2-Amino-6-Bromobenzothiazole
|
HS Code |
715737 |
| Chemical Formula | C7H5BrN2S |
| Molecular Weight | 229.097 g/mol |
| Appearance | Solid (usually white to off - white powder) |
| Melting Point | 198 - 202 °C |
| Solubility In Water | Insoluble |
| Solubility In Organic Solvents | Soluble in some polar organic solvents like DMSO, DMF |
| Odor | Odorless or very faint odor |
| Stability | Stable under normal conditions, but may react with strong oxidizing agents |
As an accredited 2-Amino-6-Bromobenzothiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 250g of 2 - Amino - 6 - Bromobenzothiazole packaged in a sealed plastic bag. |
| Shipping | 2 - Amino - 6 - Bromobenzothiazole is shipped in sealed, corrosion - resistant containers. It's carefully packaged to prevent damage. Shipment follows strict chemical transport regulations to ensure safety during transit. |
| Storage | 2 - Amino - 6 - Bromobenzothiazole should be stored in a cool, dry place away from direct sunlight. Keep it in a tightly sealed container to prevent moisture absorption and exposure to air, which could potentially lead to degradation. Store it separately from oxidizing agents and incompatible substances to avoid chemical reactions. |
In disperse dye manufacture, 2-amino-6-bromobenzothiazole serves as the primary diazo component for C.I. Disperse Blue 148, a blue azo dyestuff yielding high tinctorial strength on polyester substrates processed by high-temperature exhaust dyeing or thermosol fixation. The diazotization step constitutes the production bottleneck: the heterocyclic amine is dissolved in warm 30% hydrochloric acid (2.5–3.0 molar equivalents), shock‑cooled under high‑shear agitation to form a fine crystalline suspension, and held at −2 °C to +2 °C inside a glass‑lined monobloc reactor equipped with an independent brine circulation chiller capable of delivering jacket fluid at ≤−15 °C. Aqueous sodium nitrite (1.02 molar equivalents) is metered below the liquid surface through a dip tube at a rate that keeps the bulk temperature ≤+4 °C. Temperature deviation above +6 °C, even for 60 seconds, initiates exothermic decomposition of the diazonium salt with rapid nitrogen evolution and formation of intractable tarry by‑products; in worst cases reported on production lines where brine supply was interrupted, the resulting over‑pressurisation triggered the rupture disc. For this reason redundant high‑temperature alarms, an emergency quench tank of pre‑frozen water‑ice slurry, and a fail‑safe shutdown interlock on the nitrite metering pump are standard engineering controls across contract manufacturing units in India and China that regularly handle this intermediate at 500–2000 kg batch scale.Coupling is carried out in a separate glass‑lined vessel containing the coupler N,N‑diethyl‑m‑toluidine dissolved in acetic acid and diluted with water to a concentration of approximately 0.15 mol/L. The diazo solution is added gradually over 90–120 minutes while maintaining pH at 3.5–4.5 by automatic dosing of 20 wt% sodium acetate, the setpoint chosen to balance coupling rate against premature precipitation of the monoazo product that would entrain unreacted coupler. Temperature is held at 8–12 °C throughout to suppress tar formation yet permit a sufficient reaction rate; below 5 °C the coupling becomes impractically slow, while above 15 °C the colour yield drops 8–12% because of diazo degradation competing with coupling. After three hours of stirring, the slurry is pumped to a recessed‑chamber filter press and the cake washed with deionised water at 40 °C until the filtrate conductivity falls below 50 µS/cm. Final drying in a rotary vacuum dryer at ≤70 °C and ≤50 mbar preserves crystallinity and prevents dye sintering that would increase particle size beyond the 0.5–2.0 µm range required for dispersion stability. Finished C.I. Disperse Blue 148 presscake or powder is standardised to 100% strength by blending with dispersing agents such as sodium lignosulfonate and tested for light fastness according to ISO 105-B02:2014 (typical rating 5–6 on polyester), wash fastness per ISO 105-C06 (4–5), sublimation fastness per ISO 105-Z01, and forbids banned arylamines under REACH Annex XVII Entry 43. The commercial grade also routinely carries OEKO-TEX Standard 100 Appendix 4 certification with total chlorophenol content ≤0.5 mg/kg and heavy metals below detection limits.
How Is the Bromo Substituent Exploited in Drug Discovery Chemical Libraries?Within medicinal chemistry programmes the 6‑bromobenzothiazole scaffold is utilised as a late‑stage functionalisation handle because the C–Br bond undergoes oxidative addition to palladium(0) catalysts cleanly and under conditions that tolerate the free 2‑amino group only when suitably protected. The typical workflow employed at contract research organisations begins with in‑situ Boc protection of the 2‑amino position using Boc anhydride (1.2 eq) in tetrahydrofuran with N,N‑diisopropylethylamine as base, yielding the N‑protected intermediate which is then coupled with arylboronic acids via Pd(dppf)Cl₂·CH₂Cl₂ (0.02 eq) and potassium carbonate in a degassed 1,4‑dioxane/water mixture at 85 °C for 12 hours. The bromine atom also participates in Buchwald‑Hartwig aminations using BrettPhos‑precatalyst systems and sodium tert‑butoxide, enabling incorporation of primary or secondary amines required for constructing kinase‑hinge binding motifs. Purity specifications for building‑block catalogues mirror early‑phase GMP requirements: assay by HPLC at 254 nm ≥ 99.5 area%, any single impurity ≤ 0.10%, water content by Karl Fischer titration ≤ 0.3%, and residual solvents such as dioxane ≤ 380 ppm when the material is packed under nitrogen in double‑sealed aluminium‑lined bags inside 25 kg UN‑approved fibre drums. Impurity profiling includes specific quantification of the parent debrominated 2‑aminobenzothiazole and the 2‑amino‑6,6’‑dibromobithiazole homocoupling side product, each controlled below 0.05% because of their structural alert potential under ICH M7; a staged‑limit approach based on maximum daily dose of the final active pharmaceutical ingredient often caps the purge factor at 1.5 µg/day for the dimer. The supply chain normally includes a statement of compliance with ICH Q7 and a heavy‑metal residue report showing Pd ≤ 10 ppm, Fe ≤ 20 ppm, measured by ICP‑MS after microwave digestion.Agricultural Benzothiazole Fungicide PrecursorThe 2‑amino‑6‑bromobenzothiazole backbone is acylated to produce N‑(6‑bromobenzothiazol‑2‑yl)amide fungicides active against Basidiomycete pathogens including Rhizoctonia solani and Sclerotinia sclerotiorum. In a representative kilo‑lab preparation, the starting amine is suspended in dichloromethane and treated with 1.05 eq of a substituted benzoyl chloride in the presence of 1.2 eq triethylamine at 0–5 °C; the suspension turns to a clear solution and then deposits the target amide within 30 minutes. After aqueous wash and phase separation, the organic layer is distilled and the residue recrystallised from ethanol to deliver a product with melting point 218–221 °C and purity ≥ 98% by quantitative HPLC. Any unreacted 2‑amino‑6‑bromobenzothiazole remaining above 0.15% must be removed because it acts as a phytotoxicity promotor when formulated into suspension concentrates. Agrochemical formulators disperse the technical active ingredient at 250 g/L through wet bead milling with a naphthalene sulfonate‑based dispersant in a horizontal bead mill at 2000 rpm until particle size D50 reaches 1.0–1.5 µm; monitoring follows CIPAC MT 161. All batches intended for OECD markets are certified against the relevant FAO specification covering storage stability at 54 °C for 14 days and wet‑sieving residue. Manufacturing plants are expected to manage bromide‑laden aqueous effluent, typically through activated carbon adsorption or advanced oxidation, to meet a discharge consent of adsorbable organically bound halogens (AOX) ≤ 1 mg/L as required under the EU Industrial Emissions Directive.When the Intermediate Enters Rubber Antidegradant SynthesisCondensation of 2‑amino‑6‑bromobenzothiazole with 4‑aminodiphenylamine (4‑ADPA) in boiling xylene under a slow nitrogen sweep generates N‑(6‑bromobenzothiazol‑2‑yl)‑N’‑phenyl‑p‑phenylenediamine, a brown viscous semi‑solid at room temperature that functions as a non‑staining antidegradant in natural rubber and styrene‑butadiene rubber compounds. The batch process is catalysed by p‑toluenesulfonic acid monohydrate at 0.5 wt% based on the amine charge and is driven by azeotropic water removal through a Dean‑Stark trap; completion is confirmed when water generation ceases and the free 4‑ADPA content drops below 0.2% by thin‑layer chromatography. After vacuum stripping of xylene at ≤100 °C and ≤10 mbar, the hot residue is flaked on a chilled belt flaker and packaged in 200 kg steel drums. Compounding trials on a two‑roll mill (friction ratio 1.2:1) incorporate the antidegradant at 1.5–2.0 phr into a carbon‑black‑filled NR/BR truck tread formulation alongside 1.0 phr of N‑cyclohexyl‑2‑benzothiazolesulfenamide (CBS) accelerator and sulfur. Moving‑die rheometer data acquired per ISO 6502:2023 at 150 °C show a minimal impact on scorch time ts2 (≤7% variation relative to the control). Aged tensile bars exposed to 100 °C forced‑air ovens for 72 hours according to ASTM D573‑04(2021) retain at least 82% of the original tensile strength and 74% of elongation at break. Migration behaviour tested by HPLC‑UV on a rubber‑to‑paint contact transfer specimen indicates that the bromine atom reduces migration loss by approximately 30% compared to the non‑halogenated analogue due to higher molecular weight and altered solubility parameter. Compliance with AfPS GS 2019:01 PAK for polycyclic aromatic hydrocarbons is maintained because the compound decomposes before reaching PAH‑formation temperatures and the antidegradant lot releases BaP at ≤0.5 mg/kg.Circulating cooling water systems containing admiralty brass or aluminium‑brass heat exchanger tubes rely on heterocyclic inhibitors to suppress pitting corrosion caused by chloride ions concentrating under fouling deposits. 2‑Amino‑6‑bromobenzothiazole at concentrations of 15–50 mg/L forms a persistent chemisorbed layer on Cu2O‑rich passive films, the bromine substituent raising the electron density on the thiazole nitrogen and improving adhesion strength relative to unsubstituted benzothiazole as measured by scanning electrochemical microscopy. Linear polarisation resistance (LPR) monitoring using two‑electrode probes installed in bypass racks yields corrosion rates consistently below 0.02 mm/year when the inhibitor residual is kept above 20 mg/L and the free chlorine residual from on‑site hypochlorite generation is held at ≤0.1 mg/L; values climb to 0.08 mm/year within 4 hours if the free chlorine exceeds 0.5 mg/L because the hypochlorite oxidises the chemisorbed film, converting the bromine into soluble hypobromite. Potentiodynamic polarisation tests executed in synthetic cooling water containing 585 mg/L CaCl2, 300 mg/L MgSO4, and 1100 mg/L NaCl at 45 °C under ASTM G5‑14(2021) with a scan rate of 0.167 mV/s reveal a shift of corrosion potential Ecorr from approximately −220 mV vs SCE (uninhibited) to −70 mV and a reduction of the corrosion current density icorr from 1.8 µA/cm² to 0.04 µA/cm², corresponding to an inhibition efficiency of 97.8%. The electrochemical data are validated by immersion tests run for 30 days per ASTM G31‑21 with duplicate CDA 443 specimens weighed to 0.1 mg precision after Clarke’s solution descaling. A synergistic booster effect is observed with 2‑mercaptobenzothiazole (MBT) at a 4:1 weight ratio, driving the corrosion rate below 0.010 mm/year even in the presence of 50 mg/L suspended solids.
Photochromic Spirooxazine Generation and Fatigue ResistanceCondensation of 2‑amino‑6‑bromobenzothiazole with a 2‑methyleneindoline derivative in refluxing anhydrous toluene catalysed by trimethylsilyl chloride yields a spiro[indoline‑2,3’‑[3H]naphtho[2,1‑b][1,4]oxazine] bearing the 6‑bromobenzothiazole moiety on the naphthoxazine ring, a photochromic dye that turns deep blue upon exposure to UV‑A radiation. The synthesis is conducted under rigorously dry nitrogen in a double‑jacketed reactor; water content must remain below 50 ppm as verified by Karl Fischer titration of the refluxing solvent, otherwise the indoline intermediate hydrolyses and the cyclisation yield drops below 50%. After cooling to 25 °C and filtration over a silica gel pad, the toluene is removed under reduced pressure and the residue crystallised from n‑heptane to afford a pale yellow powder with a melting point of 162–165 °C and HPLC purity exceeding 99.0%. When dissolved into a two‑component polyurethane lens monomer system comprising poly(hexamethylene carbonate) diol and dicyclohexylmethane‑4,4’‑diisocyanate at a concentration of 0.03–0.08 wt% and thermally cured for 20 hours at 120 °C, the resulting 1.8 mm thick plano lens reaches an activated luminous transmittance of ≤15% after 15 minutes of UV exposure (50 W/m² xenon‑filtered source) and fades to a half‑activation state within 22 seconds at 23 °C as measured by the photochromic fatigue protocol of ISO 8980‑3:2022. The bromine atom contributes a bathochromic shift of approximately 12 nm relative to the chloro analogue, placing the maximum absorption at 598–602 nm which aligns well with the photopic sensitivity curve. Fatigue resistance after 50,000 cycling exposures exhibits a degradation of less than 8% in the fully activated state, a threshold routinely verified by third‑party test laboratories. One documented processing incompatibility concerns cast acrylic (CR‑39) matrices: the photochromic dye reacts with the diisopropyl peroxydicarbonate initiator during polymerisation, leading to deactivation of the photochromic function and a permanent brown discolouration of the lens blank.Acid copper electroplating formulations for high‑aspect‑ratio PCB through‑hole metallization demand organic leveling agents that selectively suppress copper deposition at high‑current‑density peaks without retarding low‑current‑density via interiors. The quaternised derivative of 2‑amino‑6‑bromobenzothiazole synthesised by reaction with dimethyl sulfate (1.0 eq) in toluene at 60 °C for 6 hours, followed by phase separation and vacuum drying, delivers a quaternary ammonium‑type additive that is dosed at 15–45 mg/L into a standard acid copper sulphate bath containing 220 g/L CuSO4·5H2O, 55 g/L H2SO4, and 70 mg/L chloride ion. Hull cell panels plated in a 267 mL cell at 2 A for 5 minutes at 25 °C with continuous air agitation show a fully bright range extending from 0.4 A/dm² to 9.0 A/dm²; without the additive the bright range collapses to 1.0–3.5 A/dm². The synergistic requirement of chloride is absolute: when the chloride concentration falls below 50 mg/L, the deposit becomes hazy and rough even at the optimum current density, an effect traced to competitive adsorption of the quaternary benzothiazolium cation onto nascent copper crystallites. At concentrations above 60 mg/L of the quaternised additive, low‑current‑density areas develop a slight brownish film, limiting the upper working window. The electroplating bath with this additive is routinely monitored by cyclic voltammetric stripping (CVS) per the method outlined in IPC‑TM‑650 2.3.17 and the deposit ductility is verified by a 2×90° bend test on electroformed copper foil coupons according to ASTM B489‑85(2018). Spent bath treatment requires carbon batch treatment for 4 hours at 50 °C to remove accumulated organic breakdown products, after which the concentration of the active leveler can be replenished based on the area of the Hull cell bright plate. |
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| 6‑Substituent | CAS | Mw (g·mol⁻¹) | m.p. (°C) | Suzuki Coupling Relative Ratea | Typical Application Domain |
|---|---|---|---|---|---|
| —H | 136-95-8 | 150.20 | 127–130 | 1.0 (reference) | Rubber accelerators, unsubstituted azo dyes |
| —Cl | 95-24-9 | 184.65 | 199–203 | 4.2 | Pharmaceutical intermediates (kinase inhibitors) |
| —Br | 15864-32-1 | 229.10 | 216–219 | 12.8 | Fine chemicals, high‑temperature coupling, disperse dyes |
| —CH₃ | 2536-91-6 | 164.23 | 136–139 | —b | Melt‑processable polymer additives |
| Parameter | Specification | Method |
|---|---|---|
| Appearance | White to off‑white crystalline powder | Visual inspection vs. RAL 9003 standard |
| Assay (HPLC area%) | 98.0% minimum | USP <621>; C18, 254 nm |
| Melting point | 216–221 °C (dec.) | ASTM E324-21 |
| Water content | ≤0.5% | USP <921> Method Ia |
| Residue on ignition | ≤0.1% | USP <281> |
| Heavy metals (as Pb) | ≤10 ppm | USP <231> Method II |
| Single unknown impurity | ≤0.5% | USP <621> |
