2-(2-Hydroxy-4-Methoxyphenyl)Benzothiazole
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HS Code |
149977 |
| Chemical Formula | C14H11NO3S |
| Molar Mass | 273.31 g/mol |
| Appearance | Yellow - white solid |
| Solubility In Water | Poorly soluble |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, acetone |
| Melting Point | 150 - 152 °C |
| Uv Absorbing Property | Absorbs ultraviolet light in the range relevant for sunscreen applications |
| Thermal Stability | Moderate thermal stability up to certain temperatures |
| Function | Used as a UV absorber in sunscreens and polymers |
| Chemical Structure Feature | Contains a benzothiazole ring and a hydroxy - methoxyphenyl group |
As an accredited 2-(2-Hydroxy-4-Methoxyphenyl)Benzothiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram bottle packaging for 2-(2 - Hydroxy - 4 - Methoxyphenyl)Benzothiazole. |
| Shipping | 2 - (2 - Hydroxy - 4 - Methoxyphenyl)Benzothiazole is shipped in well - sealed containers, following strict chemical transport regulations. Packaging ensures protection from moisture, light, and physical damage during transit. |
| Storage | 2-(2 - Hydroxy - 4 - Methoxyphenyl)Benzothiazole should be stored in a cool, dry place away from direct sunlight. Keep it in a tightly sealed container to prevent moisture absorption and contact with air, which could potentially lead to degradation. Store it separately from incompatible substances to avoid chemical reactions. Suitable storage temperature is typically between 2 - 8 °C for long - term stability. |
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In calendered PVC films formulated for waterproofing membranes and tensile architecture enclosures, the incorporation of 2-(2-hydroxy-4-methoxyphenyl)benzothiazole addresses the photoinitiated dehydrochlorination chain reaction responsible for early-stage yellowing and embrittlement observed after as few as 600–800 h of ISO 4892-2:2013 xenon arc exposure. The compound is introduced at 0.2–0.4 phr relative to suspension-grade PVC resin (K-value 65–70) into the hot-cold mixing cycle of a turbomixer prior to gelation on a four-roll L-type calender operating with roll surface temperatures of 178–192°C and friction ratios of 1:1.15 on the final embossing roll. Processors must compensate for the stabilizer’s partial solubility in phthalate and trimellitate plasticizers, which can increase the critical dose required for surface weatherability by up to 35% when diisononyl phthalate levels exceed 45 phr; premixing the UV absorber at 60°C with the plasticizer fraction before dry-blending minimizes agglomerate formation detectable as gel specks in finished films thinner than 200 µm. Compliance with EN 13956:2013 for flexible sheets for waterproofing mandates retention of ≥80% of initial tensile strength after 5000 h UV aging, a threshold achievable only when the benzothiazole stabilizer is combined with 0.1–0.2 phr of a high-molecular-weight HALS. Finished goods range from single-ply roofing membranes with polyester reinforcement scrim to biogas digester covers requiring ASTM D3106 abrasion resistance validation. Why Coextruded Rigid PVC Profiles Demand Non-Volatile Benzothiazole UV FiltersWhen formulating a weatherable coextruded capstock for unplasticized PVC profiles, the selection of a UV absorber pivots on migration resistance during the repeated thermal cycling of a conical twin-screw extruder (L/D 26–28, counter-rotating, screw diameter 54–65 mm) operating at melt temperatures of 188–203°C in the metering zone. 2-(2-Hydroxy-4-methoxyphenyl)benzothiazole at 0.3–0.5 wt% in the capstock compound demonstrates a vapour pressure below 1 × 10⁻⁶ Pa at 200°C, which prevents die-lip build-up and stabilizer sublimation onto calibrator surfaces—a recurring failure mode with lower-molecular-weight UV absorbers that causes surface defects and gloss variation across 6 m profile lengths. The capstock layer, extruded at a thickness of 180–250 µm through a slot die positioned 15–25 mm upstream of the calibrator inlet, must maintain uniform optical density; batch-to-batch variations in stabilizer particle size distribution above D₉₀ 50 µm have been documented to create micro-voids visible under 50× magnification after 3000 h natural weathering in Florida test fences. Processing boundaries are sharply defined: barrel zone temperatures exceeding 205°C in the presence of residual moisture above 0.08 wt% initiate heterocyclic ring-opening that shifts the absorption maximum from 345 nm to 380 nm, producing a noticeable yellow chromophore in white and pastel formulations. Purging with rigid PVC containing 5 wt% calcium carbonate before shutdown is standard practice to remove degraded stabilizer residues from dead spots in the coextrusion block. Adherence to EN 12608-1:2020 for unplasticized PVC profiles requires the capstock to maintain impact resistance (unnotched Charpy ≥20 kJ/m² at 23°C) after 6000 h artificial weathering; this is routinely achieved when the benzothiazole compound is incorporated via a masterbatch produced on a co-rotating twin-screw extruder (L/D 44) with a dispersive screw geometry. Final profile types include tilt-and-turn window frames, sliding door sashes, and fascia boards exposed to UV irradiance levels exceeding 120 kLy/y in subtropical installations. For styrenic block copolymer-based hot-melt pressure-sensitive adhesives employed in optical film lamination and anti-scratch surface protection tapes, protection of the exposed adhesive edge against UV-induced chain scission is achieved by pre-mixing 0.05–0.1 wt% of the benzothiazole compound into a molten styrene-isoprene-styrene stream at 155–165°C prior to slot-die coating onto a 23 µm polyethylene terephthalate carrier. The stabilizer level remains intentionally low to avoid migration into the adhesive interface layer, which would depress the 180° peel adhesion measured per ASTM D3330 Method A by more than 15%. This constitutes the shallowest addition profile among all commercial applications and requires no modification of the hot-melt coating line’s gear pump rpm settings. Polyurethane Coating Photooxidative Resistance and Aromatic Isocyanate InteractionsIn 2K aromatic and aliphatic polyurethane coatings exposed to QUV-B radiation according to ASTM G154 Cycle 2 (313 nm, 0.71 W/m², 60°C condensation), the benzothiazole absorber is pre-dissolved at 0.5–1.0 wt%—calculated on binder solids—into xylene-butyl acetate blends before combining with the polyisocyanate hardener. The hydroxyl group at the ortho position participates in intramolecular proton transfer, achieving a molar extinction coefficient ε of approximately 16,000 L·mol⁻¹·cm⁻¹ at 340 nm, which effectively shields the aromatic polyisocyanate crosslink sites from photon-induced quinoid formation that manifests as catastrophic yellowing at Δb > 4.5 within 1200 h. A limitation encountered during forced-air drying at 80°C involves the compound’s partial extraction into the air-water interface of waterborne polyurethane dispersions, reducing the effective concentration in the cured film by 30–40%; formulators compensate by introducing the stabilizer as an aromatic polyester polyol pre-adduct, a step that requires additional reactor time of 90 min at 100°C under nitrogen. High-gloss (≥90 GU at 60°) industrial topcoats formulated per ISO 16474-3:2013 cycle A demonstrate a delta E < 2.0 after 2000 h when the thickness of the clearcoat layer is maintained at 45–55 µm, a condition necessitating spray gun atomization pressure calibration within ±0.2 bar. End-use articles include factory-applied coil coatings for metal cladding, polyurea truck bed liners, and pigmented maintenance systems for offshore platform structural steel where the NORSOK M-501 Edition 7 prequalification demands visual surface integrity after 4200 h cyclic UV-condensation testing. SBS-modified bitumen waterproofing membranes illustrate a dual-degradation environment—thermal oxidation during 160–190°C high-shear mixing in a vertical plough-blade mixer and subsequent UV surface embrittlement on exposed roofing sections. 2-(2-Hydroxy-4-methoxyphenyl)benzothiazole at 0.2–0.5 wt% relative to the SBS phase is introduced after the bitumen oxidation blowing stage and before the addition of filler (25–30% calcium carbonate). The dispersion quality is monitored by measuring the absorbance ratio at 345 nm in microtome sections (50 µm), with a relative standard deviation exceeding 12% indicating inhomogeneity that correlates to premature microcracking at lap joints after 800 cycles of EN 13707:2013 Annex D dynamic heat-rain aging. In torch-applied systems, overheating the membrane during installation to >250°C can decompose the stabilizer instantaneously, a risk mitigated by mandating that applicators maintain the propane torch flame distance at 150–200 mm from the membrane surface. The stabilized product satisfies the cold-temperature flexibility requirement (-15°C mandrel bend, 25 mm radius) of ASTM D6164 Type 1 datasets even after 2500 h of ASTM G154 Cycle 1. If a Benzothiazole UV Absorber Is Introduced During Unsaturated Polyester Gel Coat CompoundingGel coat formulations based on orthophthalic or isophthalic unsaturated polyester resins require UV stabilization that does not interfere with the cobalt octoate-accelerated methyl ethyl ketone peroxide cure mechanism. Laboratory calorimetry data obtained under DIN 16945-2 indicates that the addition of 0.15–0.3 wt% of the benzothiazole compound retards the peak exotherm time by 2–4 min when the promoter concentration is held at 0.3 phr of 6% cobalt metal content, a shift that necessitates a concomitant increase in MEKP dosage from 1.5 phr to 1.8 phr to achieve a 25 min demould time in open mold spray-up of yacht hulls. The particle size of the UV absorber must be reduced to D₉₀ < 15 µm by pre-dispersing in styrene monomer using a toothed disc disperser at 3000 rpm, because larger agglomerates act as stress concentrators that reduce the Barcol hardness of the cured gel coat by 5–8 units. Outdoor exposure under ISO 4892-2:2013 cycle 6 conditions demonstrates that gel coats protected with this stabilizer sequence retain 80% of their initial 60° gloss after 3000 h, while unstabilized reference panels dip below 20% gloss within 800 h. Finished products encompass cultured marble vanity tops meeting ANSI Z124.1, shower stalls subjected to ASTM D256 Charpy impact after thermal cycling, and chemically resistant storage tank linings exposed to dilute alkali splashes per ISO 175.
A narrow application width that nonetheless demands exacting dispersion control is found in transparent polycarbonate/acrylonitrile-butadiene-styrene blends injection-molded into exterior automotive pillar trims. The additivation rate of 0.08–0.12 wt% is metered via a gravimetric side feeder into a 35 mm co-rotating twin-screw compounder (L/D 40) with downstream vacuum venting at -0.8 bar. Because of the benzothiazole’s limited solubility in the polycarbonate matrix, barrel zone profiling must delay its introduction to the fifth zone where the melt temperature has reached 260°C; premature addition results in striation patterns on the Class-A surface after nickel-plated mold thermal cycling. The stabilized resin must pass the SAE J1885 (xenon arc) interior trim colorfastness test with ΔE ≤ 3.0 after 1000 kJ/m². Finished parts featuring this stabilizer chemistry include B-pillar appliqués and sunroof wind deflector frames that face multidirectional UV ingress through glazing.
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The heterocyclic ultraviolet absorber 2-(2-Hydroxy-4-methoxyphenyl)benzothiazole — supplied as UVAsorb BT‑4M with molecular formula C₁₄H₁₁NO₂S and molecular weight 257.3 g/mol — delivers primary photoprotection through an excited-state intramolecular proton transfer (ESIPT) cycle that dissipates UV‑A energy as harmless thermal vibration before photochemical degradation can initiate. The methoxy group at the 4‑position shifts the absorption maximum into the 340–355 nm window, providing stronger overlap with the highest‑energy terrestrial UV flux while retaining sufficient solubility in styrenic, acrylic, and polycarbonate matrices for homogeneous incorporation at loadings below 1.0 wt%. Unlike simple benzophenone derivatives that rely on intermolecular hydrogen bonding and often release singlet oxygen during relaxation, the benzothiazole core’s rigid planar geometry suppresses parasitic triplet formation and maintains extinction coefficients above 19,500 L·mol⁻¹·cm⁻¹ (measured in dichloromethane at 25 °C, 0.01 g/L).
| Property | Specification | Test Method |
|---|---|---|
| Appearance | Pale‑yellow crystalline powder, free‑flowing | Visual / ISO 18451‑1:2018 |
| Melting range (onset) | 141–145 °C | DSC 10 °C/min under N₂, ASTM E967‑18 |
| Purity (HPLC, area%) | ≥ 98.5 % | In‑house method, C18 column, CH₃CN/H₂O |
| Loss on drying (105 °C, 2 h) | ≤ 0.5 % | ASTM D280‑01(2019) |
| Ash residue (800 °C) | ≤ 0.1 % | ASTM D5630‑13 |
| Absorbance at λmax (0.01 g/L, CH₂Cl₂) | > 1.90 A (10 mm path) | UV‑Vis spectroscopy |
| Particle size D50 (laser diffraction) | 8–14 μm | ISO 13320:2020 |
In gelcoat applications for marine laminates, the absorber is dissolved in unsaturated polyester resin prior to initiator addition. A loading of 0.3–0.5 wt% on total resin arrests surface yellowing and micro‑crack propagation through 1 500 hours of xenon‑arc exposure per ASTM G155 Cycle 1. Because the molecule exhibits no antagonism with cobalt- or amine-based promoters at these concentrations, post‑cure adhesion to glass‑reinforced backings remains above 4.5 MPa (lap shear, ASTM D3163‑01).
The 4‑methoxy substituent strengthens the intramolecular hydrogen bond between the phenolic −OH donor and the benzothiazole nitrogen acceptor, lowering the effective pKa* of the excited state and accelerating the ESIPT rate constant to > 10¹² s⁻¹. Compared with the parent 2‑(2‑hydroxyphenyl)benzothiazole, the methoxy‑derived red‑shift of 12–15 nm pushes the λmax from 336 nm to 348–350 nm, overlapping the UV‑A tail of terrestrial sunlight more completely. In poly(methyl methacrylate) films exposed to filtered xenon radiation (cut‑on 295 nm), the enthalpy‑neutral ESIPT loop reduces surface radical density by 78 % relative to an equimolar loading of 2‑hydroxy‑4‑methoxybenzophenone after 800 h of accelerated weathering (EPR spin‑trapping with DMPO). The absence of a triplet‑populated pathway also minimizes photo‑induced discoloration when the stabilizer is co‑formulated with hindered amine light stabilizers of the tetramethylpiperidine class.
Incorporation into polypropylene multifilament yarn intended for outdoor geotextiles typically proceeds via a 15–20 wt% additive masterbatch in a polypropylene homopolymer carrier (melt flow index 25 g/10 min, 230 °C/2.16 kg, ISO 1133‑1:2022). Let‑down at 0.15–0.25 wt% active in the final yarn preserves tenacity above 5.5 cN/dtex after 12 months of Florida‑exposed field aging (samples mounted unbacked at 45° south). Migration is controlled by the molecular volume: extraction in 95 % ethanol at 25 °C for 2 h (ASTM F2617‑20) consistently releases <0.08 % of the incorporated amount.
Compounding of UVAsorb BT‑4M into rigid PVC profiles for window lineals demands strict control of stabilizer chemistry. In formulations based on calcium‑zinc soaps and epoxidized soybean oil, a critical threshold emerges at 0.35 wt%: beyond this addition level, the methoxy oxygen can transiently coordinate zinc ions during shear, generating a chromophore that shifts the yellowness index from 2.1 to 4.7 (ASTM E313‑20) after two extrusion passes through a 25:1 L/D counter‑rotating twin‑screw extruder with barrel temperatures 160–180 °C and die temperature 190 °C. Capillary rheometry at 190 °C and a shear rate of 100 s⁻¹ records a 12–15 % drop in apparent viscosity upon loading to 0.30 wt%, an effect attributable to disruption of particulate gel networks rather than true plasticization. Consequently, screw torque must be monitored and barrel cooling resets applied when melt pressure exceeds 180 bar. Pre‑drying the absorber at 60 °C for 4 h (dew‑point ‑40 °C) is mandatory if storage relative humidity has exceeded 60 %, otherwise steam hydrolysis at the methoxy site produces phenolic breakdown products that accelerate dehydrochlorination. The use of methyltin mercaptide heat stabilizers is contraindicated: even trace residual mercaptan complexes yield an immediate pink discoloration, and no processing window narrower than ±3 °C has been identified that avoids it.
Polycarbonate sheet co‑extrusion imposes 280–310 °C on the cap‑layer melt, placing severe demands on absorber volatility. Thermogravimetric analysis at 10 °C/min under nitrogen shows 5 % mass loss at 235 °C for UVAsorb BT‑4M; however, dwell‑time‑weighted sublimation tests on a 300 µm cap‑layer processed at 295 °C reveal 2.3 % of the initial charge condensing on die lips over an 8 h run. This threshold lies within an operationally acceptable range if the die‑lip temperature is held 5–8 °C above the air dew‑point and a continuous polished‑lip wipe cycle ≤ 15 min is maintained. To suppress melt‑phase transesterification, the absorber is co‑fed alongside 0.05 wt% of a hydrolytically stable aryl phosphite processing stabilizer. In this configuration, 1 200 h of xenon‑arc exposure (ISO 4892‑2:2013, method A) on 4 mm sheets yields a Yellowness Index increase of <1.5 units and fracture elongation retention above 82 % (ASTM D638‑14, type V specimens).
| Metric | 2‑(2‑Hydroxy‑4‑methoxyphenyl)benzothiazole | 2‑(2‑Hydroxy‑3‑tert‑butyl‑5‑methylphenyl)‑5‑chlorobenzotriazole (Tinuvin 326 type) | 2‑Hydroxy‑4‑(octyloxy)benzophenone (Uvinul 3008 type) |
|---|---|---|---|
| λmax (CH₂Cl₂) | 350 nm | 345 nm | 290, 325 nm |
| Molar extinction coefficient at λmax | 20 100 L·mol⁻¹·cm⁻¹ | 16 500 L·mol⁻¹·cm⁻¹ | 9 200 / 11 300 L·mol⁻¹·cm⁻¹ |
| TGA 5 % weight loss (N₂, 10 °C/min) | 235 °C | 262 °C | 198 °C |
| Extractability after 10 d in 95 % ethanol, 25 °C | <0.09 % of initial | <0.06 % | 0.32 % |
| Photo‑oxidation induction time in LDPE (biaxial stretch, 80 °C, 0.35 W/m² at 340 nm) | 1 940 h | 2 210 h | 1 250 h |
