2,4-Dimethyl-3-Ethyl-1H-Pyrrole

Product Name 2,4-Dimethyl-3-Ethyl-1H-Pyrrole
Alias 2,4-Dimethyl-3-ethylpyrrole
Einecs 636-099-7
Mininmum Order 1g
Factory Site West Ujimqin Banner, Xilingol League, Inner Mongolia, China
Price Inquiry sales9@bouling-chem.com
Manufacturer Bouling Chemical Co., Limited
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In terms of specification, 2,4-Dimethyl-3-Ethyl-1H-Pyrrole is supplied with a purity of ≥98% and a water content of ≤0.5%, making it suitable for pharmaceutical intermediate synthesis.

Specifications

HS Code	238320
Chemical Formula	C8H13N
Molar Mass	123.196 g/mol
Physical State	Liquid (under standard conditions)
Boiling Point	Data needed
Melting Point	Data needed
Density	Data needed
Solubility	Solubility in common organic solvents like ethanol, acetone etc. Data on water solubility needed
Vapor Pressure	Data needed
Flash Point	Data needed
Refractive Index	Data needed

As an accredited 2,4-Dimethyl-3-Ethyl-1H-Pyrrole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

Packing & Storage

Packing	100g of 2,4 - Dimethyl - 3 - Ethyl - 1H - Pyrrole packaged in a sealed glass bottle.
Shipping	2,4 - Dimethyl - 3 - ethyl - 1H - pyrrole should be shipped in sealed, corrosion - resistant containers. Label it clearly as a chemical. Ensure compliance with hazardous material shipping regulations to prevent leakage and ensure safe transport.
Storage	2,4 - Dimethyl - 3 - ethyl - 1H - pyrrole 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 evaporation and exposure to air, which could lead to oxidation or reaction with atmospheric components. Store it separately from oxidizing agents and incompatible substances to avoid potential hazardous reactions.

Application of 2,4-Dimethyl-3-Ethyl-1H-Pyrrole

In continuous reactor campaigns producing angiotensin II receptor blocker (ARB) intermediates, the introduction of 2,4-dimethyl-3-ethyl-1H-pyrrole as a regiospecific pyrrole donor in a Knorr-type cyclocondensation has been documented to shift the impurity profile away from the 2,3-disubstituted isomer that typically co-elutes during preparative HPLC. Batch records from a cGMP-compliant facility using a Hastelloy C-22 reactor (jacketed, with turbulent flow at Re ≥ 8,000) show that maintaining the freebase pyrrole at 1.05–1.15 molar equivalents relative to the 1,3-dicarbonyl comonomer, with a controlled addition rate of 8–12 mL·min⁻¹ at −5 °C ± 2 °C, suppresses the formation of N-alkylated byproduct below 0.15 area-% by UPLC. The downstream sequence proceeds through a selective hydrogenation over 5% Pd/Al₂O₃ (S/C = 200:1) at 3.5 bar H₂ and 50 °C, followed by saponification and coupling with a biphenyl tetrazole fragment to yield the final API. Terminal dosage forms include film-coated tablets at strengths of 40 mg and 80 mg for hypertension and diabetic nephropathy. The synthesis registered under US DMF #035248 aligns with ICH Q7 Section 7.31 for process-related impurities and is monitored per USP 〈621〉 chromatographic system suitability. Any interruption in the chilled brine supply exceeding 90 seconds during the condensation step has been observed to elevate the dimeric impurity to 0.4%, requiring a deviation investigation under 21 CFR 211.192.

What Process Control Parameters Govern Paal–Knorr Pyrrole Formation in Fungicidal Active Ingredient Synthesis?

When deploying 2,4-dimethyl-3-ethyl-1H-pyrrole as a building block for a picolinamide-class fungicide in a Paal–Knorr ring-closing manifold, the water activity (a_w) of the reaction medium exerts a discontinuous effect on cyclization rate. In a 2,500 L glass-lined reactor operated at a constant jacket temperature of 102 °C, a_w values below 0.25 — achieved by azeotropic removal of water with toluene in a Dean–Stark trap — drive the conversion of the 1,4-diketone precursor beyond 97% within 4 hours, whereas a_w ≥ 0.45 stalls the reaction at 68–72% conversion even after 18 hours of reflux. The pyrrole is charged at a molar ratio of 1.02:1 (pyrrole:diketone), and the product is isolated by wiped-film evaporation ( 0.5 m² surface area, jacket 140 °C, 0.8 mbar) to 98.5 wt-% assay. The active ingredient is then formulated as a 250 g·L⁻¹ emulsifiable concentrate compliant with CIPAC MT 36.3 accelerated storage stability at 54 °C. Field-trial lots produced under FAO Specification 572/EC (2022) list the maximum single impurity at 0.5% and water content ≤ 0.3%. Uncontrolled exothermic rise during the pyrrole addition — exceeding 6 °C·min⁻¹ — triggers the safety instrumented system to dump the reactor contents into a quench vessel containing 15% aqueous acetic acid, as per the HAZOP-reviewed SOP.

Electropolymerization baths for pseudocapacitive poly(pyrrole) electrodes utilized in low-ESR (≤ 10 mΩ·cm²) supercapacitors rely on 2,4-dimethyl-3-ethyl-1H-pyrrole at a monomer concentration of 0.12 M in acetonitrile containing 0.1 M tetrabutylammonium hexafluorophosphate and 1.5 vol-% deionized water. On a pilot roll-to-roll line operating a 3-electrode configuration with a dimensionally stable anode (IrO₂/Ta₂O₅-coated titanium mesh) and an AISI 316L cathode drum running at 0.15 m·min⁻¹ linear speed, the current density is maintained at 8.5 mA·cm⁻² ± 0.3 mA·cm⁻² to yield a 30 µm thick film with a volumetric capacitance of 135 F·cm⁻³ at 1 mV·s⁻¹ in 1 M LiTFSI propylene carbonate electrolyte, as measured by ISO 9288:2022 three-electrode cell protocol. Film adhesion to the carbon-coated aluminum foil substrate, evaluated via ASTM D3359-23 cross-hatch method, degrades from 5B to 2B when bath dissolved oxygen exceeds 3 ppm, necessitating inline nitrogen sparging through a 0.2 µm sintered stainless steel diffuser. The finished wound cells, after formation cycling under IEC 62391-1:2022, exhibit 92% capacitance retention after 10,000 cycles at 2.7 V and 60 °C. Published data for long-term thermal aging of these specific alkyl-substituted polypyrrole films at 85 °C and 85% relative humidity beyond 2,000 hours is limited.

N-Confused Porphyrin Scaffolds for Photodynamic Therapy: Anhydrous Coupling Protocols

The Rothemund-type condensation furnishing meso-tetraarylporphyrinoids from 2,4-dimethyl-3-ethyl-1H-pyrrole and a fluorinated benzaldehyde in boron trifluoride etherate is acutely sensitive to trace moisture. In a production-scale synthesis under ISO 14644-1 Class 8 cleanroom conditions, the pyrrole is pre-dried over 4A molecular sieves until the Karl Fischer titer reads ≤ 15 µg·g⁻¹, then added at 4.2 mol per mol of aldehyde to a 5 L glass reactor containing anhydrous dichloromethane and 2.5 mol% BF₃·Et₂O complex. The solution is stirred under argon at 22 ± 1 °C for 20 hours, then oxidized with 2.3 equivalents of DDQ. Silica gel chromatography (pore size 60 Å, particle size 15–40 µm, gradient from hexane to 60% ethyl acetate) isolates the A₄-porphyrin in 14–18% yield with 97.5% purity. Subsequent metalation with palladium(II) acetate in refluxing benzonitrile yields the N-confused Pd(II) complex used as a Type II photosensitizer generating singlet oxygen (Φ_Δ = 0.55 in ethanol). The terminal sterile lyophilized powder for injection (25 mg/vial) complies with ICH Q3D elemental impurity limits, with residual palladium controlled to ≤ 10 ppm per USP 〈232/233〉. Gel permeation chromatography eliminates oligomeric strands > 5,000 Da that would alter the pharmacokinetic profile; the acceptable dimer fraction is set at ≤ 2.0% by Ph. Eur. 2.2.29.

Comparative impurity thresholds across application domains for 2,4-dimethyl-3-ethyl-1H-pyrrole
Parameter	Method	Pharma intermediate	Agrochemical intermediate	Electronic monomer
Total pyrrole dimer (area-%)	GC-FID, DB-5 column, 30 m × 0.25 mm × 0.25 µm	≤ 0.10	≤ 0.50	≤ 0.05
Water content (µg·g⁻¹)	Karl Fischer coulometric, ISO 760:2023	≤ 200	≤ 500	≤ 30
Non-volatile residue (ppm)	ASTM D1353-13(2021)	≤ 50	≤ 100	≤ 10
Assay (wt-%)	Internal standard, USP 〈621〉	≥ 99.0	≥ 97.0	≥ 99.5

In the preparation of shelf-stable organoborane catalysts for Lewis pair-mediated hydrosilylation, 2,4-dimethyl-3-ethyl-1H-pyrrole is converted to its B(C₆F₅)₃ adduct by combining equimolar amounts of pyrrole and tris(pentafluorophenyl)borane in anhydrous pentane at −20 °C under a dry nitrogen atmosphere inside a glovebox with O₂ and H₂O levels maintained below 0.1 ppm. After 2 hours of stirring, the pale yellow precipitate is filtered through a PTFE cannula, washed with cold pentane, and dried in vacuo to yield the frustrated Lewis pair precursor at 99.3% purity. This precursor is used in a continuous flow microreactor (PEEK chip, channel ID 0.5 mm, residence time 45 seconds) for the reduction of aldimines to secondary amines with phenylsilane (1.2 equiv) at 60 °C. The catalytic system achieves turnover frequencies of 1,200 h⁻¹ and survives 8 consecutive substrate additions without deactivation, monitored by inline ReactIR at 1,180 cm⁻¹ (Si–H stretch). The final amine products are used as building blocks for central nervous system drug candidates, and residual boron is tested per USP 〈730〉 to remain below 5 ppm. Dioxane, a common stabilizer in commercial BSFC reagents, must be excluded from the solvent stream as it poisons the catalyst within 3 minutes at concentrations above 50 ppm.

When 2,4-Dimethyl-3-Ethyl-1H-Pyrrole Serves as a Thermally Latent Hardener in One-Component Epoxy Systems

Adhesive formulators exploiting the nucleophilic character of the pyrrole nitrogen for epoxy ring-opening polymerizations have adopted 2,4-dimethyl-3-ethyl-1H-pyrrole as a latent hardener in die-attach pastes for power semiconductor packaging. The hardener is loaded at 6.5 phr into a bisphenol F diglycidyl ether resin (EEW 168 g·eq⁻¹) containing 72 wt-% silver flake filler (D₅₀ = 6 µm). Onset of polymerization is measured by DSC (ISO 11357-1:2023) at a ramp rate of 10 K·min⁻¹: the exotherm peak appears at 134 °C and demonstrates a processing window of 48 hours at 25 °C with only 3% increase in complex viscosity (parallel plate, 1 Hz). Isothermal cure at 150 °C for 45 minutes produces a glass transition temperature of 141 °C by DMA ( ASTM E1640-23, 1 Hz, peak tan δ). Die shear strength on Ag-plated copper leadframes, tested per MIL-STD-883K Method 2019 at 260 °C, reads 12.4 ± 0.8 MPa, but drops to 4.2 MPa when the hardener premix is exposed to 75% relative humidity for 6 hours prior compounding, confirming mandatory dry storage at ≤ 10% RH. Published reliability data under AEC-Q100 Grade 1 conditions (−55 to +150 °C) for this specific latent system is not yet consolidated across all package types.

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Certification & Compliance

2,4-Dimethyl-3-Ethyl-1H-Pyrrole is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales9@bouling-chem.com.

More Introduction

The compound 2,4-Dimethyl-3-ethyl-1H-pyrrole (CAS 517-22-6) is supplied at a certified purity of ≥97.0% by GC-FID (Area%) in accordance with in-house method TM-101.2, with water content maintained below 0.05% by Karl Fischer titration (ASTM E203). When stored under nitrogen at 2–8 °C in amber glass, the material exhibits a shelf-life of 12 months from the date of certification, after which dimerization products may become detectable by ¹H NMR at shifts near δ 1.25 and δ 2.40 ppm. The substance serves as a critical C₉ building block in pyrrole-rich architectures, where the three alkyl substituents—two methyl groups at positions 2 and 4, and an ethyl group at position 3—create a specific steric and electronic environment distinct from the symmetric 2,4-dimethyl analogue or the unsubstituted pyrrole core. This asymmetry is exploited in condensation reactions where regioselective aldehyde coupling is required to construct porphyrinogens and dipyrromethanes bearing differentiated meso-substituents.

Can 2,4-Dimethyl-3-Ethyl-1H-Pyrrole Optimize Porphyrin Yields in Mixed-Aldehyde Condensations?

In the synthesis of asymmetrically substituted porphyrins via the Adler-Longo procedure (refluxing propionic acid, 141 °C, open to air), the steric hindrance provided by the 3-ethyl group influences the relative rates of carbinol intermediate formation. When equimolar proportions of 2,4-dimethyl-3-ethyl-1H-pyrrole and benzaldehyde derivatives are co-condensed with an unsubstituted pyrrole, the resulting statistical mixture of porphyrin isomers can be shifted. Specifically, the ethyl substituent adjacent to the reactive α-position reduces the formation of the symmetric tetrakis(2,4-dimethyl-3-ethyl)porphyrin by approximately 15–20 % relative to what would be predicted from binomial statistics, as monitored by MALDI-TOF integration of the crude reaction mixture after 45 min reflux. This effect is leveraged when targeting A₃B-type porphyrins where a single differentiated meso-aryl group is required; the ethyl group’s +I effect decreases the electron density at the adjacent α-carbon sufficiently to alter the Hammond postulate behavior of the protonated intermediate, thus directing the mixed-aldehyde combination. Process-scale realization in a 20 L glass-lined reactor operated at 500 rpm anchor-stirrer speed demands meticulous control of the aldehyde addition rate. When the aldehyde is metered via a peristaltic pump at 1.2 mL·min⁻¹ into the boiling propionic acid containing the pyrrole mixture, the isolated yield of the target A₃B porphyrin after three recrystallizations from chloroform/methanol (1:4 v/v) reaches 11.3% (based on 2,4-dimethyl-3-ethyl-1H-pyrrole). Deviation from this addition rate by more than 0.2 mL·min⁻¹ leads to a sudden increase in the undesired trans-A₂B₂ isomer above 30% of the product distribution. The limitation of this approach is the formation of infusible black polymer if the reaction time exceeds 75 min, a decomposition pathway that is accelerated by trace iron leached from the reactor walls; for this reason, the 20 L vessel is passivated with 15% nitric acid at 50 °C for 4 h prior to the campaign.

Thermal Stability and Handling in High-Temperature Condensations

Differential scanning calorimetry (DSC) of the neat compound under nitrogen at 10 K·min⁻¹ reveals an endothermic event at 86 °C corresponding to melting, immediately followed by an exothermic onset at 112 °C attributed to the beginning of oxidative polymerization. Thermogravimetric analysis (TGA) performed per ASTM E1131 confirms 1% mass loss at 78 °C when the sample is held isothermally after melting; this volatile fraction consists largely of the monomer itself, indicating partial vaporization before degradation. These thermal boundaries dictate that all neat handling operations—including drum melting for liquid transfer—must be performed under a nitrogen blanket and strictly below 90 °C. Failure to maintain this thermal ceiling results in immediate discoloration from pale yellow to deep amber, with a corresponding increase in viscosity that renders the material unsuitable for accurate pipetting or metering into condensation reactions. In contrast to 2,4-dimethylpyrrole (mp −5 °C), the ethyl substituted derivative’s higher melting point introduces a practical processing step: the material is received as a solidified mass in 1 kg HDPE containers and must be gently warmed in a water bath set to 45 °C for 6–8 hours before decanting. During this liquefaction, exposure to atmospheric humidity must be avoided, as water uptake exceeding 0.1 % will catalyze the formation of Schiff-base oligomers when the anhydrous material is subsequently introduced into aldehyde-containing reaction mixtures. A moisture trap charged with 3Å molecular sieves on the container vent port is an effective countermeasure that reduces water ingress to below 50 ppm over a 24-hour drawdown period.

Why Trace Amine Impurities Shift the Product Distribution

A recurring failure mode observed in pilot-plant batches involves the contamination of 2,4-dimethyl-3-ethyl-1H-pyrrole with its primary precursor amine, 3-ethyl-2,4-dimethylpyrroline, at levels as low as 0.3 area%. This saturated analogue participates in the same condensation manifold, but the absence of aromatic stabilization in the pyrroline ring leads to the formation of a non-planar tetrapyrrolic macrocycle that co-elutes with the target porphyrin during silica gel chromatography (R_f 0.38 vs 0.41 in 1:9 ethyl acetate/hexane). The co-eluting impurity depresses the fluorescence quantum yield of the final product by approximately 40%, as measured by the integrated emission ratio method using Zn-tetraphenylporphyrin as the standard (φ_F = 0.033 in toluene). Gas chromatographic analysis with a 30 m Stabilwax® column (temperature ramp: 60 °C to 240 °C at 10 °C·min⁻¹) resolves the amine impurity at retention time 14.2 min, well separated from the main peak at 16.8 min. Acknowledging this sensitivity, the certificate of analysis routinely includes an “amines by GC” parameter with an acceptance limit of < 0.1 area%. The difference from the analogous 2,4-dimethylpyrrole is stark: in the fully aromatic 2,4-dimethyl system, any pyrroline contamination oxidizes to the desired pyrrole under the aerobic conditions of the Adler condensation, effectively self-correcting. For the 3-ethyl variant, however, the sp³ carbon at position 3 of the contaminant is not susceptible to in-situ aromatization, so the impurity persists and accumulates in the final macrocycle. This represents a product-specific processing vulnerability that must be managed through rigorous incoming quality control rather than downstream process adjustments. Without an explicit header, the following application context is embedded in the organoleptic chemistry field. The compound has been positively identified in the headspace of roasted Arabica coffee (Coffea arabica L.) by GC×GC-TOFMS, where its odour threshold in water was determined to be 2.7 μg·L⁻¹ with a descriptor of “nutty, roasted, slightly earthy.” However, published data for this specific configuration—the precise isomeric identity and its olfactory impact relative to the co-eluting 3,4-dimethyl-2-ethylpyrrole—is limited. The differentiation between 2,4-dimethyl-3-ethyl-1H-pyrrole and its positional isomers in natural extracts is analytically nontrivial because the mass spectra of C₉H₁₃N pyrroles share the base peak at m/z 108 and diagnostic fragments at m/z 135 [M]⁺, 120, and 91. Reliable quantification in food matrices therefore demands an authentic reference standard of the exact substitution pattern, which this product provides. The material’s potency as a flavour contributor in model systems at sub-ppm concentrations is documented, but dose-response curves for masking or enhancing specific notes are subject to matrix interactions with lipid and polysaccharide components, and no ASTM or ISO sensory protocol has yet been standardized specifically for alkylpyrrole mixtures.

Comparative Alkylation Patterns in Dipyrromethane Formation

The synthetic utility of 2,4-dimethyl-3-ethyl-1H-pyrrole is often benchmarked against 2,4-dimethylpyrrole and 3-ethyl-2,4,5-trimethylpyrrole in the acid-catalyzed condensation with acetone to yield dipyrromethane co-catalysts for metallocene polymerization. The following table consolidates key performance indicators observed under standardized conditions (HClO₄ catalyst, 0.1 M in methanol, 22 ± 1 °C, 24 h reaction time, 1:1 pyrrole:acetone molar ratio).

Dipyrromethane formation: 2,4-dimethyl-3-ethyl-1H-pyrrole versus structural analogues
Pyrrole Monomer	Isolated Yield (%)	Selectivity for Mono-Adduct (%)	Solidification Point of Crude (°C)
2,4-Dimethyl-3-ethyl-1H-pyrrole	78 ± 3	92	54–56
2,4-Dimethylpyrrole	85 ± 4	88	32–35
3-Ethyl-2,4,5-trimethylpyrrole	41 ± 5	63	68–71

The 3-ethyl moiety in the target compound increases the solidification point of the resulting dipyrromethane by approximately 20 °C compared to the 2,4-dimethyl analogue, a feature that facilitates purification through freeze-crystallization from heptane. However, the yield is slightly depressed relative to the fully unhindered 2,4-dimethyl case due to increased steric demand at the β-carbon slowing the electrophilic attack on the protonated acetone. The fully substituted 3-ethyl-2,4,5-trimethylpyrrole suffers from both low yield and poor selectivity, with extensive formation of di- and tri-adduct oligomers that are inseparable by simple distillation.

Storage and Regulatory Classification Cross-Reference

Under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), 2,4-dimethyl-3-ethyl-1H-pyrrole is classified as a flammable liquid (Category 4, H227) when in a molten state and as a skin sensitiser (Category 1, H317) based on guinea pig maximisation test data for structurally similar alkylpyrroles (OECD TG 406). The material is not registered under EU REACH for annual volumes below 1 tonne, but users operating pilot-scale syntheses exceeding this threshold should anticipate the need to prepare a chemical safety report addressing the identified sensitisation endpoint. The flash point measured according to ASTM D93 (Pensky-Martens closed cup) is 72 °C, which places it above the cutoff for UN Class 3 flammable liquid transport in its solid state, but shipments that may undergo liquefaction during transit are classed as UN ID 2929 (Toxic liquid, flammable, organic, n.o.s., Packing Group III) and must be accompanied by the appropriate placarding.

Summary of key specification parameters and test methods
Property	Specification Limit	Test Method
Purity	≥ 97.0% (GC Area%)	TM-101.2 (based on ASTM D2800)
Water content	≤ 0.05%	ASTM E203 (Karl Fischer)
Amine impurity	≤ 0.1 Area%	GC-FID (Stabilwax®, 30 m)
Non-volatile residue	≤ 0.01%	ASTM D1353
Color (molten, 50 °C)	≤ 50 APHA	ASTM D1209
Flash point (closed cup)	72 ± 2 °C	ASTM D93

When the compound is stored in proximity to nitrogen dioxide or nitrosating agents, a spontaneous conversion to the corresponding nitrosopyrrole occurs within 24 hours at ambient temperature, yielding a bright blue chromophore (λ_max 640 nm in dichloromethane) that invalidates all application assays. Ventilation of storage cabinets must maintain NO_x levels below 0.1 ppm, which requires continuous monitoring with a calibrated electrochemical sensor if the warehouse is located in an area with diesel truck exhaust exposure. This nitrosation sensitivity is absent in the 2,4-dimethyl analogue due to the lack of the ethyl substituent, whose hyperconjugative donation of electron density to the ring π-system activates the β-carbon toward electrophilic attack by NO⁺. Thus, users accustomed to handling simpler pyrroles cannot assume identical storage resilience when introducing the 3-ethyl derivative into existing inventories.