3-Amino-5-Nitro-2,1-Benzisothiazole
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HS Code |
456411 |
| Chemical Formula | C7H5N3O2S |
| Appearance | yellow powder |
| Melting Point | 189 - 193 °C |
| Solubility In Water | poorly soluble |
| Solubility In Organic Solvents | soluble in some organic solvents like DMSO |
| Stability | stable under normal conditions, but may react with strong oxidizing agents |
As an accredited 3-Amino-5-Nitro-2,1-Benzisothiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram vial packaging for 3 - Amino - 5 - Nitro - 2,1 - Benzisothiazole chemical. |
| Shipping | 3 - Amino - 5 - nitro - 2,1 - benzisothiazole is shipped in accordance with strict chemical regulations. It is carefully packaged in suitable containers to prevent leakage, with proper labeling for safe and compliant transportation. |
| Storage | 3 - Amino - 5 - nitro - 2,1 - benzisothiazole should be stored in a cool, dry, well - ventilated area. Keep it away from heat sources, flames, and oxidizing agents. Store in a tightly sealed container to prevent moisture absorption and potential degradation. Separate from incompatible substances to avoid chemical reactions. This helps maintain its stability and safety during storage. |
In the commercial synthesis of heterocyclic disperse dyes for polyester and its blends with cellulosics, 3-amino-5-nitro-2,1-benzisothiazole is deployed exclusively as the electron-deficient diazo component. The industrial diazotization is executed at -8 °C to -2 °C in 85–92 % sulfuric acid or a mixed phosphoric–acetic acid medium using a stoichiometric slight excess of nitrosylsulfuric acid, maintaining a reaction time of 60–90 minutes until a negative starch–iodide test is sustained for 10 minutes. The resulting diazonium solution is then coupled onto N-cyanoethyl-N-(acetoxyethyl)aniline or N,N-bis(acetoxyethyl)-m-toluidine at 0–4 °C, pH controlled between 1.2–1.8 by the addition of sodium acetate, yielding in >88 % crude yield a blue azo chromophore with λmax in dimethylformamide at 608–618 nm. After drowning, filtration on a plate-and-frame press, and washing to conductivity <500 µS/cm, the presscake is reslurried with 1.5–2.0 parts (by dry weight) of a sodium lignosulfonate–naphthalene sulfonate condensate dispersant blend and sand-milled in a horizontal bead mill (e.g., a Bühler PML-2 with 0.4–0.6 mm yttria-stabilized zirconia beads) until the mean particle size reaches 0.8–1.2 µm by laser diffraction (ISO 13320:2020). The liquid dispersion is spray-dried at an inlet temperature of 180–200 °C to produce a granular form. A representative CI constitution, C.I. Disperse Blue 174 or analogs, is employed in exhaust dyeing of polyethylene terephthalate at 130 °C for 45–60 min in a high-temperature jet dyeing machine with a liquor ratio of 1:8–1:12 and a pH 4.5–5.0 (acetic acid–sodium acetate buffer), delivering a deep navy-blue shade. Fastness performance tested to ISO 105-C06:C2S washing shows shade change 4–5 and staining 4 on multifiber; light fastness under ISO 105-B02:2014 (xenon arc, 42 W/m2 at 420 nm) reaches 6–7 at 1/1 standard depth; sublimation fastness assessed by ISO 105-P01:1993 at 180 °C/30 s gives a 4 rating. During thermofixation at 210 °C for 60 s, a shade shift of 0.8–1.2 CIELAB ΔE units is recorded, which is within the stipulated shade continuity tolerance for continuous dyeing ranges. A comparative dataset for four coupling component variants is tabulated below.
What Solvent Dye Applications Justify the Use of a Nitro-Substituted Benzisothiazole Scaffold?The 3-amino-5-nitro-2,1-benzisothiazole chromogen, when coupled onto lipophilic acetanilide or tetrahydroquinoline promizers, yields transparent solvent dyes with solubility in toluene at 25 °C exceeding 80 g/L and in methyl ethyl ketone above 45 g/L. These dyes are integrated into gravure printing inks for polyethylene terephthalate packaging films, where migration resistance is critical. A typical letdown formulation consists of 1.5–2.5 wt% of the solvent dye (dry basis), 10–12 % nitrocellulose binder (1/4-second grade, DIN 53179), 4–6 % ketone-formaldehyde resin, and a plasticizer blend of dibutyl phthalate and epoxidized soybean oil to a total plasticizer content of 8–10 %, with the balance made up of ethyl acetate/isopropanol (60:40 v/v) to bring the viscosity to 22–28 s on a DIN 4 mm flow cup at 23 °C. High-speed rotogravure printing at 150–250 m/min on corona-treated polyester (surface energy ≥48 mN/m) delivers an optical density of 1.8–2.2 at a film thickness of 2–4 µm dry. The critical failure mode is long-term interlayer dye migration into the food simulant under chilled or ambient conditions; specific migration limits (SML) are probed per EU Regulation 10/2011, Annex V, with simulant B (3 % acetic acid) and simulant D2 (vegetable oil) using LC-MS/MS quantification. Values below 10 µg/dm² are routinely achieved when the dye is retained by the nitrocellulose matrix at an addition level not exceeding 2.0 wt%. When compounded into styrenic thermoplastics, the dye resists migration to a classification of A (no migration) under ISO 15701:2022 at 0.05–0.2 % pigmentation mass, with heat stability evaluated by thermogravimetric analysis showing 1 % mass loss at 332 °C in nitrogen. For injection-molded polycarbonate articles, a pre-drying step at 120 °C for 4 h is mandatory to prevent hydrolytic decomposition, and processing temperatures must remain below 300 °C to avoid dye degradation resulting in a hue shift toward yellow. Toxicity screening for heavy-metal content according to EN 71-3:2019 demonstrates arsenic <5 mg/kg, cadmium <1 mg/kg, and lead <5 mg/kg in the final compounded colorant.When a Diamine Curing Agent Outperforms 4,4′-MDA — Catalytic Hydrogenation to 3,5-Diaminobenzisothiazole for Epoxy SystemsSelective reduction of 3-amino-5-nitro-2,1-benzisothiazole to the corresponding 3,5-diaminobenzisothiazole is carried out in anhydrous tetrahydrofuran or methanol with 3–5 wt% (on feed basis) of a 5 % palladium-on-carbon catalyst (dry basis, water content <50 % by Karl Fischer) under a hydrogen pressure of 2.5–3.0 MPa at 65–75 °C. After hydrogen uptake ceases, the catalyst is filtered warm through a 0.5 µm polytetrafluoroethylene membrane, the solvent is stripped under reduced pressure, and the diamine is isolated as a light-beige crystalline solid with a purity >99.2 % by HPLC (area % at 254 nm) and a melting point of 148–150 °C. This curing agent is blended with a bisphenol A diglycidyl ether resin (epoxide equivalent weight 188–192 g/eq) at an amine:epoxide stoichiometric ratio of 0.95:1.00 to avoid exothermic overshoot. The blend is degassed under vacuum 50 mbar for the minute-scale duration needed to reach a bubble-free meniscus before curing in a convection oven using a ramped cycle: 80 °C for 1 h, 120 °C for 2 h, post-cure 180 °C for 1 h. The resulting thermoset exhibits a glass transition temperature (Tg) of 207 °C by dynamic mechanical analysis (DMA, ASTM D7028-07, 1 Hz, 3 °C/min) and a coefficient of thermal expansion below Tg of 48 ppm/°C by thermomechanical analysis. Flexural strength tested in accordance with ASTM D790-17 at 23 °C reaches 142 MPa with a modulus of 3.9 GPa, while the onset of thermal decomposition by thermogravimetry (ASTM E1131) in nitrogen at 10 °C/min is recorded at 352 °C. In comparative fire-performance assessments, a formulation loaded with 12 phr of ammonium polyphosphate (Exolit AP 423) achieves a V-0 rating at 1.6 mm thickness under UL 94, with a limiting oxygen index (LOI, ASTM D2863) of 34 %. The diamine is incompatible with standard benzoxazine resins below 80 °C due to a competing ring-opening reaction that causes premature gelation, making it exclusively suited to epoxy formulations processed above ambient temperature.Direct conjugation of 3-amino-5-nitro-2,1-benzisothiazole to a vinyl sulfone reactive anchor via a triazinyl bridging group yields a high-exhaustion reactive blue dye for cellulosic fibers. The intermediate is first condensed at 0–5 °C with 1.0 molar equivalent of 2,4,6-trichloro-s-triazine in acetone–water, maintaining pH 5.5–6.0 through the gradual addition of 10 % sodium carbonate. The condensation product is coupled onto p-aminophenyl-b-hydroxyethyl sulfone sulfate ester under the same pH and temperature regime, after which the sulfatoethyl sulfone precursor is stable in dry form. During exhaust application in a long-liquor jet dyeing machine at a liquor ratio of 1:10, 1.5 % owf of the reactive dye is added to a neutral bath; sodium sulfate is introduced at 40 g/L in two divided portions to promote substantivity, followed by the addition of 15 g/L sodium carbonate over 30 min to fix the dye at 60 °C for 90 min. The terminal wash-off sequence comprises a hot rinse at 90 °C with 1 g/L anionic soaping agent (e.g., a fatty alcohol polyglycol ether sulfate) for 15 min and two warm rinses. Color yield, measured as K/S at λmax 610 nm on mercerized cotton, falls in the range 18–22; light fastness ISO 105-B02 is 5–6 at standard depth; wet rubbing fastness ISO 105-X12 is 3–4 dry and 3 wet without an aftertreatment fixative, a characteristic that mandates the use of a cationic formaldehyde-free fixer for end-uses requiring 4 in wet rubs.Photoacid Generation and UV-Crosslinking Formulations as a Latent CatalystIn cationically curable coating and printing plate compositions, 3-amino-5-nitro-2,1-benzisothiazole is converted into a latent photoacid generator (PAG) by N-alkylation with a fluorinated benzyl halide to form a nitrobenzisothiazolium salt that photolyzes upon exposure to broadband UV-A radiation between 350–420 nm. The PAG is dissolved in a formulated epoxidized linseed oil oligomer mixed with 3–5 wt% of an oxetane reactive diluent (3-ethyl-3-hydroxymethyloxetane) to reduce the viscosity to 800–1200 mPa·s at 25 °C. Under a focused mercury-xenon lamp delivering 2.5 J/cm² in the UVA band measured with an EIT PowerMAP radiometer, the coating cures to a tack-free surface within 8–12 s, developing a solvent-resistant network (MEK double rubs >200 per ASTM D5402). The critical pitfall is the storage stability of the liquid formulation: at temperatures above 35 °C the PAG slowly undergoes thermal elimination, dropping the formulation pot life from 48 h to less than 6 h. Therefore, dual-cartridge mixing systems or refrigerated transport at 4–8 °C is recommended for trade distribution. The cured film shows a cross-hatch adhesion of class 0 on cold-rolled steel panels under ISO 2409:2020 after 24 h of water immersion, and a pendulum hardness (Koenig) of 160–175 s (ISO 1522:2022).Fungicidal and insecticidal lead structures built on the benzisothiazole scaffold often incorporate the 3-amino-5-nitro-2,1-benzisothiazole core as a functionalized pharmacophore. An established semisynthetic route involves condensation of the amine with chloroacetyl chloride in dry dichloromethane in the presence of triethylamine at 0–5 °C to form the corresponding α-chloroacetamide, which is subsequently reacted with sodium sulfide nonahydrate and sulfur in refluxing ethanol to generate a 2-mercaptobenzisothiazole derivative. In vitro efficacy screening for such sulfenamide congeners against Rhizoctonia solani (agar dilution method at 20 µg/mL, incubation 72 h at 25 °C) indicates >85 % mycelial growth inhibition, though published data for the specific isomeric nitro-substitution pattern of this intermediate is limited and structure–activity relationships must be interpreted cautiously; the nitro group positioned at C-5 frequently correlates with a sharp increase in acute fish toxicity (LC50, 96 h, Danio rerio <10 mg/L in regulatory testing per OECD Test Guideline 203), which restricts commercialization to seed-treatment or non-aqueous material preservation applications where release into surface water can be technically avoided.Where charge-transport properties are targeted, the parent heterocycle is elaborated into fused bis-benzisothiazole oligomers by a palladium-catalyzed Buchwald–Hartwig amination of 3-amino-5-nitro-2,1-benzisothiazole with brominated comonomers, followed by partial reduction of the nitro group to the hydroxylamine and oxidative cyclization. This yields an electron-deficient ladder-type backbone exhibiting an electron affinity of 2.8–3.1 eV by cyclic voltammetry (Ag/AgCl reference, ferrocene internal standard, scan rate 50 mV/s, 0.1 M tetrabutylammonium hexafluorophosphate in acetonitrile). The semiconducting oligomer, when applied as a thin-film electron transport layer in a organic field-effect transistor test structure, yields an electron mobility of 2.3×10⁻³ cm²/V·s under ambient atmosphere on octadecyltrichlorosilane-treated SiO2 dielectrics. The limitation for large-area coating is the oligomer’s low solubility in non-halogenated solvents (<2 mg/mL in anisole), which necessitates the use of 1,2-dichlorobenzene and a heated slot-die coater maintained at 70 °C to form a continuous film.
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| Parameter | Specification | Test Method |
|---|---|---|
| Appearance | Yellow to orange crystalline powder | Visual inspection |
| Purity (HPLC, area‑%) | ≥ 98.5% | In‑house RP‑HPLC, λ = 254 nm |
| 6‑Nitro isomer content | ≤ 0.8% | HPLC, external standard |
| Melting range (decomposition) | 171–175 °C | ASTM E324‑16, capillary |
| Loss on drying (105 °C, 2 h) | ≤ 0.5% | ISO 787‑2:2025 |
| Sulfated ash | ≤ 0.2% | ISO 3451‑1:2019 |
| Solubility in ethanol (25 °C) | > 20 g·L⁻¹ | Gravimetric |
| Isomer | CAS Registry Number | Melting Range (°C) | Relative Retention Time (HPLC) | Solubility in EtOH (25 °C, g·L⁻¹) |
|---|---|---|---|---|
| 3‑Amino‑5‑nitro‑2,1‑benzisothiazole (target) | 84387‑89‑3 | 171–175 | 1.00 | 22 |
| 3‑Amino‑6‑nitro‑2,1‑benzisothiazole | 84387‑90‑6 (provisional) | 155–158 | 0.88 | 28 |
| 3‑Amino‑7‑nitro‑2,1‑benzisothiazole | Not registered | 142–146 | 0.75 | 34 |
