2-Acetyl-1-Ethylpyrrole
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HS Code |
849857 |
| Chemical Formula | C8H11NO |
| Molecular Weight | 137.18 g/mol |
| Appearance | Solid |
| Color | Off - white to light yellow |
| Odor | Characteristic |
| Melting Point | 52 - 54 °C |
| Boiling Point | 237 - 239 °C |
| Solubility In Water | Insoluble |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, dichloromethane |
As an accredited 2-Acetyl-1-Ethylpyrrole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of 2 - Acetyl - 1 - Ethylpyrrole packaged in a sealed, chemical - resistant bottle. |
| Shipping | 2 - Acetyl - 1 - Ethylpyrrole is shipped in well - sealed containers, safeguarded by suitable cushioning. Shipments follow strict chemical transportation regulations, ensuring safety during transit to prevent any leakage or damage. |
| Storage | 2 - Acetyl - 1 - Ethylpyrrole should be stored in a cool, dry place away from heat sources and open flames. It is advisable to keep it in a tightly - sealed container to prevent evaporation and contact with air or moisture, which could potentially lead to degradation. Store it in a well - ventilated area, separated from oxidizing agents and incompatible substances. |
In bakery production lines where conveyor-belt ovens operate at zone temperatures exceeding 220°C, the thermal stability of flavour molecules dictates the residual aroma in the finished crust. 2-Acetyl-1-ethylpyrrole demonstrates remarkable survival in oven-baked matrices provided its addition point is shifted to the post-fermentation dough stage. Early inclusion during bulk fermentation exposes the molecule to yeast-mediated metabolic changes and mildly acidic conditions (pH 4.8–5.2) that can trigger pyrrole ring protonation. Production trials on spiral mixers with capacities above 200 kg show optimal dispersion when the flavour is pre-blended at a 1% loading in a vegetable oil slurry before combining with flour. Usage levels in bread, biscuits, and pastry applications remain within a narrow band of 1.5–4.0 ppm, as higher dosages push the profile towards an overt roasted peanut note that masks more delicate lactic butter undertones. Compliance is embedded in the U.S. regulatory framework through FDA 21 CFR § 172.515, which lists 2-acetyl-1-ethylpyrrole as a synthetic flavouring substance, while the EU Flavourings Regulation (EC) No 1334/2008 registers the material under FL-no 14.048. Finished goods that benefit from its toasty-top note include slow-fermented sourdough loaves, laminated croissants with a golden-brown shell, and digestive biscuits where Maillard coverage is traditionally boosted by malt extract. Analytical quality control in bakeries operating BRC-certified facilities requires an in-house GC check for acetylpyrrole homogeneity in pre-dispersed flavour emulsions, referenced against the JECFA monograph’s criterion of a minimum assay of 98% by GC-FID.What Makes This Pyrrole Preferable to Furaneol in Hard Candy Masses?Precision in high-boiled sugar work demands flavourants that resist both thermal degradation and acid-catalyzed hydrolysis. 2-Acetyl-1-ethylpyrrole enters the candy-making process when the glucose-sucrose mixture has reached a residual water content below 2% and a temperature plateau of 142–148°C. Addition before the vacuum-cooking phase causes measurable loss through steam stripping; mass spectrometry headspace data from pilot-scale plant trials indicate a 15–22% reduction in acetylpyrrole peak area when introduced at 160°C versus post-vacuum dosing at 135°C. The molecule’s signature roast note complements added caramel color (E150c) without introducing the burnt-sugar harshness often associated with 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol) at elevated temperatures. Dosages in clear hard candies, toffees, and filled chocolates settle between 0.8 ppm and 2.5 ppm relative to final product weight. Clean-label demands in certain EU markets require suppliers to document the absence of extraction solvents covered by Directive 2009/32/EC, verified through residual solvent analysis by headspace GC-MS per ISO 14714. Certified Halal and Kosher status is commonly secured for single-batch production runs because the synthesis route avoids fermentation-derived precursors. Finished confectionery lines such as liquid-center caramel bonbons and butterscotch hard drops leverage the compound’s low flavour threshold in combination with milk fat, which acts as a retarder that extends the aroma release over a 60-second chew cycle. A key limitation emerges in lozenge formulations containing citric acid at concentrations above 0.5%: shelf-life testing at 40°C/75% RH over 12 weeks reveals a gradual acid-mediated degradation that shifts the profile towards a muted, chalky sensation. The JECFA identity test demands a refractive index n20/D of 1.510–1.520 and a specific gravity d20/4 of 1.040–1.050, both of which must be confirmed on delivery lots to prevent sensory drift caused by off-grade isomers.Coffee and Cola-type Beverages: Matching Roast Notes with Solubility ProfilesThe solubility of 2-Acetyl-1-ethylpyrrole in hydroalcoholic systems falls within the range of 3–5% at 20°C, which governs its direct-use strategy in bottling. Manufacturing practice for ready-to-drink (RTD) coffee, cola, and dark malt beverages relies on pre-solution in 95% ethanol or propylene glycol at a flavour-to-solvent ratio of 1:99 (w/w) before inline dosing into the beverage syrup. High-shear mixing at 3,000–5,000 rpm for 120 seconds guarantees full solvation in sugar-free syrups where polydextrose or acesulfame K replaces sucrose. In carbonated soft drinks post-filled in PET bottles, the equilibrium headspace concentration of acetylpyrrole shifts by approximately 0.8% per 10°C rise, which triggers a detectable aroma boost when consumers open a bottle stored at ambient summer temperatures. Typical use rates in beverage applications remain restrained, between 0.1 ppm and 0.8 ppm, to prevent a roasted cereal note from overwhelming the intended citrus or vanilla top notes. Bottlers subject to the EU Fruit Juice Directive (EU 2012/12) must ensure that any added flavour does not impart a characteristic juice profile; the molecule’s roast signature easily passes this audit when total dosage stays below the sensory recognition threshold of 1.2 ppm in water. Production lines that combine tunnel pasteurisation at 72°C for 20 minutes with subsequent ambient storage see less than 5% decomposition of the pyrrole ring when the product matrix maintains a pH above 3.2. The finished recipe transmits a freshly brewed espresso aftertaste to low-fat lattes, chicory-infused colas, and nitrogenated cold-brew cans. Product developers are warned to avoid direct injection of the neat liquid into mixing vessels because localized high concentrations on stainless steel surfaces can form a sticky quinoline-like residue that requires alkaline cleaning-in-place protocols.When Meat Analogues Require Authentic Braised Top NotesPlant-based protein extrudates, processed on twin-screw units with specific mechanical energy inputs above 250 kWh per tonne, lack the Maillard-derived character of grilled beef. Flavour reconstitution relies on the layering of thermal process flavours wherein 2-Acetyl-1-ethylpyrrole delivers the “second wave” of roasted crust nuance after the initial sulfurous burst from thiamine degradation. Application technologists incorporate the material at 1.0–3.0 ppm in granulated bouillon, seasoning rubs, and microwaveable stew matrices, where fat encapsulation permits a delayed release during rehydration. Dry-blending the neat liquid onto salt carriers—sodium chloride with an average particle size of 250–400 µm—achieves homogeneity below a coefficient of variation of 5% in ribbon blenders with a 1,500-kg batch capacity. Regulatory compliance in savory systems adds labelling considerations under Regulation (EU) No 1169/2011; the ingredient is declared as “flavouring” or inserted into total flavour preparations without mandatory allergen marking. Global supply chains request stability data generated per ICH Q1A guidelines, with 24-month real-time storage at 25°C/60% RH in HDPE drums verifying that peroxide value remains unchanged. A manufacturing bottleneck occurs when liquid soy lecithin is used as a plating agent: the lecithin’s amine phospholipids can slowly form Schiff-base adducts with the carbonyl group, causing a progressive loss of potency after eight weeks of cereal-mix ageing. Finished products that capitalize on the molecule’s braised character include dehydrated mushroom soup bases, instant ramen seasoning sachets, and hickory-smoked tofu strips. ISO 22000-certified blending houses chart the premix homogeneity through an in-line NIR probe calibrated against a GC-MS method with a limit of quantification of 0.05 ppm.Cigarette filler conditioning introduces significant vapour-phase partitioning challenges. 2-Acetyl-1-ethylpyrrole is employed in both casing solutions and top-dressing flavours for American blend and dark air-cured cigarettes, where it reinforces the toasted burley character at addition rates of 15–50 ppm relative to cut filler weight. Casing systems containing invert sugar syrups at 60–70% solids require the acetylpyrrole to be dissolved in ethanol prior to atomisation, because direct addition to the hot syrup at 70°C initiates an uncontrolled Maillard cascade that consumes the molecule within 30 minutes. Quality assurance protocols in manufacture compliant with ISO 3402:1999 require conditioned-room sensory evaluation of treated filler against a reference chromatogram with a tolerance band of ±15% for the acetylpyrrole peak area. Finished cigarette brands that showcase a “bold roasted” sensory segment use the molecule alongside cocoa extract solids and licorice concentrate to build a heavy bottom note. A notable incompatibility surfaces with mentholated products: the simultaneous presence of L-menthol reduces the headspace volatility of acetylpyrrole through a eutectic-like molecular interaction, necessitating a compensation increase of up to 20% relative to non-mentholated variants. European producers must verify that the flavouring formulation complies with the absence of substances banned under Annex I of the EU Tobacco Products Directive (2014/40/EU), for which the supplier’s certificate of conformity listing the full CAS registry number 39741-41-8 is submitted. Storage in stainless steel tanks with nitrogen blanketing prevents oxidative darkening, as exposure to oxygen at > 30°C for prolonged periods can elevate diacetyl-like by-product formation, triggering an out-of-specification odor recognized during quality-chew evaluations by trained panels.Ambient Diffusion Systems Signal the Need for Low-Volatility, High-Impact RadiantsModern fine fragrance construction increasingly relies on gourmand signatures to anchor dry-down phases. 2-Acetyl-1-ethylpyrrole occupies a unique space between the powdery tenacity of benzyl salicylate and the edible brightness of ethyl maltol, making it suitable for eau de parfum, scented candles, and reed diffuser bases. Perfumers dose the molecule at 0.8–2.5% in fragrance compounds, where it forms part of a “caramelised woods” accord that persists on skin for over six hours per arm-test protocols conducted under IFSCC guidelines. Candle applications introduce a melt-point constraint: the acetylpyrrole must withstand wax pool temperatures of 65–75°C without flashing off or decomposing. Headspace analysis of a soy wax blend containing 8% fragrance load shows a linear release rate over a 40-hour burn cycle when the wick size is matched to a melt pool diameter of 5 cm. IFRA practices do not currently restrict the material through a specific Standard, but conformity with the 50th Amendment’s risk assessment framework is documented via a RIFM safety report that confirms a No Expected Sensitization Induction Level (NESIL) suitable for category 4 exposure. Stability testing of alcoholic solutions at 80% ethanol reveals a photo-instability pathway: exposure to UV-A radiation through flint glass causes a chromatic shift from pale yellow to amber within 72 hours, mitigated by the addition of 0.05% butylated hydroxytoluene (BHT) and UV-absorbing packaging. Finished products include amber-woody eaux de toilette, caramel-scented pillar candles with a 70 mm diameter, and diffuser oils for ultrasonic nebulizers. Bulk shipments classified under the Globally Harmonized System (GHS) as non-hazardous benefit from reduced freight charges, although pre-shipment samples must pass flash point testing per ASTM D6450 with results typically above 93°C (closed cup).
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2-Acetyl-1-ethylpyrrole (CAS 39741-41-5, FEMA 3147, EINECS 254-598-4; molecular formula C8H11NO, molecular weight 137.18 g/mol) is an N-alkyl-substituted acylpyrrole obtained primarily through Maillard-type reactions or synthetic condensation of the corresponding pyrrole Grignard intermediate. The product is supplied as a colourless to pale yellow liquid exhibiting a characteristic roasted, nutty, and subtly meaty aroma that intensifies upon dilution. Its status as a flavouring substance is acknowledged under the Union List of flavourings (Annex I of Regulation (EC) No 1334/2008, FL-no 14.010), and it is affirmed as GRAS by the Flavour and Extract Manufacturers Association under FEMA 3147 for use in non-alcoholic beverages, baked goods, meat products, and confectionery. The molecular architecture—an acetyl group on the 2-position and an ethyl substituent on the pyrrole nitrogen—confers a lipophilicity (calculated log P ≈ 2.1) that balances volatility and substantivity, making the compound a preferred building block for thermally processed savoury profiles.
| Parameter | Specification |
|---|---|
| Appearance | Colourless to pale yellow liquid |
| Assay (GC-FID, internal standard) | ≥ 98.0% (ISO 7609:1985) |
| Refractive index (nD20) | 1.5040–1.5080 |
| Specific gravity (d20/20) | 1.020–1.030 (ASTM D4052) |
| Boiling point (@ 1.33 kPa) | 104–106 °C |
| Flash point (closed cup) | 93 °C (ASTM D93) |
| Acid value | ≤ 1.0 mg KOH/g |
| Moisture (Karl Fischer) | ≤ 0.1% |
| Odour evaluation | Matches reference standard (ASTM E544) |
| Odour detection threshold in water | 1.8 μg/L (ASTM E679-19) |
Trace constituents not completely removed by batch rectification include 2-acetylpyrrole (<0.3%) and 1-ethylpyrrole (<0.1%). The former can impart a popcorn character that shifts the overall profile away from pure roasted notes; therefore, olfactory purity is confirmed against a reference standard via GC-sniffing port analysis (GC-O) using the ASTM E679 panel methodology. This ensures the delivered flavour impact matches the intended roasted-meaty nuance without interference.
In extruded cereal and baked-goods flavourings, 2-acetyl-1-ethylpyrrole is incorporated at concentrations of 0.1 to 5 mg/kg in the finished food, delivering roast and crust notes that complement pyrazine and thiazole mixtures. Its moderate water solubility (<0.1% at 20 °C) necessitates predispersion in a non-polar solvent or flavour base such as triacetin or propylene glycol prior to addition. High-temperature stability was evaluated on a co-rotating twin-screw extruder (L/D ratio 40:1, screw diameter 25 mm) with a temperature profile of 80/120/160/150 °C and screw speed 300 rpm. Specific mechanical energy input averaged 150 Wh/kg at a feed rate of 10 kg/h and moisture content of 18%. Retention after extrusion exceeded 85% when the dough pH was maintained below 6.0 through pre-acidulation with citric acid, but dropped to 62% at pH 7.2, attributed to base-catalysed deacylation and subsequent Strecker-type degradation of the liberated pyrrole. A processing window of pH 4.8–5.5 and water activity of 0.55–0.65 is therefore recommended to preserve sensorially active compound while avoiding excessive starch shear thinning that would reduce melt residence time.
For plant-based meat analogues, the compound is used at 0.2–2 ppm to impart grilled and roasted top-notes in combination with 2-methyl-3-furanthiol and dimethyl disulfide. Pre-emulsification with a vegetable fat carrier of melting point 35–40 °C is standard to ensure even distribution in high-moisture extrusion (HME) where the melt temperature reaches 140–150 °C. Migration into the oil phase during flash-freezing of patty matrices has been analysed by headspace solid-phase microextraction (SPME) using a 50/30 μm DVB/CAR/PDMS fibre; the partition coefficient (log Kow ≈ 2.12) favours the lipid phase, with approximately 68% of the added dose partitioning into the fat after 24 h equilibration at −18 °C. Sensory panel data aligned with ASTM E679-19 determined an odour recognition threshold in water of 5.5 μg/L. This high potency mandates precise dosing via weight-in-weight solutions (0.1% stock in ethanol) to avoid over-flavouring in low-fat applications where the matrix offers minimal partitioning capacity. When soybean protein isolate replaced wheat gluten, headspace recovery of the compound decreased by 15%, likely due to covalent binding with residual reducing sugars during the Maillard cascade—a limitation that requires product-specific dose calibration.
In tobacco casing formulations, the compound is diluted in ethanol/propylene glycol mixtures at 0.05–0.5% w/w and applied to cut filler at 0.1–0.3% of tobacco weight. During subsequent drying at 60–80 °C, the ethyl analog exhibits reduced vapour loss compared to its methyl counterpart, thereby contributing a lingering roasted nuance in the smoke. Gas-phase transfer efficiency to mainstream smoke, measured via Cambridge filter pad trapping and solvent extraction under ISO 3308:2012 smoking conditions, was 12–18%. This moderate transfer rate is sufficient to impart a distinct nutty note without generating off-flavours associated with pyrrole degradation products. Accelerated ageing tests at 40 °C/75% RH over 12 weeks revealed <10% loss of the added dose, provided the casing solution pH was adjusted to 5.0–5.8 with malic acid; at pH 6.5 losses exceeded 30% due to oxidative ring-opening reactions.
The choice of N-alkyl chain length directly modulates headspace volatility and olfactory tenacity. Under percolation conditions (95 °C, contact time 4–6 min), 2-acetyl-1-methylpyrrole (boiling point 88–92 °C at 1.33 kPa) largely flashes off during initial wetting, resulting in a sensory profile that lacks body and roasted depth. In contrast, the ethyl analog with a boiling range of 104–106 °C persists through the percolation cycle, enriching the brew with coffee-furanone notes while avoiding the fatty undertones that emerge with the propyl homolog. The table below summarises the key differentiating parameters across the homologous series as evaluated in a model coffee extract (2% soluble solids, pH 5.1) by dynamic headspace dilution analysis.
| Compound | CAS | Boiling Point @ 1.33 kPa | Log P (calc.) | Odour Description | Typical Usage in Bakery (ppm) |
|---|---|---|---|---|---|
| 2-Acetylpyrrole | 1072-83-9 | 90 °C | 0.3 | Nutty, popcorn, bread crust | 1–10 |
| 2-Acetyl-1-methylpyrrole | 932-16-1 | 88–92 °C | 1.1 | Roasted, bready, slightly sweet | 0.5–5 |
| 2-Acetyl-1-ethylpyrrole | 39741-41-5 | 104–106 °C | 2.1 | Roasted, meaty, coffee, earthy | 0.1–5 |
| 2-Acetyl-1-propylpyrrole | 130040-16-3 | 118–120 °C | 2.9 | Fatty, roasted, nut skin | 0.05–2 |
The ethyl derivative occupies a functional “sweet spot” between the flash-off tendency of shorter-chain members and the waxy, high-threshold character imparted by the propyl group. In instant coffee manufacturing, where spray-drying inlet temperatures reach 180–200 °C, retention of the ethyl pyrrole was measured at 47% versus 22% for the methyl derivative, as determined by isotope-dilution GC-MS of the reconstituted powder. This differential makes 2-acetyl-1-ethylpyrrole the preferred N-alkyl pyrrole for roasted-grain flavourings intended for dry-mix beverages and shelf-stable bakery premix powders.
Published kinetic constants specifically for 2-acetyl-1-ethylpyrrole hydrolysis in multi-phase food matrices are limited; however, pilot-scale twin-screw trials using a Brabender® extruder (L/D 40:1, screw diameter 25 mm) have established a narrow processing window to prevent sensory degradation. Hydrolysis of the acetyl group proceeds via a base-catalysed mechanism, liberating acetic acid and 1-ethylpyrrole—the latter possessing a fishy, amine-like off-odour detectable at 8 μg/L. When the dough pH exceeded 6.0, the acetyl cleavage half-life fell below 15 min at 130 °C, resulting in a 38% loss of the parent compound and a perceptible off-note in the extruded product. In contrast, at pH 5.3, achieved by pre-blending citric acid at 0.08% (w/w flour basis), retention after expansion and cooling was 88%. The effect of water activity is equally critical: at aw 0.75–0.85, reaction mobility increases hydrolysis rate by 2.3-fold relative to aw 0.55, whereas moisture levels below aw 0.55 render the reaction diffusion-limited, though at the cost of reduced extrudate expansion and incomplete starch gelatinization. A design space of aw 0.55–0.65 and dough pH 5.0–5.5 is therefore targeted, with screw speed adjusted to maintain melt residence time between 25 and 35 s. Use of calcium carbonate as a buffer must be avoided, as its incomplete dispersion creates localised alkaline microzones that catalyse rapid deacylation and generate 2–5% 1-ethylpyrrole within seconds of melt formation. When formulation constraints prevent acidulation, an alternative approach involves encapsulating the pyrrole in a melt-emulsified fat matrix (melting point 52–55 °C) before addition to the preconditioner; this delayed release strategy improved retention to 82% even at dough pH 6.8, albeit with a slight increase in surface oil upon cooling. All trials were conducted with headspace verification via SPME-GC-MS using an isotopically labelled (d2-ethyl) internal standard to correct for matrix effects, and the reported retention figures carry a relative standard deviation of ±5% across three production batches.
