Perhydropyrrole
|
HS Code |
686693 |
| Name | Perhydropyrrole |
| Molecular Formula | C5H11N |
| Molar Mass | 85.15 g/mol |
| Appearance | Colorless liquid |
| Odor | Ammonia - like odor |
| Density | 0.819 g/cm³ |
| Boiling Point | 106 - 107 °C |
| Melting Point | -63 °C |
| Solubility In Water | Miscible |
| Flash Point | 18 °C |
| Vapor Pressure | 10 mmHg at 17.5 °C |
| Refractive Index | 1.432 |
As an accredited Perhydropyrrole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Perhydropyrrole in 500 - gram bottles, well - sealed for chemical protection. |
| Shipping | Perhydropyrrole, being a chemical, requires careful shipping. It should be packaged in suitable, tightly - sealed containers. Shipment must comply with hazardous materials regulations, ensuring proper handling to prevent spills and risks during transit. |
| Storage | Perhydropyrrole should be stored in a cool, dry, well - ventilated area away from heat sources and open flames. Keep it in a tightly sealed container to prevent leakage and exposure to air. Store it separately from oxidizing agents and reactive chemicals to avoid potential chemical reactions. Ensure storage facilities comply with safety regulations. |
In flexible molded foam slabstock lines processing conventional polyether polyols, the addition of perhydropyrrole (pyrrolidine) induces a catalytic shift that suppresses the tin-catalyzed gelling reaction in favor of a more linearized blow profile. This secondary amine, dosed at 0.15–0.35 pph relative to the total polyol mass, interacts preferentially with the para-isomer of methylene diphenyl diisocyanate (MDI) to moderate early viscosity build in the cream zone. The effect is measurable as a 12–18% reduction in force-to-crush values within the first 90 seconds post-pour, as recorded on a F.O.M. 7 block testing rig with a 323 cm² indentation foot. Production-scale trials on a Hennecke Novaflex high-pressure metering unit highlight a narrow processing window: exceeding 0.45 pph pushes the foam toward an open-celled structure with air permeability rising beyond 5.0 ft³/min (ISO 4638:1984 Method A), causing a loss of support factor in grades intended for viscoelastic seating. The compound also shifts the isocyanate-water reaction rate enough to require rebalancing of the tin catalyst; operators typically reduce stannous octoate loading by 8–12% when pyrrolidine enters the premix tank to avoid splitting voids.When Secondary Amine Basicity Dictates Cure Kinetics in Epoxy SystemsCycloaliphatic amine cure agents for liquid epoxy resin (LERG) formulations benefit from perhydropyrrole as a reactive accelerator in low-temperature hardener packages, particularly where ambient-cure coatings must reach walk-on hardness at 5°C. The amine hydrogen equivalent weight (AHEW) of this heterocycle allows a stoichiometric replacement of 20–30% of the conventional benzyl alcohol-accelerated polyamide hardener without sacrificing the glass transition onset temperature (Tg₀) as measured by differential scanning calorimetry (ASTM E1356-08, 10°C/min ramp). On a commercial Nordson hot-spray plural-component rig applying a 100% solids primer to grit-blasted steel (ISO 8501-1 Sa 2½), an adduct prepared from pyrrolidine and a standard bisphenol A diglycidyl ether (EEW 190) achieved a thin-film set time of 48 minutes versus 72 minutes for the unaccelerated control at a substrate temperature of 7°C. Formulating chemists note a practical ceiling: the tertiary amine formed in situ during cure generates a strong exotherm, and laminate thicknesses above 3 mm on vertical surfaces exhibit a severe orange-peel defect traced to a momentary viscosity trough of 0.4 Pa·s before gelation, as logged on a Brookfield CAP 2000+ viscometer with a #6 spindle at 900 s⁻¹.A constraint that requires close attention during winter-grade product development is the incompatibility of free pyrrolidine with epoxy novolac resins of phenol-formaldehyde backbone; residual acidity in the novolac accelerates an unwanted homopolymerization of the amine, dropping pot life by 65% and generating a brittle, low-crosslink-density solid with marginal methyl ethyl ketone (MEK) double-rub resistance per ASTM D5402-19. Operators counter this by pre-reacting the pyrrolidine with a monofunctional glycidyl ether to cap the amine into a secondary-only reactive species before its introduction to the main resin component, a step that reduces volatility and eliminates the amine blush that otherwise manifests as a waxy exudate on concrete sealers cured at 85% RH.Quantifying Added Anodic Inhibition in Acidizing Corrosion Inhibitor PackagesPetroleum-well stimulation fluids formulated with 15–28% hydrochloric acid utilize a corrosion inhibitor intensifier based on perhydropyrrole to suppress hydrogen blistering on N-80 and L-80 tubular steels. Dosed at 0.5–2.0 vol% of the total treatment fluid, the compound adsorbs onto the metal surface through the lone pair of the nitrogen atom, forming a chemisorbed monolayer that blocks the cathodic proton recombination sites with a coverage factor exceeding 0.92 as calculated from electrochemical impedance spectroscopy (EIS) scans conducted in an autoclave at 90°C and 3,000 psi. Weight-loss coupon tests per ASTM G31-72 (modified for 6-hour exposure) on quenched-and-tempered Cr-Mo steel reveal a corrosion rate drop from 0.048 lb/ft² for the base inhibitor package to 0.009 lb/ft² when pyrrolidine is added, a 78% reduction that protects threads and seal faces in packer assemblies.The intensifier’s thermal degradation threshold defines the upper limit of its application: above 135°C bottom-hole static temperature, pyrrolidine undergoes a ring-opening hydrolysis that generates 4-aminobutanal, a species that reacts with aldehydes in the aqueous phase to form a sticky polyimine film that fouls the downstream chokes and surface flowlines. In deep gas wells straddling the 140–150°C zone, formulators substitute 35% of the pyrrolidine with an ethoxylated rosin amine to preserve inhibition while mitigating the fouling tendency, as verified by autoclave visual inspection at the conclusion of a 24-hour live-acid hold period.Downhole Demulsifiers: Managing Naphthenate Solids in Mature WellsCrude oils with a total acid number (TAN) above 1.8 mg KOH/g frequently develop rigid interfacial films when commingled with calcium-rich formation brines, and a specialized class of demulsifiers based on alkoxylated perhydropyrrole adducts resolves this bottleneck at the free-water knockout vessel (FWKO). The adduct is synthesized by reacting pyrrolidine with propylene oxide in a 1:4 molar ratio under base catalysis, yielding a poly(oxypropylene) amine with a cloud point of 27°C in distilled water, as determined by ASTM D2024. On a Lease Automatic Custody Transfer (LACT) unit handling a 38°API Napo formation crude in Ecuador’s Oriente Basin, a continuous injection rate of 45 ppm of this adduct into the produced-fluid header reduced the water content in the oil leg from 2.8 vol% to 0.6 vol% and dropped the BS&W below the pipeline specification of 1.0%.The chemical interacts directly with the naphthenate soap at the oil-water interface, protonating the carboxylate group and collapsing the lamellar gel that stabilizes the rag layer. Process surveillance of the interface inside the FWKO via a guided-wave radar probe (VEGA Flex 81) shows the emulsion band thickness compresses from 72 cm to 18 cm within 45 minutes of initiating the pyrrolidine-based treatment. A persistent operational limitation emerges during high-turbulence flow periods through the upstream choke valve: the demulsifier mechanism requires 8–12 minutes of quiescent residence in the vessel to complete film drainage, and production surges that shorten residence time below 5 minutes cause the rag layer to re-form. Published data for this specific alkoxylation ratio under downhole-safety-valve shear conditions is limited; field optimization relies on bottle-test screening conducted on site at the wellhead sample point with graduated 100 mL centrifuge tubes spun at 2,500 rpm for 5 minutes.Bulk Anionic Polymerization Termination with a Defined EndcapLiving anionic polymerization of styrene-butadiene rubbers (SBR) in a cyclohexane solvent requires a precise termination step, and perhydropyrrole serves as a reactive capping agent that introduces a tertiary amine terminus to the chain end. The 1.0:1.05 molar ratio of living chain-end lithium to pyrrolidine ensures quantitative termination within the 15-minute hold period in a continuous polymerization reactor operating at 55°C, as confirmed by gel permeation chromatography (GPC) monitoring of the molecular weight distribution collapse to a polydispersity index (PDI) of 1.02. The resulting amine-terminated SBR demonstrates a 28% improvement in carbon black dispersion as measured by the Payne effect reduction at 100% strain on a Rubber Process Analyzer (RPA 2000, Alpha Technologies) at 100°C and 0.5 Hz.Tread-grade formulations for passenger-car radial tires (PCR) incorporating 80 phr of this amine-capped SBR in the masterbatch achieve a DIN abrasion index of 122 (ISO 4649:2017, Method A) and a rebound resilience of 52% at 60°C (Zwick 5109 pendulum rebound tester), figures that situate the compound in the rolling-resistance band targeted by EU Tyre Label Regulation (EC) 1222/2009 Class B. A critical processing rule for compounding rooms: the amine end groups react with the sulfur cure accelerator N-cyclohexyl-2-benzothiazolesulfenamide (CBS) during two-roll mill mixing at a surface temperature exceeding 70°C, scavenging pre-formed zinc-accelerator complexes and extending scorch time (t₅) beyond 18 minutes at 135°C on a Monsanto MDR 2000. To prevent this kinetic interference, all curative additions are staged into the final (35-second) pass on a cooled mill at 45°C roll-water temperature, a sequencing constraint that limits throughput on older 84-inch mill lines not equipped with individual roll-temperature control circuits.Continuous-Flow Quaternization for Microbiocidal Cooling-Water FormulationsRecirculating cooling-water systems in petrochemical complexes face microbiologically influenced corrosion (MIC) under sulfate-reducing bacteria (SRB) biofilms, and a quaternary ammonium derivative of perhydropyrrole—specifically N-benzyl-N-ethylpyrrolidinium chloride—delivers a 5-log10 reduction in planktonic SRB counts at 12 ppm active concentration within a 60-minute contact time, as enumerated by serial dilution in modified Postgate’s Medium B at 30°C. The synthesis proceeds through a continuous quaternization loop: pyrrolidine is combined with benzyl chloride and ethyl chloride in a 1.0:0.95:2.2 molar feed ratio in an acetonitrile solvent slug, passing through a jacketed tubular reactor (dimensions: 15 m length, 8 mm ID) maintained at 78°C with a 12-minute residence time. The conversion, tracked by ion chromatography for residual chloride, stays above 98.2% at a throughput of 45 kg/day.Field dosing trials on a 12,000 m³/hr induced-draft cooling tower at a Gulf Coast ethylene cracker demonstrate that the quaternary ammonium salt maintains a planktonic count below 10² CFU/mL over a 14-day slug-dosing cycle with a 15 ppm peak residual, provided that the cooling-water pH does not drift above 8.5. At pH 9.2, the active molecule undergoes a Hofmann-type elimination to yield an inactive vinyl-terminated tertiary amine, and the biocide residual decays with a half-life of 4.2 hours at a bulk water temperature of 42°C. This pH sensitivity excludes the product from cycles operated on high-alkalinity makeup water unless the tower is fitted with a sulfuric-acid pH controller capable of maintaining the sump at 7.8 ± 0.2 units, a modification that requires metallurgical upgrades to the blowdown piping to handle the corrosive mild-acid waste stream.Carbon Dioxide Capture: How Amine Humidity Sensitivity Shapes Absorber Column DesignPost-combustion carbon capture on a natural-gas combined cycle (NGCC) flue gas stream containing 4.2 vol% CO₂ exploits the fast carbamate formation kinetics of perhydropyrrole in an aqueous 30 wt% solution. A bench-scale packed column (structured packing: Sulzer Mellapak 250.Y, 1.2 m bed height) operating at a liquid-to-gas ratio of 3.8 kg/kg and an absorber sump temperature of 52°C achieves a CO₂ removal efficiency of 94% with a rich-solvent loading of 0.62 mol CO₂/mol amine, as determined by a headspace gas chromatography method calibrated against sodium carbonate standards. The regeneration energy demand, measured in a stripper reboiler at 120°C with a 0.8 bar overhead pressure, settles at 2.8 GJ/tonne CO₂, a figure that compares against 3.2 GJ/tonne for a monoethanolamine (MEA) baseline under identical heat-integration boundaries.The design parameter that demands specific attention involves the amine’s volatility and hygroscopicity: the vapor-phase concentration of pyrrolidine in the treated flue gas exiting the water-wash section must remain below 0.3 ppmv to meet air-dispersion modeling limits at the stack, and achieving this target requires a two-stage demister with a 0.15 m mesh-pad thickness and a wash-water recirculation rate of 12 L/h per 1,000 Nm³/h of gas flow. A degradation study conducted by sparging the lean solvent with air at 85°C over 1,200 hours identified the formation of N-(4-aminobutyl)pyrrolidine, a dimeric heat-stable salt that accumulates at 0.7 wt%/week if the reclaimer is operated at a slipstream rate of only 1.0% of the circulating inventory. Plant engineers configure the thermal reclaimer to process 3.5% of the lean stream, discarding the non-regenerable residue as a Class II liquid waste stream for co-processing in a cement kiln. |
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Perhydropyrrole, systematically designated pyrrolidine (CAS 123-75-1), is a fully saturated five-membered secondary amine with molecular formula C4H9N and molar mass 71.12 g/mol. The compound is supplied as a colorless, hygroscopic mobile liquid possessing a penetrating ammoniacal odor. Commercial availability spans multiple models distinguished by purity and water content: anhydrous grade (water ≤0.005%), technical grade (minimum 99.0% purity by GC), and pharmaceutical intermediate grade conforming to USP/NF monographs with residual pyrrole capped at <0.1%. Pyrrolidine is manufactured via catalytic hydrogenation of pyrrole over Raney nickel at 150–200°C and 20–50 bar, or through reductive cyclization of butyronitrile; the route strongly influences the profile of nitrogen-containing trace impurities such as N-alkylpyrrolidines. These compositional differences govern suitability for downstream syntheses where catalyst poisoning or off-target alkylation must be avoided.
Pyrrolidine exhibits a dielectric constant of 8.0 at 25°C and a conjugate acid pKa of 11.27 in water, placing it among the more basic secondary amines. Its density is 0.860 g/cm³ (ASTM D4052), with a distillation range of 86–88°C (ASTM D1078) and a flash point (closed cup) of 3°C (ASTM D56). Vapor pressure measures 58 hPa at 20°C, necessitating closed-system handling. The liquid is fully miscible with water, alcohols, and ethers, yet aprotic character is retained, making it a polar solvent for low-temperature lithiations and Grignard additions. In lithiation of aryl halides at −78°C, the amine solvates lithium cations without donating protons, preventing decomposition of reactive organometallics—a role where the higher steric bulk of piperidine reduces coordination efficiency. The following specification matrix summarizes key trade parameters for three established product models:
| Parameter | Technical Grade | Anhydrous Grade | Pharma Intermediate | Test Method |
|---|---|---|---|---|
| Purity (GC, area%) | ≥99.0 | ≥99.5 | ≥99.5 | ASTM D3329 |
| Water (Karl Fischer) | ≤0.1% | ≤0.005% | ≤0.05% | ASTM E203 |
| Color (APHA) | ≤20 | ≤10 | ≤10 | ASTM D1209 |
| Residual Pyrrole | ≤0.2% | ≤0.1% | <0.1% | Internal GC-MS |
| Non-volatile Residue | ≤0.005% | ≤0.002% | ≤0.002% | ASTM D1353 |
Storage in stainless steel (type 316L) or high-density polyethylene is mandated; contact with copper, brass, or aluminum alloys generates greenish discoloration and promotes aldol-type condensation of trace carbonyl impurities that elevate color beyond specification within 72 h at 40°C.
Zinc pyrrolidine dithiocarbamate (ZPDC), prepared in situ from pyrrolidine, carbon disulfide, and zinc oxide, serves as an ultra-accelerator for natural rubber (NR) and styrene-butadiene rubber (SBR) compounds. In a model NR/BR (60/40 phr) truck tread formulation incorporating 2.5 phr sulfur and 1.0 phr ZPDC, the Mooney scorch time MS-t5 at 120°C falls to 18–22 min compared to 32 min for an equimolar charge of zinc diethyldithiocarbamate (ZDEC). Moving die rheometer data (ASTM D5289) at 160°C, 0.5° arc, reveal an induction time Ts2 of 1.2 min and a torque increase ΔM of 1.78 dN·m after 10 min. The heightened vulcanization rate arises from the lower steric encumbrance of the pyrrolidine moiety, which facilitates nucleophilic attack on the sulfur–zinc complex. A processing window of ±4°C is critical: barrel temperatures exceeding 95°C during open-mill mixing initiate premature scorch, while inadequate dispersion below 65°C results in crosslink density gradients detectable through solvent-swelling heterogeneity (ASTM D471, toluene swell ratio >3.5 in under-cured zones). Zinc oxide level must remain above 3.0 phr to buffer acidic decomposition by-products that otherwise catalyze accelerator degradation, leading to reversion evidenced by a torque reduction of >0.4 dN·m within 15 min of cure.
In the synthesis of cefepime dihydrochloride, pyrrolidine functions as a fragment of the quaternary ammonium side chain. Condensation of 7-aminocephalosporanic acid (7-ACA) with a pyrrolidine-derived electrophile is performed at −10 to 0°C in methylene chloride, employing N-methylmorpholine as acid scavenger. Plant-scale batches at 500–1000 kg reactant loading demand pyrrolidine with water content <0.05% (KF) to prevent hydrolysis of the activated acyl intermediate; a water ingress of 0.2% reduces isolated yield by 6–8% and generates amorphous by-products that necessitate hot filtration through 0.5 µm PTFE membrane cartridges. The exotherm is managed via jacketed glass-lined reactors with brine chilling, and excursions above 5°C induce β-lactam ring opening—detected as impurity signals at relative retention times 1.3 and 1.7 by HPLC. Pyrrolidine purity above 99.5% with residual pyrrole capped at <0.1% is enforced; trace pyrrole engages in an irreversible aza-Michael addition to the cephalosporin nucleus, forming sparingly soluble adducts that accrete on reactor baffles, eventually restricting heat transfer and requiring mechanical cleaning after three batch cycles.
When anhydrous pyrrolidine replaces piperidine in continuous-flow reductive amination of benzaldehyde with sodium triacetoxyborohydride, an increase in turnover frequency from 12 h−1 to 17 h−1 is observed at 25°C in a microreactor with 1.0 mm ID PTFE channel and 30 s residence time. The higher nucleophilicity and lower steric demand of pyrrolidine reduce iminium ion formation half-life, allowing quantitative conversion with 1.05 equivalents of amine. However, product N-benzylpyrrolidine exerts a boiling point of 238°C, complicating separation from high-boiling aldol dimers; thus, a wiped-film evaporator operating at 0.5 mbar and jacket temperature 120°C is required to attain 99.8% distillate purity, a step that is energy-intensive relative to the lower-boiling N-benzylpiperidine (249°C but with less dimer contamination). Published data for this specific configuration in 500-tonne/year campaigns is limited, and scale-up consequences for cyclization side-products remain under investigation.
In hydrochloric acid pickling of carbon steel (ASTM A36), 0.1–0.5 wt% pyrrolidine suppresses the uniform corrosion rate from 12.5 mm/y to below 2.0 mm/y as measured by linear polarization resistance (LPR) per ASTM G59; the inhibition mechanism is consistent with adsorption of protonated amine on cathodic sites. Application is constrained by the amine’s high volatility (vapor pressure 58 hPa at 20°C), requiring sealed pickling baths with condenser recovery to maintain inhibitor concentration.
Pyrrolidine reacts with di-n-propylamine and carbonyl sulfide at 80°C under 5 bar COS pressure in a loop reactor to yield N,N-dipropylpyrrolidine-1-carbothioamide, the penultimate intermediate of the thiocarbamate herbicide prosulfocarb. Selectivity toward the desired thiocarbamoyl product exceeds 92% when the pyrrolidine:di-n-propylamine molar ratio is held at 1.05:1 and the COS feed is sparged through a sintered metal distributor with 2 µm pore size. At ratios below 1.02:1, symmetrical urea formation consumes up to 15% of the pyrrolidine charge, generating a viscous residue that fouls the external tubular heat exchanger and raises pressure drop across the recirculation pump by 0.7 bar after 48 h of continuous operation. Unreacted pyrrolidine is recovered overhead in a thin-film rectification column operating at 100 mbar and recycled, but carbonyl sulfide traces (>50 ppm) in the recycle stream provoke amine carbonation and line blockage; an inline molecular sieve trap charged with 3 Å zeolite is therefore installed. Typical recovery exceeds 98% of excess amine.
Distinguishing pyrrolidine from structurally analogous cyclic amines hinges on subtle changes in ring conformation, basicity, and metabolic behavior. The adjacent table compiles critical comparative data for industrial selection:
| Compound | pKa (conj. acid) | Boiling Point (°C) | Water Solubility (g/100 mL) | Flash Point (°C) | Notable Application |
|---|---|---|---|---|---|
| Pyrrolidine | 11.27 | 86–88 | Miscible | 3 | Cephalosporin side chains, ZPDC accelerator |
| Piperidine | 11.22 | 106 | Miscible | 16 | Diphenylmethane-4,4′-diisocyanate modifier |
| Morpholine | 8.36 | 129 | Miscible | 35 | Optical brighteners, rubber antioxidants |
| N-Methylpyrrolidine | 10.28 | 81 | Soluble | −11 | Ethoxylation catalyst |
| Pyrrole | 0.4 | 130 | Slightly (6) | 33 | Conductive polymers |
The higher basicity and nucleophilicity of pyrrolidine relative to piperidine, despite comparable pKa values, is attributable to reduced steric shielding of the lone pair, a factor that influences rates of N-alkylation and aza-Michael additions. In solvent applications, the lower flash point of pyrrolidine limits its use in open heated vats, and its hygroscopicity demands nitrogen-blanketed storage to keep water below 0.1% in moisture-sensitive syntheses. Unlike morpholine, which introduces an ether oxygen and lower thermal stability, pyrrolidine sustains continuous reductive amination conditions at 120°C for 72 h without ring-oxygen-promoted decomposition. When selecting among these heterocycles for a process, the decision matrix often pivots on tolerance for amine odor, with pyrrolidine’s odor threshold reported at 0.02 ppm—substantially lower than piperidine’s 0.7 ppm—which drives stringent closed-ventilation engineering controls.
Pyrrolidine is registered as a full phase-in substance under EU REACH (EC 204-648-7). The 96-h LC50 in rainbow trout (Oncorhynchus mykiss) is reported as 150 mg/L, indicative of moderate aquatic toxicity. Acute dermal LD50 (rabbit) exceeds 2000 mg/kg, and the vapor causes severe eye irritation classified as Category 1 per CLP Regulation (EC) No 1272/2008. Handling protocols demand local exhaust ventilation to maintain 8-hour TWA airborne concentration below 2 ppm, with continuous monitoring via photoionization detectors set to 10.6 eV lamp energy.
