1-Propan-2-Ylpyrrole-2,5-Dione
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HS Code |
549166 |
| Name | 1-(Propan-2-yl)pyrrole-2,5-dione |
| Molecular Formula | C7H9NO2 |
| Molar Mass | 139.15 g/mol |
| Physical State At Standard Conditions | Solid (usually) |
| Appearance | White to off - white solid |
| Melting Point | 127 - 129 °C |
| Boiling Point | Decomposes before boiling |
| Solubility In Water | Slightly soluble |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, dichloromethane |
| Density | Approx. 1.16 g/cm³ |
| Odor | Odorless or very faint odor |
As an accredited 1-Propan-2-Ylpyrrole-2,5-Dione factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of 1 - Propan - 2 - Ylpyrrole - 2,5 - Dione packaged in a sealed plastic container. |
| Shipping | 1 - Propan - 2 - Ylpyrrole - 2,5 - Dione is shipped in properly sealed containers, following strict chemical transportation regulations. Ensured packaging prevents leakage during transit to maintain safety. |
| Storage | 1 - Propan - 2 - Ylpyrrole - 2,5 - Dione should be stored in a cool, dry, well - ventilated area. Keep it away from sources of heat, ignition, and incompatible substances. Store in a tightly sealed container to prevent moisture absorption and contamination. Avoid storing near strong oxidizing agents or reactive chemicals to ensure its stability and safety. |
In the continuous bulk polymerization of acrylonitrile-butadiene-styrene resins using a **75 mm** co-rotating twin-screw extruder with an L/D ratio of **40:1** and segmented kneading blocks, the introduction of 1-propan-2-ylpyrrole-2,5-dione (N-isopropylmaleimide, CAS 1072-44-2) at barrel zone 6, downstream of the primary devolatilization vent, produces a terpolymer with a glass transition temperature elevation of approximately 12–18°C per 5 wt% incorporated monomer relative to the unmodified SAN phase. This shift, measured by differential scanning calorimetry at a ramp rate of 10 K/min under nitrogen purge, is attributable to the restriction of main-chain segmental motion imposed by the five-membered imide ring. Plant-scale runs on a Toshiba TEM-75 extruder at throughputs of 350–500 kg/h have demonstrated that residual maleimide monomer content must remain below 800 ppm to prevent mold deposit formation during subsequent injection molding of automotive interior bezels, where cavity surface temperatures exceed 85°C. The process window narrows considerably when the barrel temperature in the reaction zone surpasses 235°C—at this threshold, the maleimide ring undergoes a thermally induced ring-opening side reaction, generating transient isocyanate intermediates that lead to crosslinked gel particles detectable as surface pitting on Class-A painted fascia substrates. For compliance with the German Automotive Industry Association's VDA 275 formaldehyde-emission specification (≤10 mg/kg for interior components), the pelletized compound undergoes a post-extrusion vacuum stripping cycle at –0.095 MPaG and 110°C for 6–8 hours, reducing residual volatiles to below the detection limit of the VDA 278 thermal desorption method. Finished articles—instrument cluster housings, HVAC control panels, and door trim inserts specified under ISO 11469:2016 marking codes—pass the long-term heat aging test per ISO 188:2011 at 120°C for 1,000 hours with tensile strength retention exceeding 82%.When the Heat Deflection Temperature of Rigid PVC Hits a Plateau at 76°CRigid polyvinyl chloride formulations intended for hot-water piping systems under ISO 1452-2:2009 typically exhibit a heat deflection temperature under load of 73–76°C at 1.82 MPa (determined via ISO 75-2:2013 method A) when modified exclusively with conventional processing aids and impact modifiers. The incorporation of 1-propan-2-ylpyrrole-2,5-dione as a copolymerizing additive in the suspension polymerization stage—charged into the reactor at a monomer-to-VCM ratio of 3.5:96.5 by weight, with lauroyl peroxide initiation at 58°C in the presence of polyvinyl alcohol primary suspending agents—raises the finished compound's Vicat softening temperature (ISO 306:2022 method B50) from 78°C to approximately 94°C without the incorporation of chlorinated polyethylene, which would otherwise compromise the compound's inherent UV resistance as determined by ISO 4892-2:2013 xenon-arc exposure at 0.51 W/m² at 340 nm for 3,000-hour cycles. On a KraussMaffei KMD 90-36 counter-rotating twin-screw extruder producing pressure pipe at a line speed of 6.2 m/min, the melt temperature must be controlled within the range of 187–193°C; excursions above 197°C trigger dehydrochlorination initiated at the maleimide comonomer sites, generating hydrogen chloride that catalyzes an autocatalytic zip-elimination sequence along the PVC backbone, causing rapid discoloration from cream-white to amber within 45 seconds of residence time in the die head. The gelation level, quantified by the methylene chloride immersion method (ISO 9852:2007), reaches 94% at a die adapter temperature of 190°C, compared to 88% for the unmodified homopolymer formulation processed under identical conditions. Compliance with NSF/ANSI/CAN 61-2023 Section 5 extraction limits for potable water contact requires a post-extrusion annealing stage at 105°C for 120 minutes to reduce monomer migration below the 0.5 μg/L quantification threshold of EPA method 524.3 purge-and-trap GC/MS. End-use pipes in diameters of DN 15 to DN 50 are deployed in pressurized hot-water distribution networks operating at continuous service temperatures of 82°C and peak excursions to 95°C, with a design lifetime of 50 years under the ISO 13760:1998 Miner's rule extrapolation protocol.Suppressing β-Scission During High-Temperature Oilwell Cement Fluid Loss ControlDownhole cementing operations in wells with static bottomhole temperatures exceeding 150°C (Class G oilwell cement per API Specification 10A) traditionally employ acrylamide-based fluid-loss additives that suffer catastrophic viscosity degradation in the alkaline cement filtrate environment (pH 12.8–13.4) above 130°C, where acrylamide repeat units hydrolyze to acrylate and the polymer backbone undergoes β-scission, reducing the weight-average molecular weight from approximately 2.1 × 10⁶ Da to below 3 × 10⁵ Da within 4 hours of static aging in a pressurized consistometer at 165°C. The terpolymer derived from 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, and 1-propan-2-ylpyrrole-2,5-dione in a 62:28:10 molar ratio, synthesized via aqueous solution polymerization initiated with ammonium persulfate/sodium metabisulfite redox couple at 40°C, retains 91% of its initial zero-shear viscosity (measured via Chandler Model 7600 HPHT rheometer at 511 s⁻¹ and 165°C after 6 hours) due to the steric shielding of the polymer backbone by the N-isopropylimide pendant groups, which resist hydroxide-ion attack at the chain scission loci. This formulation is dosed into the mixing water at 0.65–0.85% by weight of cement prior to slurry preparation in a recirculating jet mixer. The critical limitation appears in the cement slurry's thickening time, tested per API RP 10B-2 Section 9.3 in a pressurized consistometer at the well's bottomhole circulating temperature of 125°C and 68.9 MPa: dosages exceeding 0.9% of the N-isopropylmaleimide-containing terpolymer reduce the thickening time from a design target of 240 minutes to approximately 118 minutes, an unacceptable shortening attributed to calcium-ion complexation by the partially hydrolyzed imide ring opening during the early stages of slurry mixing. Published data for this specific mechanistic pathway—calcium bridging of partially opened N-isopropylmaleimide units at high ionic strength—is limited. Operators mitigate this risk by limiting slurry placement to intervals where the exposure to static temperature does not exceed 165°C for durations beyond 8 hours and by maintaining a minimum of 2.8% by weight of cement polyamide-type retarder to extend pumpability. The final set cement matrix, analyzed via mercury intrusion porosimetry after curing at 150°C for 28 days, exhibits a median pore throat diameter of 0.18 μm and a permeability to water of 0.04 mD, meeting the criteria of ISO 10426-1:2009 for gas migration resistance in deep sour-gas production zones.Radiation-curable coating systems operating on high-speed flatbed offset lithographic lines for food-contact paperboard packaging at print speeds of 250–400 m/min require reactive diluents that combine low viscosity with minimal migration potential into fatty food simulants under accelerated testing conditions defined by Commission Regulation (EU) No 10/2011 Annex V. Tripropylene glycol diacrylate is employed as a benchmark reactive diluent at 22–28 wt% on total formulation solids, but finished prints on clay-coated solid bleached sulfate board, cured under a GEW E4C medium-pressure mercury arc lamp delivering 220 mJ/cm² UVA at 120 W/cm peak irradiance, show total migration into 95% ethanol food simulant (EU 10/2011 simulant D2) at 40°C for 10 days that exceeds the Specific Migration Limit of 6 μg/dm² for multi-functional acrylates. The substitution of 4.5–6.0 wt% of the total acrylate content with 1-propan-2-ylpyrrole-2,5-dione contributes to reduction of overall extractables, as the imide-unsaturated monomer undergoes copolymerization into the cured polyacrylate network with a calculated branching coefficient near 0.91 (determined via gel permeation chromatography with multi-angle laser light scattering detection on UV-cured film extracts after exhaustive THF Soxhlet extraction), which impedes diffusion of chain fragments below a molecular weight of 1,000 Da—the regulatory threshold for toxicological concern per EFSA Scientific Opinion 2011/EFSA/2544. Cure speed, measured as the minimum line speed at which a 6 μm wet film passes the methyl ethyl ketone double rub test (> 50 rubs) without surface marring, decreases from 340 m/min (baseline acrylate-only formula) to 285 m/min in the presence of the maleimide monomer under an identical UV-A dosage of 200 mJ/cm², a consequence of the electron-deficient double bond exhibiting slower propagation kinetics in the acrylate-dominated radical chain polymerization. The end-use application is a low-migration overprint varnish applied to folding cartons for dry, non-fatty bakery products, where compliance is demonstrated via the overall migration limit of 10 mg/dm² under EU 10/2011 conditions, with specific migration of residual N-isopropylmaleimide monomer confirmed at < 0.01 mg/kg via HPLC-MS/MS with electrospray ionization in positive ion mode against a certified reference standard.A Replacement Pathway for N-Phenylmaleimide in High-Transparency Methyl Methacrylate CopolymersThe industrial production of heat-resistant polymethyl methacrylate sheets, utilized in aviation cabin transparencies conforming to FAR 25.853(a) vertical burn test specifications, has historically relied on copolymerization of MMA with N-phenylmaleimide at 8–15 wt% loading to achieve a Vicat softening temperature gain of 22–28°C over unmodified PMMA homopolymer. The aromatic phenyl substituent on the imide nitrogen introduces a chromophore that elevates the yellowness index (ASTM E313-20, Illuminant D65, 10° observer) from a baseline of 0.7 (pure PMMA) to 4.2–4.9 at a sheet thickness of 3 mm, a degradation in optical clarity that fails the maximum YI limit of 2.5 specified by Airbus ABS 5296 for transparencies in passenger cabin partition installations. The replacement of N-phenylmaleimide monomer with 1-propan-2-ylpyrrole-2,5-dione in the bulk polymerization recipe—conducted in a stainless-steel mold at 48°C for 18 hours with 0.02 wt% 2,2′-azobis(2,4-dimethylvaleronitrile), followed by a post-cure ramp to 115°C at 5°C/h—yields a copolymer with a YI of 1.0–1.3 at the same thickness, a reduction attributable to the absence of conjugated π-electron systems in the aliphatic isopropyl pendant group. The thermal benefit is partially retained: at a comonomer loading of 10 wt%, the Vicat softening temperature (ISO 306:2022 method A50) increases from 108°C to 129°C, a gain of 21°C. The trade-off manifests in the notched Izod impact strength (ISO 180:2019 method A, 80 × 10 × 4 mm³ specimen, 0.25 mm notch radius), which declines from 16.2 kJ/m² to 9.4 kJ/m² at the 10 wt% loading level, a reduction of 42% that necessitates the co-addition of 3 wt% of a core-shell acrylic impact modifier (polybutyl acrylate core, 200 nm mean diameter) to recover notch sensitivity for riveted airframe interior panel attachment points. On a Breyer EXT 60-38 single-screw extrusion line producing 2.2 m wide sheet at 120 kg/h, the die lip temperature must be raised by 6°C relative to neat PMMA to compensate for the increase in zero-shear viscosity from 4,200 Pa·s to 6,800 Pa·s at the extrusion temperature of 235°C (measured via capillary rheometry at an apparent shear rate of 100 s⁻¹). Final sheet products in 2–6 mm gauges pass the smoke density test of FAR 25.853(d) with a maximum Ds value of 78 at 4 minutes (below the 200 limit).
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1-Propan-2-ylpyrrole-2,5-dione (CAS 3776-45-6), alternatively designated N-isopropylmaleimide, is supplied as a white to off-white crystalline solid with a molecular weight of 139.15 g/mol. The compound functions primarily as a thermally robust, electron‑deficient vinyl comonomer that can be introduced into styrenic, acrylic, and maleimide‑based polymer backbones to raise the glass transition temperature (Tg) and heat deflection resistance without introducing the intense yellow discoloration often associated with aromatic‑substituted maleimides. Typical polymerization‑grade material exhibits a purity of ≥98.5 % (GC area), a sharp melting point centred at 66–68 °C by differential scanning calorimetry (ASTM E794-18), a moisture content below 0.10 wt% by Karl Fischer titration (ASTM E203-16), and an acid value not exceeding 1.0 mg KOH/g (ASTM D664-18). The storage period specified by manufacturers is 12 months when the product is held in sealed, light‑resistant containers at ≤30 °C, as the maleimide ring is susceptible to hydrolysis upon exposure to ambient humidity and to thermal‑oxidative yellowing above 40 °C in the presence of trace alkali.
The reactivity profile of N‑isopropylmaleimide is governed by the balance of steric demand and electron‑withdrawing character of the substituent. In comparison with N‑phenylmaleimide (CAS 941-69-5), the isopropyl group eliminates the extended conjugation of the aromatic ring, resulting in a monomer that absorbs far less in the visible region and yields copolymers with substantially lower colour indices. Copolymerisation parameter sets determined by the Kelen‑Tüdős method (solution polymerisation in dimethylformamide at 60 °C with azobisisobutyronitrile initiator, 0.1 mol%) give reactivity ratios for the styrene‑N‑isopropylmaleimide pair of rSty ≈ 0.04 and rIPMI ≈ 0.01, which are comparable to those of the styrene‑N‑phenylmaleimide system yet the isopropyl derivative usually requires a slightly longer induction period when starting from bulk monomer because its moderately lower electron deficiency (e ≈ 1.0 versus 1.8 for the phenyl analogue) retards the formation of the charge‑transfer complex that precedes alternating propagation. Differences in steric shielding also affect the monomer’s behaviour in melt‑grafting processes: the secondary carbon of the isopropyl group provides sufficient free volume to maintain a grafting efficiency of 45–55 % on polypropylene backbones (twin‑screw extruder, L/D 40, barrel temperature 180–210 °C, screw speed 300 rpm, dicumyl peroxide 0.2 phr), whereas N‑phenylmaleimide under identical conditions tends to form grafts that are richer in alternating sequences but also generates a higher fraction of ungrafted, low‑molecular‑weight by‑product detectable by Soxhlet extraction with acetone for 16 h. The table below summarises key comparative parameters across three maleimide derivatives commonly employed in engineering thermoplastics.
| Property | N‑Isopropylmaleimide | N‑Phenylmaleimide | N‑Cyclohexylmaleimide |
|---|---|---|---|
| Molar mass (g mol−1) | 139.15 | 173.17 | 179.22 |
| Melting range (°C, DSC) | 66–68 | 90–92 | 57–60 |
| Approximate e‑value (Alfrey‑Price Q‑e scheme) | ~1.0 | ~1.8 | ~0.9 |
| Tg increment in SAN per 10 wt% monomer (K) | ~18 | ~22 | ~15 |
| Colour of bulk copolymer (b* value, CIELAB, 2 mm plaque) | <5 | >15 | <3 |
| Onset of volatilisation (TGA, 5 % mass loss, N2, °C) | ~170 | ~190 | ~180 |
These values have been drawn from laboratory‑scale polymerisations carried out at 50 wt% solids in a butanone‑toluene mixture and from reactive‑extrusion campaigns on a co‑rotating twin‑screw extruder with 25 mm screw diameter and L/D 40. The colour data were measured on injection‑moulded plaques (ASTM D1003-21) after the copolymer had been devolatilised at −0.095 MPa and 220 °C.
When N‑isopropylmaleimide is incorporated into a continuous bulk acrylonitrile‑styrene process, the feed system must accommodate both the monomer’s latent heat of fusion and its limited solubility in hot styrene at temperatures below 60 °C. The crystalline solid melts at 68 °C, and in a 70:30 (w/w) styrene‑acrylonitrile mixture the saturated concentration at 25 °C is only 12 wt%. To prevent recrystallisation in transfer lines, the monomer is usually pre‑melted in a jacketed vessel held at 75 °C under a dry nitrogen blanket and metered through a gear pump into a static mixer where it is combined with the pre‑heated comonomer stream at 80 °C. Line tracing must maintain a temperature of 72–78 °C over the entire length because excursions below 65 °C cause the maleimide to nucleate on pipe walls, eventually forming blockages that raise the back‑pressure in the feed section of the extruder reactor. In one documented production‑scale installation using a twin‑screw extruder (L/D 44, screw diameter 58 mm) as a continuous polymeriser, the pressure drop across the feed zone increased from 0.8 MPa to 2.1 MPa within 4 h when the trace‑heating setpoint drifted to 62 °C, requiring an unscheduled shutdown and manual cleaning of the injection nozzle. Once dissolved, the isopropyl‑substituted maleimide exhibits a Hansen solubility parameter δd‑δp‑δh reasonably matched to styrene‑acrylonitrile mixtures, so phase separation during bulk polymerisation occurs only at conversions above 70 %, permitting a homogeneous devolatilisation step at 230 °C and 2 kPa absolute pressure with a residence time of 90 s. Residual monomer after that step is typically reduced to <200 ppm as determined by headspace gas chromatography with flame ionisation detection (method adapted from ASTM D4526-20).
When moisture ingress exceeds 0.15 wt% in the as‑received monomer or in the nitrogen blanket, the maleimide ring hydrolyses to the corresponding maleamic acid, which subsequently decarboxylates at processing temperatures, releasing CO2 and generating voids in extruded strands. In a validation run on a 70 mm counter‑rotating twin‑screw devolatilisation line, an increase in the Karl Fischer moisture of the feed from 0.08 % to 0.22 % raised the void count in the resulting pellets from 3 voids/cm³ to 19 voids/cm³ and lowered the notched Izod impact strength (ASTM D256-23, Method A) from 8.2 kJ/m² to 5.6 kJ/m². Pre‑drying of the crystalline monomer is therefore mandated at 40 °C for 4 h under vacuum (≤1 kPa) when the material has been exposed to relative humidity above 60 %. Dry‑air conveying into the feed hopper, with a dew point below −40 °C, is used in lines that operate in tropical climate zones.
The thermal stability of the free monomer places an upper limit on the barrel temperature during melt‑grafting operations. Thermogravimetric analysis at a heating rate of 10 K/min under nitrogen (ASTM E2550-21) shows a 5 % mass loss at ~170 °C and a rapid weight loss above 200 °C attributed to sublimation rather than chemical decomposition, as confirmed by headspace GC‑MS identification of intact N‑isopropylmaleimide in the evolved vapours. This volatility imposes a practical ceiling of 210 °C on the polymer melt temperature at the injection port when a vent port is not present, otherwise localised boiling disturbs the melt seal and entrains oxygen, leading to oxidative cross‑linking and the formation of gels that are detectable as fisheyes in 50 μm blown film. In a 34 mm co‑rotating extruder set to a flat temperature profile of 200–210 °C, a graft‑to‑SAN process achieved a grafting efficiency of 48 % (measured as the ratio of bound maleimide to total fed, after acetone extraction for 24 h) without gel formation; pushing the final zone to 230 °C reduced efficiency to 32 % and produced a 12 % yield of insoluble gel. Hence the processing window is typically defined as 190–210 °C with a maximum residence time of 2 min in the melt phase. The volatility also requires that the extruder be equipped with an atmospheric vent in the feed zone and a vacuum vent (zone 7 of 10) maintained at −0.08 MPa to strip the unreacted monomer.
In contrast, N‑phenylmaleimide, with its 5 % weight‑loss temperature of ~190 °C and a lower vapour pressure at processing temperatures, allows a broader temperature window but introduces phenolic‑type degradation by‑products that shift the colour of the final moulded part to a yellow hue with a yellowness index (ASTM E313-20) typically in the range 12–18. The isopropyl‑substituted derivative, when handled within the stated boundaries, maintains a yellowness index of <5 in injection‑moulded plaques of 2 mm thickness containing 15 wt% maleimide monomer equivalent.
For reactive extrusion grafting of N‑isopropylmaleimide onto polyolefin backbones, the screw configuration must incorporate a melt‑sealing blister element immediately upstream of the monomer injection point to prevent vapour blow‑back toward the feed throat. A typical configuration employs two sets of kneading blocks (forward‑conveying, 30° staggering) separated by a reverse‑flight element that provides a local pressure of 1.5–2.0 MPa. The monomer, pre‑heated to 75 °C and pressurised to 2.5 MPa by a reciprocating pump, is injected through an L‑shaped hollow‑flight nozzle into the melt. In-line near‑infrared probes (wavelength 1600–1800 nm) are used to monitor residual free monomer in the melt stream before the vacuum vent, enabling closed‑loop adjustment of the screw speed to keep the residual below 500 ppm. The difference between N‑isopropylmaleimide and N‑cyclohexylmaleimide in this same configuration is significant: the cyclohexyl derivative, because of its higher melt‑phase solubility (Hildebrand parameter differences of <2 MPa½ versus >4 MPa½ for the isopropyl analogue), yields a grafting efficiency typically 10–15 percentage points higher, yet it imposes a larger Tg depression per unit of incorporated maleimide, making the isopropyl derivative the preferred choice when the primary objective is to raise heat resistance without sacrificing melt flow. Data from a continuous grafting line processing 120 kg/h of polypropylene (MFI 25 g/10 min, ISO 1133-1:2022, 230 °C/2.16 kg) with 1.0 phr N‑isopropylmaleimide and 0.15 phr peroxide showed a Vicat softening point increase from 152 °C to 158 °C (ISO 306:2022, Method A50) and a drop in elongation at break (ISO 527-2:2012, 50 mm/min) from 420 % to 280 %.
