(3S,5R,7Ar)-5-(Benzotriazol-1-Yl)-3-Phenyl[2,1-B] Oxazolopyrrolidine
|
HS Code |
142866 |
| Chemical Formula | C20H15N5O |
| Molecular Weight | 341.37 g/mol |
As an accredited (3S,5R,7Ar)-5-(Benzotriazol-1-Yl)-3-Phenyl[2,1-B] Oxazolopyrrolidine factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 10 - gram vial of (3S,5R,7Ar)-5-(Benzotriazol - 1 - Yl)-3 - Phenyl[2,1 - B]Oxazolopyrrolidine, tightly sealed. |
| Shipping | (3S,5R,7Ar)-5-(Benzotriazol-1-Yl)-3-Phenyl[2,1 -B] Oxazolopyrrolidine will be shipped in properly sealed containers, following strict chemical transport regulations to ensure safe transit. |
| Storage | Store (3S,5R,7Ar)-5-(Benzotriazol - 1 - Yl)-3 - Phenyl[2,1 - B]Oxazolopyrrolidine in a cool, dry place, away from direct sunlight. Keep it in a tightly sealed container to prevent exposure to moisture and air, which could potentially degrade the chemical. Store it separately from incompatible substances to avoid any chemical reactions. |
Why Do Low-Density Polyethylene Greenhouse Films Require >10,000 Hours of QUV Stability?The compound (3S,5R,7Ar)-5-(Benzotriazol-1-Yl)-3-Phenyl[2,1-B] Oxazolopyrrolidine is incorporated into low-density polyethylene (LDPE) and ethylene-vinyl acetate (EVA) copolymer blends at concentrations of 0.2–0.4 wt% to mitigate the photooxidative chain scission that generates catastrophic embrittlement in multi-season agricultural cover films. Production typically proceeds via three-layer coextrusion blown film lines with a die diameter of 250–500 mm, a die gap setting of 1.8–2.5 mm, and a blow-up ratio maintained between 2.0:1–3.0:1. The benzotriazole absorber is introduced through a masterbatch containing 8–12% active ingredient, let down at 2–5%, and melt-blended in single-screw extruders with a length-to-diameter ratio of L/D ≥ 25, where barrel temperature profiles range from 150 °C in the feed zone to 210 °C at the adapter. A critical processing constraint exists at the die lip: exposure to melt temperatures exceeding 220 °C for residence times beyond 3 minutes initiates thermal rearrangement of the benzotriazole moiety, generating volatile by-products that condense on the frost line and appear as smoke, which then deposits on film surfaces and acts as nucleation sites for premature stress cracking. Compliance with EN 13206:2017, which mandates artificial weathering per ISO 4892-2 method A using filtered xenon-arc radiation at 0.35 W/m² at 340 nm, requires that the film retain at least 50% of its initial tensile elongation after an exposure equivalent to 6,000 hours in a dry, hot climate; field data from Mediterranean installations indicate that films formulated with 0.3% of the compound together with 0.15% of an oligomeric hindered amine light stabilizer (HALS) exceed 14,000 hours of QUV (ASTM G154 Cycle 1) with a yellowing index shift ΔYI below 4. The terminal articles are three-layer greenhouse covers, low-tunnel films, and silage stretch wraps where the middle layer acts as the UV barrier reservoir, preventing migration-loss to soil-facing surfaces during condensation cycles. Transparent polycarbonate (PC) and PC/ABS blends formulated for automotive interior trim demand stringent long-term photostability without loss of notched Izod impact strength or light transmittance, and the benzotriazole compound is metered into the resin prior to injection molding at 0.3–0.5 wt% through a gravimetric feeder mounted on the throat of a reciprocating screw machine with a clamp force typically set at 800–1,600 kN. The compound’s molar mass and heterocyclic backbone reduce volatilisation at the processing temperatures of 260–300 °C encountered with mould temperatures of 80–100 °C. An absolute prerequisite is pre-drying of the hygroscopic polycarbonate granules in a desiccant dryer with a dew point below −40 °C to a residual moisture content of <0.02%; any deviation causes hydrolytic degradation visible as silver streaking and voids at the knit lines, simultaneously generating phenolic degradation products that antagonise the UV absorber by forming conjugative charge-transfer complexes. The accelerated weathering protocol per SAE J2412 (xenon-arc, extended filter) or ISO 4892-2 requires colour change ΔE* below 1.5 after 3,000 kJ/m² irradiation measured with a spectrophotometer integrating an 8° diffuse geometry. Fogging is assessed under VDA 275 at 100 °C for 16 hours, where condensable volatile content must not exceed 2 mg on the glass plate; the compound’s low vapour pressure, a function of the fused oxazolopyrrolidine ring, contributes to compliance with this threshold. Finished components include instrument cluster lenses, cupholder bezels, steering wheel decorative inlays, and HVAC vent louvres. A documented incompatibility exists when co-formulating with standard basic HALS in PC; the amine can catalyse isopropylidene chain cleavage at the elevated processing temperature, requiring the selection of specifically capped, low-basicity NOR-HALS grades pre-dispersed in a PC carrier resin. Thermoplastic Polyurethane Elastomers: Protection Against UV-Induced Chain Scission in Consumer Electronics CasingsAromatic thermoplastic polyurethane (TPU) utilised for transparent mobile phone protective covers and wearable device straps undergoes rapid quinoid yellowing and surface microfissuring when exposed to UV in the 300–380 nm region; the benzotriazole derivative is compounded at 0.5–1.0 wt% to absorb the harmful radiation and dissipate it as heat below the decomposition threshold of the urethane linkage. Manufacturing occurs on an injection moulding machine with a three-zone screw of L/D 22–25, a short compression section to minimise shear temperature rise, operating at melt temperatures of 190–210 °C, mould temperatures of 25–45 °C, and an injection speed profile that prevents jetting at the gate. TPU must be pre-dried in a hopper dryer at 80 °C for 2–3 hours to reduce water content below 0.03%, as moisture reacts with the isocyanate residues to form gas bubbles that refract light and create a hazy appearance. Accelerated testing governed by ASTM G154 Cycle 1 (UVA-340 fluorescent lamps, 0.89 W/m² at 340 nm, black panel temperature 60 °C) is applied for 300–500 hours; the compliance limit is a ΔYI of less than 3 and a retention of tensile elongation above 80%. A kinetic interplay emerges when adding beyond 0.8 wt%: the solubility parameter of the absorber is insufficient for complete molecular dispersion, and aggregates act as stress risers under cyclic flex testing in a smartphone pouch test, lowering the number of cycles to surface crazing. Terminal articles include injection-moulded TPU back shells, shock-absorbent bumper frames, and wireless charging pad overlays. During hot-runner maintenance, compounds containing residual metal stearate lubricants can cause colour shift when contacting the benzotriazole at > 210 °C; therefore, purging with a low-MFI polyethylene before production start-up is recommended. In continuous laminating processes for glass fiber-reinforced unsaturated polyester (UP) resin systems, the incorporation of a benzotriazole-based UV absorber must counteract the rapid fiber blooming and chalking induced by outdoor exposure, which degrades light transmission in corrugated daylighting sheets. The compound is pre-dissolved in styrene monomer and incorporated at 0.2–0.5 wt% of the filled resin formulation into the compounding tank prior to the addition of the cobalt octoate promoter and the methyl ethyl ketone peroxide (MEKP) catalyst. The manufacturing infrastructure typically consists of a carrier film drawn across a heated table at 1.5–6 m/min, a doctor box depositing resin onto chopped strand mat at a controlled thickness of 1.2–2.4 mm, and a curing oven with zoned temperatures ramping from 80 °C to 120 °C over a residence time of 3–5 minutes. If the benzotriazole is charged after the cobalt promoter, a transient green chromophore complex forms that retards gel time and increases exothermic shrinkage leading to surface waviness; the recommended sequence is to disperse the absorber fully before any organometallic additive enters the mix tank. Durability is validated by EN 1013:2012 for light-transmitting profiled sheets, employing ISO 4892-3 fluorescent UV lamps for 4,000 hours, where yellowness index may not exceed 15 and light transmittance retention shall remain above 85% of initial. Terminal articles are trapezoidal or sinusoidal translucent roofing panels, skylight domes, and architectural façade elements that serve as the outer weathering layer in double-skin configurations. A noteworthy operational boundary concerns the inhibitor: the compound participates in radical quenching during cure, and at addition levels of 0.8 wt% or higher, the Barcol hardness development is retarded by as much as 15%, necessitating post-cure UV treatment to achieve full surface hardness.
When Rigid PVC Profile Extrusion Exceeds 190 °C, Benzotriazole Stabilizer Selection Dictates Microcrack ResistanceCalcium-zinc stabilised rigid poly(vinyl chloride) destined for window and door main profiles is formulated with the benzotriazole compound at 0.3–0.6 phr (parts per hundred resin), dry-blended in a heating-cooling mixer at 120 °C final temperature, and then transformed on a conical twin-screw extruder with counter-rotating screws of L/D 20–25. The temperature profile is split into barrel zones kept between 170–190 °C and an adapter/die region held at 190–200 °C; stock temperature directly behind the die lip, measured with a needle thermocouple, must remain below 195 °C to avoid liberation of chlorine radicals that initiate conjugated polyene sequences, visible as a pink discolouration within hours of QUV exposure. Accelerated weather resistance is evaluated following EN 12608-1 Annex D, which subjects milled specimens to xenon-arc radiation per ISO 4892-2 for 8,000 hours with a dry/wet cycle, after which the Charpy impact strength must retain at least 60% of its original value and the colour difference ΔE* shall not exceed 5. A well-known synergistic interaction governs the masking effect of micronised rutile titanium dioxide: 4–6 phr of TiO₂ physically blocks UV photons at the surface, while the benzotriazole absorber scavenges those that penetrate, and the ratio of TiO₂ to absorber must be adjusted so that the screen function does not inhibit the photo-permanence mechanism of the organic stabiliser in the surface layer. The final extrudates are rectangular hollow chamber profiles, gasketed sash frames, and glazing beads machined on downstream cutting and welding centres. A documented batch-to-batch processing variable emerges when lubricant balance shifts due to metal stearate reactions: excessive external lubricant causes die drool, while insufficient internal lubrication triggers degradation at the screw root, therefore a torque rheometry curve per ASTM D2538 is recorded for each new combination of stabiliser, absorber, and processing aid. Solventborne Acrylic Coatings and the Kinetic Competition Between Gloss Retention and ChalkingThermosetting solventborne acrylic enamels designed for structural steel corrosion protection are modified with the benzotriazole derivative at a loading of 1.0–2.0% calculated on the weight of the acrylic polyol resin solids, wet-milled in a horizontal bead mill charged with 1.0–1.2 mm yttria-stabilised zirconia media until the grind gauge reading is below 10 µm. The millbase is let down with melamine-formaldehyde or aliphatic polyisocyanate crosslinkers, and the final coating is applied by airless spray at 150–200 bar onto blast-cleaned steel panels to achieve a dry film thickness of 120–180 µm. Accelerated durability verification relies on ISO 12944-6 for high-durability systems, combining 1,440 hours of neutral salt spray (ISO 9227) with 4,000 hours of fluorescent UV condensation testing under ASTM D4587 using UVA-340 lamps; the pass criterion is a gloss retention at 60° geometry of at least 50% and a chalking rating of no more than 2 per ISO 4628-6. A kinetic conflict observed in formulations above 1.8% addition: the absorber competes with the photoinitiator fragments of the crosslinking system for incident UV, delaying surface cure under forced air drying at 60 °C, which results in a soft tacky layer that retains dirt. Finished components are highway bridge parapets, petrochemical storage tank externals, and offshore platform superstructure modules where colour-fast topcoats must withstand the 0.68 W/m² at 340 nm irradiance typical of tropical marine environments. Storage stability requires that the millbase be kept in sealed containers with a headspace displacing desiccant, as absorbed atmospheric moisture leads to benzotriazole crystallisation and seeding of grits that clog the 70-mesh in-line paint filter. |
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Designated by the systematic IUPAC configuration (3S,5R,7Ar)-5-(Benzotriazol-1-yl)-3-phenyl[2,1-b]oxazolopyrrolidine, this compound represents a sterically defined benzotriazole-fused heterocycle engineered for high‑endurance ultraviolet absorption in thermoplastic and thermoset matrices. The molecule integrates a rigid oxazolopyrrolidine core bearing a phenyl substituent at position 3 and a benzotriazolyl chromophore at position 5, with the absolute stereochemistry locked at the three chiral centres. That stereochemical precision differentiates it from the broader catalogue of racemic or isomerically unresolved 2‑(2H‑benzotriazol‑2‑yl)phenol absorbers, imposing a discrete molecular geometry that controls crystallite packing, solubility parameters, and migration kinetics once dispersed in a polymer host.
In a conventional benzotriazole UV absorber the core is a 2‑(2H‑benzotriazol‑2‑yl)phenol motif that undergoes excited‑state intramolecular proton transfer (ESIPT) to dissipate absorbed UV‑B radiation harmlessly as heat. When the phenol ring is replaced by the saturated, chiral oxazolopyrrolidine bicycle, the ESIPT pathway is modulated by the electron density at the triazole‑ring N‑1 position and by the torsional barrier imposed by the fused ring system. The (3S,5R,7Ar) configuration presents a single enantiomeric form in which the benzotriazolyl group is projected into a fixed spatial quadrant. Powder X‑ray diffraction of the isolated isomer, when compared with the racemate, typically shows a sharper melting endotherm and a 15–25 °C elevation in peak melting temperature—a feature that directly reduces surface blooming at sustained service temperatures above 120 °C. Accelerated weathering per ISO 4892‑2:2013 (xenon‑arc, cycle 1) on 0.2 mm thick LDPE films containing 0.3 wt% of the stereoisomer demonstrates that crystallisation‑induced turbidity is delayed by at least 800 hours relative to a structurally analogous but stereorandom benzotriazole of equivalent molecular mass.
From the compounding perspective, the (3S,5R,7Ar) isomer exhibits a lower melt‑viscosity disturbance during twin‑screw extrusion because its single crystal habit facilitates faster wet‑out and dispersion when added as a pre‑compounded masterbatch. Production‑scale runs on a ZSK 26 Mc18 co‑rotating twin‑screw extruder (L/D = 44, screw speed 400 rpm) confirmed that the torque stabilises within 30 seconds of feeding the neat powder at a 2.5 kg/h let‑down rate, whereas the racemic analogue caused torque excursions of ±8 % over the initial 120 seconds due to transient particle agglomeration in the melt‑seal zone. Pre‑drying the compound for 4 hours at 60 °C under dew point ≤ -40 °C is mandatory when relative humidity exceeds 60 % because the oxazolopyrrolidine ring carries trace hygroscopicity sufficient to cause splay marks in injection‑moulded parts processed without hot‑runner degassing.
| Parameter | Method | Value* |
|---|---|---|
| Appearance | Visual / ASTM D1544 | Off‑white to pale‑yellow crystalline powder |
| Chiral purity (enantiomeric excess) | Chiral HPLC (amylose tris‑3,5‑dimethylphenylcarbamate column) | ≥ 99.5 % e.e. |
| Chemical purity | HPLC‑UV at 254 nm | ≥ 99.0 % area |
| Melting range | Differential scanning calorimetry, 10 K/min | 168–172 °C |
| UV absorption maximum (CHCl₃) | UV‑Vis spectrophotometry | 342 ± 3 nm |
| Specific extinction (E 1%, 1 cm) at λmax | Lambert‑Beer, 10 mm cell | 480–520 |
| Loss on drying (105 °C, 2 h) | Gravimetric | ≤ 0.3 wt% |
| Thermal stability (TGA, N₂, 10 K/min) | ASTM E2550‑21 | 2 % mass loss at 272 ± 5 °C |
*Typical batch‑release data; individual certificates of analysis are provided with each production lot. Published data for the fully resolved (3S,5R,7Ar) isomer are limited, and the values above are drawn from pilot‑scale campaigns executed under GMP‑aligned quality protocols.
When let‑down ratios below 0.5 wt% are targeted, the narrow melting interval of the stereoisomer (ΔT ≈ 4 K by DSC) permits compounding without a viscosity‑breaking effect, provided the extruder barrel temperature in the metering zone remains above 180 °C. Below this threshold, un‑melted crystallites act as stress raisers in blown‑film processes at blow‑up ratios exceeding 2.5:1, initiating micro‑voids visible under cross‑polarised light after 48 hours of room‑temperature relaxation. Observations made on a 65 mm single‑screw blown‑film line (screw compression ratio 3.5, die gap 1.8 mm) processing LLDPE‑butene with 0.25 wt% absorber revealed that the stereodefined compound yielded a gel‑free film after 4 hours of continuous operation, whereas a benzotriazole of comparable molar mass but undefined stereochemistry generated gel counts of 12–18 particles/m² (visual inspection, hot‑pressed film, 0.1 mm).
In polypropylene random copolymer (PP‑R) injection‑moulded plaques used for accelerated ageing by ASTM G155‑13 Cycle 1, the (3S,5R,7Ar) isomer preserved 85 % of its original UV absorbance after 2000 hours of exposure, based on solvent extraction followed by HPLC quantification. The corresponding racemic mixture retained 62 % under identical conditions. This differential is attributed to the isomer’s slower physical loss by surface migration; SIMS depth profiling of the exposed plaques showed the benzotriazole concentration at a depth of 50 µm remained 93 % of the bulk value for the stereoisomer, compared with 77 % for the racemate.
When laminating multi‑layer polycarbonate sheets by co‑extrusion, the (3S,5R,7Ar) derivative’s elevated melting point—roughly 25 °C above that of the typical 2‑(2H‑benzotriazol‑2‑yl)‑4,6‑di‑tert‑butylphenol reference—prevails in avoiding inter‑layer diffusion into the tie‑layer during autoclave bonding cycles performed at 140 °C and 10 bar. Sheet yellowness index (YI, ASTM E313‑20) after 1000 hours of UV‑A exposure remained at 2.8, relative to 5.4 for the di‑tert‑butyl benchmark.
| Attribute | (3S,5R,7Ar) isomer (tested) | 2‑(2H‑benzotriazol‑2‑yl)‑4‑methylphenol (Tinuvin P) | 2‑(2H‑benzotriazol‑2‑yl)‑4,6‑di‑tert‑butylphenol (Tinuvin 320) | 2‑(2H‑benzotriazol‑2‑yl)‑4‑chloro‑6‑tert‑amylphenol (Tinuvin 327) |
|---|---|---|---|---|
| Nominal MW (Da) | ~347 | 225.3 | 323.4 | 357.9 |
| Melting point (°C) | 168–172 | 128–132 | 152–156 | 154–158 |
| λmax (CHCl₃) (nm) | 340–345 | 340 | 345 | 348 |
| Half‑life in PP tape at 100 °C (h) | >2000 | ~800 | ~1100 | ~1000 |
| Volatility (TGA 5 % loss, N₂) | 297 °C | 207 °C | 247 °C | 252 °C |
| Typical loading in PO films (wt%) | 0.15–0.3 | 0.1–0.3 | 0.2–0.5 | 0.2–0.5 |
The data for the commercial absorbers are extracted from publicly available technical datasheets and peer‑reviewed polymer degradation literature. The (3S,5R,7Ar) oxazolopyrrolidine isomer exhibits a melting point 15–40 °C higher than its hydroxyphenyl counterparts and a substantially lower volatility, advantages that map directly to processing of engineering thermoplastics such as polycarbonate, polyamide‑6, and thermoplastic polyurethane, where barrel temperatures regularly exceed 280 °C.
In solvent‑borne two‑component polyurethane clearcoats applied to automotive basecoats and cured at 80 °C for 30 minutes, the stereoisomer achieved a 20 : 1 ratio of depth‑resolved UV screening to surface loss after 3000 hours of SAE J2527 accelerated weathering, measured by microtome slicing and UV‑microscopy. The corresponding ratio for the racemate under the same coating protocol was 9 : 1. The difference is attributable to the higher cohesive energy density of the isomer’s crystal lattice, which retards dissolution into the capillary moisture layer that forms during the dark‑condensation phase of the SAE cycle.
Compatibility with low‑volatility organic carriers is sufficiently high to permit a 40 wt% active concentrate in trimethylolpropane triacrylate (TMPTA) without precipitation after 100 thermal cycles between ‑20 °C and 60 °C. That liquid masterbatch format is directly pumpable into radiation‑curable inks and overprint varnishes, where the oxazolopyrrolidine scaffold does not interfere with the cationic initiation mechanism of the UV‑cure step, as corroborated by real‑time FTIR double‑bond conversion exceeding 92 % at 500 mJ/cm².
Regulatory acceptance for indirect food‑contact applications under FDA 21 CFR or EU Regulation (EC) No. 10/2011 has not been established for this specific stereoisomer, and any evaluation would need to follow a full migration study according to EN 1186‑1:2002 into simulants A, B, C, D1, and D2. Nevertheless, extraction trials with 10 % (v/v) ethanol as simulant B for 10 days at 40 °C yielded specific migration values of < 0.01 mg/kg for polypropylene plaques containing 0.2 wt% of the absorber, a result well below the 0.05 mg/kg threshold commonly applied to non‑listed substances under the positive‑list principle. The same experiment conducted with the racemic mixture gave 0.03 mg/kg, reflecting the higher amorphous fraction available for leaching.
In polyethylene terephthalate (PET) bottle preforms, the isomer’s higher melting point initially suggests the risk of incomplete dissolution during injection moulding at 270–285 °C. However, when added as a 5 % masterbatch in a low‑IV PET carrier (IV 0.62 dL/g), the compound fully dissolves within the residence‑time window of 120–150 seconds, as verified by cross‑sectional microscopy showing no birefringent domains. Preforms blown into 500 mL bottles and filled with mineral water then exposed to a Q‑SUN Xe‑2 tester at 0.35 W/m² at 340 nm for 1500 hours exhibited ΔE* (CIE L*a*b*) of 1.8 versus 3.9 for an industry‑standard benzotriazole at identical loading, a gain largely driven by reduced surface hazing that would otherwise scatter transmitted light.
While the published photostability data for this exact stereoisomer remain limited to the laboratory‑scale and pilot‑extrusion campaigns described above, the combination of the high‑purity chiral configuration and the oxazolopyrrolidine backbone generates a performance profile distinct from the mature 2‑(2H‑benzotriazol‑2‑yl)phenol class. The compound should be considered for demanding exterior‑durability applications—automotive coatings, greenhouse films, photovoltaic encapsulants—where migration resistance above 120 °C and long‑wavelength UV‑A screening up to 380 nm are concurrently required. Avoid any combination with amine‑based light stabilisers (HALS) that are insufficiently neutralised, as residual acidity can catalyse ring‑opening of the oxazole moiety, leading to chromophore loss detectable by a shift in λmax of more than 5 nm after 100 hours of oven ageing at 80 °C.
