 % reduction in batch purity.
Storage below 2 °C has been observed to induce polymorphism, generating a metastable crystal form that liquefies at a depressed melting point of 23–25 °C. To avoid this, the manufacturer’s stability protocol mandates storage at 2–8 °C under inert gas, with re-qualification every 12 months by gas chromatography and ion chromatography for chloride content. Even brief contact with strong aqueous bases causes immediate discolouration and precipitation of an intractable tar; therefore, all process lines must be free of residual alkaline cleaning agents. The compound is incompatible with primary and secondary amines in undiluted form, as the amine-chloride interchange can proceed exothermically, with a temperature rise exceeding 30 °C min−1 in adiabatic calorimetry tests (Phi-TEC II, adiabatic mode, Phi factor 1.05).
The following table documents the release specifications that must be met prior to shipment, along with the corresponding test methods. These criteria have been harmonised across three manufacturing sites and are embedded in ISO 9001:2015 batch records.
| Parameter | Specification | Test Method |
|---|---|---|
| Purity (GC area %) | ≥99.0 | In-house GC-FID, 30 m DB-5 column, calibrated against certified reference material |
| Melting Point | 28.0–32.0 °C | ASTM E794 (DSC, onset temperature) |
| Water Content | ≤0.30 % (w/w) | ISO 760 (volumetric Karl Fischer) |
| Residual Chloride Ion | ≤50 mg kg−1 | Ion chromatography, conductivity detection, as Cl− |
| Appearance | Pale yellow, free-flowing crystalline solid | Visual inspection under D65 illuminant |
Within the 3-halogeno-1,2-benzisothiazole family, the chloride derivative occupies a median position between the more labile bromo and iodo analogues and the inert 3-fluoro congener, which shows negligible nucleophilic displacement activity under standard conditions. The chlorine atom is sufficiently electronegative—the Hammett substituent constant σp for the 3-chloro group is approximated as 0.66 based on 13C NMR chemical shift correlations—to activate the aromatic ring toward nucleophilic attack, yet the carbon‑chlorine bond dissociation energy (397 kJ mol−1) is high enough to confer room-temperature compatibility with solvents such as tetrahydrofuran, acetonitrile, and toluene. By contrast, 3-bromo-1,2-benzisothiazole, which exhibits a C–Br bond energy of 280 kJ mol−1, darkens visibly after 72 h of storage at 20 °C, even under nitrogen, as debromination slowly generates reactive benzisothiazole radicals. The iodo analogue decomposes within 24 h under identical conditions and is shipped only as a dilute solution at −20 °C, a logistical constraint that elevates supply-chain cost and precludes its use in many large-scale campaigns.
This stability gap permits the 3‑chloro compound to be inventoried for 12–18 months without re-purification, provided oxygen and moisture are excluded. The resulting supply reliability has made it the default electrophile for kilo-lab and pilot-plant routes to 3‑hydrazinyl‑, 3‑alkylthio‑, and 3‑alkoxy‑benzisothiazole intermediates. Reactivity can be fine-tuned through the choice of base: in the coupling with sodium thiophenolate in dimethylformamide, conversion after 2 h at 60 °C is 82 % when solid potassium carbonate (1.2 equiv) is employed, rising to 97 % upon substitution of caesium carbonate, consistent with an SNAr mechanism that is polarisable-anion assisted. No competing hydrolysis is detected as long as the reaction mixture is kept below 0.1 % water, a condition easily maintained with anhydrous solvent and inerted headspace.
| Property | 3-Chloro | 3-Bromo | 3-Iodo |
|---|---|---|---|
| Melting point (°C) | 29–31 | 46–48 | 72–74 |
| Boiling point (°C, 760 mmHg) | 263 | 285 | 310 (dec.) |
| Density (g cm−3, 20 °C) | 1.38 | 1.68 | 1.97 |
| Shelf life under N2 at 5 °C | 18 months | 6 months | <1 month |
| Relative rate (amine displacement, DMF, 25 °C) | 1 (reference) | ~5 | >50 (accompanied by tar formation) |
In contrast to the prominent 1,2‑benzisothiazol‑3‑one (BIT), which is widely deployed as an in‑can preservative and is classified under the EU Biocidal Products Regulation, 3‑chloro‑1,2‑benzisothiazole has no direct biocidal application; its value lies entirely in its function as a synthetic intermediate. Whereas BIT acts by oxidation of intracellular thiols, the 3‑chloro compound serves as a masked 3‑hydroxy group after hydrolysis or as a platform for creating carbon‑heteroatom bonds. The distinction is critical in downstream regulatory classification: the chlorinated intermediate is handled under REACH with an exposure scenario for chemical manufacture only, and it is not notified as a biocide under Regulation (EU) 528/2012. This simplifies material transfer documentation when moving between synthesis campaign sites.
Facilities that produce bis‑heterocyclic active ingredients for crop protection often stock both the 3‑chloro and the 3‑bromo variants. The selection matrix is governed less by absolute reactivity than by the stability of the subsequent coupling product. For instance, when a 3‑(pyrazol‑1‑yl)benzisothiazole library was investigated as a set of acaricide leads, the 3‑chloro precursor gave a more reproducible 10‑mmol‑scale output (93 ± 2 % HPLC purity, n = 5) than the bromo analogue (86 ± 8 %), owing to the lower incidence of ring‑opened by‑products. The chloride thus effectively buffers batch‑to‑batch variability, a factor that process development groups weight heavily when transferring a route from discovery to kilo‑lab scale.
Despite the strong preference for anhydrous media, some target molecules dictate the use of aqueous‑organic solvent mixtures, particularly when the nucleophile is an amino acid or a water‑soluble thiol. Here, the operational limit is defined by the pH profile of the reaction medium. At pH 7.0 and 25 °C, the half‑life of 3‑chloro‑1,2‑benzisothiazole in a 1:1 (v/v) tetrahydrofuran‑water system is 4.2 h; at pH 9.0 this collapses to 18 min. To extend the process window, the synthesis protocol introduces a buffering cocktail of 50 mM potassium phosphate (pH 6.8) and 10 % (v/v) dimethylacetamide, which retards hydrolysis sufficiently to permit 3 h of reaction time with ≥85 % conversion to the desired adduct. On a 200 L vessel equipped with a retreat‑curve impeller, the addition of the solid benzisothiazole must be portioned such that the local temperature never exceeds 15 °C; a single‑shot charge into an unbuffered solution resulted in a 7 °C temperature spike, a sudden drop in pH to 2.3 from the liberated HCl, and a batch yield of less than 10 %.
Process analytical technology (PAT) is employed to track the loss of the 3‑chloro group in real time. A ReactIR 15 probe, fitted with a diamond ATR element, monitors the C–Cl stretching band at 810 cm−1. When the absorbance ratio of the product carbonyl stretch (1635 cm−1) to the C–Cl band reaches the pre‑established endpoint value of 0.98, the batch is quenched by dilution with cold toluene, extracted, and the organic phase dried over molecular sieves (type 3A). This closed‑loop control has reduced the formation of the 3‑hydroxy impurity from a historic 8–12 % area (GC) to a steady ≤2.0 %. Such measures are essential when the downstream product is a pre‑clinical candidate that requires ≥99.5 % purity before formulation.
Distillative purification of the intermediate itself demands a short‑path wiped‑film evaporator with an internal condenser temperature of −5 °C and a jacket temperature not exceeding 120 °C. Residence time under vacuum (<1 mbar) is kept below 60 s to avoid polycondensation. Material that has been thermally stressed—for example, by storage near a heat exchanger—develops an amber tint and an elevated boiling point range, indicative of oligomer formation, and is diverted for waste‑solvent disposal rather than re‑distillation.
The environmental fate of 3‑chloro‑1,2‑benzisothiazole has been profiled in accordance with OECD 301B (CO2 evolution test). The substance reaches 28 % of the theoretical CO2 after 28 days, classifying it as not readily biodegradable. Consequently, all aqueous process effluents containing the compound are routed through an activated‑carbon adsorption bed prior to biotreatment, with breakthrough monitored by UV absorbance at 310 nm. The activated carbon is regenerated thermally at 500 °C under nitrogen, a practice documented in the site‑wide environmental permit.
