N-Ethyl-2-Aceyl Pyrrole
|
HS Code |
862755 |
| Chemical Formula | C8H11NO2 |
| Molar Mass | 153.18 g/mol |
| Appearance | Solid |
| Color | White to off - white |
| Odor | Characteristic |
| Solubility In Water | Poorly soluble |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, acetone |
| Melting Point | 54 - 56 °C |
| Boiling Point | 265 - 267 °C |
| Density | 1.11 g/cm³ |
As an accredited N-Ethyl-2-Aceyl Pyrrole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram bottle of N - Ethyl - 2 - Acetyl Pyrrole, well - sealed for chemical storage. |
| Shipping | N - Ethyl - 2 - Acetyl Pyrrole is shipped in well - sealed, corrosion - resistant containers. Special handling procedures are followed to prevent spills. It's transported under conditions compliant with chemical shipping regulations to ensure safety. |
| Storage | N - Ethyl - 2 - Acetyl Pyrrole should be stored in a cool, dry, well - ventilated area. Keep it away from sources of ignition and heat. Store in a tightly - sealed container to prevent exposure to air and moisture, which could potentially lead to degradation. Avoid storing near oxidizing agents. Label the storage clearly for easy identification and safety. |
Prior to dough make-up at industrial scale horizontal mixers (stainless steel, **2 000 L** capacity, jacket temperature maintained at **2–4 °C**), N-Ethyl-2-Aceyl Pyrrole is dispersed in a high-melting-point fat fraction—typically partially hydrogenated palm stearin with a slip melting point of **48–52 °C**—to form a protective lipid-encapsulated pre-blend. This pre-blend is folded into the shortening phase at **0.5–2.0 wt%** relative to the total flavour weight, delivering a final concentration of **2–5 ppm** in the baked crumb. During a tunnel oven baking cycle where crumb internal temperature reaches **98–102 °C** for a minimum of **22 min**, the lipid barrier reduces headspace vapour loss quantified by dynamic headspace GC-MS according to **ISO 13299:2016**, preserving the characteristic roasted-nut, cocoa-toned top note. Compliance is anchored to **FEMA GRAS 3147**, **FDA 21 CFR §172.515**, and the Union List of flavourings under **Regulation (EC) No 1334/2008**, Annex I, along with **JECFA 1314** purity specifications. Downstream processing routinely involves spiral cooling conveyors (exit temperature **≤28 °C**) and nitrogen-flushed vertical form-fill-seal packaging to mitigate oxidative scalping of the pyrrole ring. Terminal manufactured goods span laminated croissant, high-ratio cake, sandwich biscuit crème and par-baked bread logs intended for in-store finishing.**Why Do Lecithin-Dependent Viscosity Reductions Influence Aroma Partitioning in Moulded Chocolate?**Addition of N-Ethyl-2-Aceyl Pyrrole to a cocoa butter-based matrix during the dry conching stage—performed in a longitudinal three-shaft conche with a friction-induced temperature steady-state of **51–54 °C**—requires strict control of the shear rate below **1 200 s⁻¹** to prevent localised viscosity collapse and subsequent aroma stripping. Dispersed at **0.05–0.2%** in the chocolate mass (equivalent to **1–3 ppm** in the finished confection), the compound partitions favourably into the continuous lipid phase with a measured logPⁱ of **1.52 ± 0.08**, verified by reverse-phase HPLC under **AOAC 2015.01** conditions. The presence of soy lecithin ( **0.4–0.6%** ) as a viscosity modifier alters surface tension such that the aroma release kinetic constant (k₁₀) shifts by a factor of **1.8** at oral-shear rates, necessitating a dosage recalibration when lecithin source is changed from sunflower to soy due to disparate phospholipid profiles. Regulatory conformance falls under **FDA 21 CFR Part 163** for cacao products and **Directive 2000/36/EC**, with the flavouring substance explicitly listed in the EU permitted substances register. End products include single-origin dark chocolate tablets with **70%** cocoa solids, praline shells deposited into conditioned polycarbonate moulds at **28 °C**, and compound coatings applied via enrobing machines operating at belt speeds of **8–12 m/min**. Operational boundaries mandate that conching duration not exceed **18 hours** when the pyrrole is present, as prolonged exposure to aeration at temperatures above **55 °C** yields a detectable organolepic degradation described as “flat, papery” by panelists trained under **ISO 8586:2012**.Pyrrole Ring Integrity During Ambient Storage of Hypochlorite-Free Heavy-Duty Liquid DetergentsIn the formulation of unbuilt or zeolite-built heavy-duty liquid laundry detergents with a finished pH of **9.2–10.8**, N-Ethyl-2-Aceyl Pyrrole is microencapsulated via an interfacial coacervation process employing melamine-formaldehyde or polyurethane shell walls with a median particle diameter (D₅₀) of **35–55 µm**. The neat aroma chemical is introduced into the base at **0.1–0.5%** of the fragrance composition, yielding a terminal product loading of **0.005–0.02%**. Stability trials conducted in accordance with **IFRA Analytical Method QRA-2** and storage under ICH Q1A climatic conditions ( **40 °C/75% RH** for 12 weeks) demonstrate that free pyrrole concentration in the headspace declines by **≥40%** when the capsule shell integrity is compromised, whereas intact microcapsules maintain > **90%** retentate as verified by py-GC-MS with a pyrolyzer temperature of **350 °C**. Compliance with **IFRA 49th Amendment** and the broader **EU Detergent Regulation (EC) No 648/2004** dictates that the free monomer level in the wash liquor must not exceed the systemic toxicity-derived no-effect level (DNEL) for dermal absorption. Production equipment includes in-line high-shear rotor-stator mixers (tip speed **15–22 m/s**) and volumetric servo-driven dosing pumps calibrated to **±0.5 g** precision. The finished consumer products are liquid detergent units dosed at **45 mL** per wash load, and fabric conditioner sheets where the fragrance is embedded in a surfactant quaternary ammonium matrix on a non-woven polyester substrate. Incompatibility is observed with sodium percarbonate-based oxygen bleach systems: the in-situ generation of perhydroxyl radicals at wash temperatures of **60 °C** causes irreversible pyrrole ring oxidation to form N-ethylmaleimide derivatives, which impart an off-odor described as burnt rubber.When Pyrolytic Transfer Efficiency Becomes the Primary Determinant of Sidestream Aroma ProfileApplication to tobacco filler—whether Virginia-style flue-cured, reconstituted sheet, or expanded stem—relies on a pre-casing cascade where N-Ethyl-2-Aceyl Pyrrole is dissolved in a ternary solvent system of propylene glycol, ethanol, and water (weight ratio **1:8:1**) to a dilution of **0.05–0.2%** and subsequently sprayed through hydraulic atomizing nozzles (orifice diameter **0.3 mm**, pressure **8–12 bar**) onto tumbled leaf lamina to achieve a final mass loading of **10–50 µg/g** on a dry weight basis. During the smoking cycle, the combustion cone temperature ramps from **200 °C** in the condensation zone to approximately **850 °C** at the coal periphery; the pyrrole undergoes thermolytic migration into the sidestream aerosol with a transfer efficiency benchmarked at **12–18%** via filter pad capture followed by solvent desorption and quantitation per **ISO 3308:2012**. Regulatory compliance intersects with **FDA Pre-Market Tobacco Application (PMTA)** data packages for deemed products and **Corcsta Recommended Method No. 84** for pyrolysate characterization. Manufacturing is executed in direct-conditioning rotating cylinders (diameter **1.5 m**, rotational speed **8–14 rpm**) at a leaf throughput of **4 000 kg/h**, with inline NIR moisture sensors maintaining outflow water activity (aw) at **0.48–0.54**. Finished article types include slim-format king-size cigarettes (circumference **17.0 mm**, ventilation **30%** ) and machine-made cigarillos with a homogenized tobacco binder. A documented limitation arises when the pyrrole compound is co-formulated with ammonium hydroxide-based casing agents: the accelerated Maillard-type reaction in the filler generates excessive acrylamide precursors during puffing, breaching voluntary guidelines for toxicant reduction under **ISO 21766:2018**.Extruded dry kibble production on a single-screw or twin-screw cooker-extruder (Wenger TX-57 or similar) with a barrel temperature profile ramping from **80 °C** in the feeding zone to **145 °C** at the die plate imposes a rigorous requirement on volatile aroma retention. To circumvent thermal stripping, N-Ethyl-2-Aceyl Pyrrole is not introduced at the preconditioner but is topically applied via a vacuum infusion coater (VIC) operating at **−0.7 bar gauge** immediately after the dryer, suspended in a warm tallow or hydrolysed poultry fat carrier at **38–42 °C**. The additive rate in the fat coating blend is set at **0.08–0.25%**, corresponding to a finished kibble concentration of **0.5–2 mg/kg**. The Association of American Feed Control Officials (AAFCO) classifies the substance as a Generally Recognized as Safe (GRAS) flavoring for companion animal diets, and within the European Union, it must be listed as “feed flavouring compound” under **Regulation (EC) No 1831/2003**, Annex I, with full traceability through the Rapid Alert System for Food and Feed. Processing equipment further includes a vacuum release valve set to atmospheric pressure across a batch time of **6–9 minutes** to maximize pore penetration, and contra-rotating paddle enrobers that achieve a coating homogeneity with a coefficient of variation below **8%**. Terminal formats encompass small-breed adult kibble with a particle density of **380–420 g/L**, grain-free lentil-based limited-ingredient diets, and oral health biscuits exposed to further high-heat retorting at **121 °C** for **12 min**. In diets fortified with taurine ( **0.1%** ), the pyrrole demonstrates a previously unidentified synergistic effect: the visual browning intensity of the kibble surface increases by **1.8 ΔE*ab** units as measured by a tristimulus colorimeter, requiring a formula adjustment in colour-sensitive white-fish-and-potato recipes to maintain consumer panel acceptability scores above **6.5** on a **9-point** hedonic scale.Density-Adjusted Weighting Agents and Emulsion Droplet Distribution in Cloudy Carbonated BeveragesPreparation of a flavour emulsion containing N-Ethyl-2-Aceyl Pyrrole for a carbonated soft drink requires the compound to be dissolved initially in a terpene-free cold-pressed orange oil base at a ratio of **1:50** before being emulsified into a high-sucrose syrup ( **65°Brix** ) containing ester gum as a primary weighting agent at **9–11%** of the oil phase. The mixture undergoes two-stage high-pressure homogenisation (primary stage **200 bar**, secondary stage **45 bar**, inlet temperature **8 °C** ) to produce a stable O/W emulsion with a median droplet diameter (D₅₀) of **0.8–1.2 µm**. The finished beverage after dilution at a 1-plus-5 syruppackage ratio contains **0.2–0.8 ppm** of the pyrrole, a level that remains below the organoleptic saturation point yet delivers persistent nutty mid-notes perceived by a trained panel using the spectrum descriptive analysis according to **ISO 13299:2016**. Jurisdictional compliance stems from **FEMA GRAS 3147**, **FDA 21 CFR §172.515**, and the specific EU maximum permitted limits for flavouring substances in non-alcoholic flavoured drinks codified in Annex I of **Regulation (EC) No 1334/2008**, where no numerical ceiling is assigned but usage must follow good manufacturing practice. Bottling lines operate at a carbonation level of **3.2–3.6 volumes of CO₂**, and the critical control point is monitored by in-line laser diffraction particle sizing; any aggregation-driven shift of D₉₀ past **3.0 µm** indicates Ostwald ripening, which results in buoyant ring formation at the bottle neck and unacceptable aroma stratification. Finished products accessible at retail include aseptically cold-filled PET bottles ( **500 mL**, vacuum-snift panel monitored at **2.5 mL** expansion), aluminium cans with water-based internal liners, and post-mix syrup bag-in-box formats for fountain dispensation.Reactor Conditions for Sulphydryl-Pyrrole Synergy in Process FlavoursIn a closed jacketed reactor (stainless steel 316L, pressure-rated to **6 bar**) operated at **110 °C** for **55–65 min** with a counter-rotating anchor agitator ( **30 rpm** ), N-Ethyl-2-Aceyl Pyrrole is combined with L-cysteine hydrochloride monohydrate ( **0.8%** ), thiamine hydrochloride ( **0.2%** ), autolysed yeast extract ( **4.5%** ), and d-xylose ( **1.2%** ) in a buffered aqueous medium at pH **6.8–7.2**. The pyrrole loading, typically **0.02–0.10%** of the reaction mass, acts as an auxiliary nitrogenous precursor that diverts the Maillard cascade toward roasted-meat-like pyrazine and thiophenol co-products without forming unacceptably high concentrations of imidazoquinoxaline-type mutagens, as verified by UPLC-MS/MS detection limits below **0.1 µg/kg** for IQ and MeIQx. Quality standards for the resultant process flavour conform to **JECFA Monograph No. 1356** and the **International Organisation of the Flavour Industry (IOFI) Code of Practice**, with the flavour paste subsequently drum-dried on a double-roller drum dryer (surface temperature **135 °C**, film thickness **0.3 mm** ) to a moisture content of **4.5–5.5%**. Downstream blends incorporate the dried paste at **5–12%** into bouillon cube premixes, retort-stable gravy granules, and dehydrated soup sachets. A recognized processing constraint dictates that reactor pH not deviate below **6.5** during heat-up, as even transient acidification promotes protonation of the pyrrole nitrogen and leads to an exothermic condensation with xylose-derived furfural, causing an uncharacteristic sweet-burnt off-flavor quantified as a 2-furfurylpyrrole isomer by SPME-GC × GC-TOFMS.
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N-Ethyl-2-acetyl pyrrole (CAS 39741-41-7, FEMA 3147, FL No. 11.078) functions as a heterocyclic flavor substance deployed to deliver roasted, coffee-like and toasted grain notes in compound flavor formulations. The molecule, an N-substituted derivative of 2-acetylpyrrole, is characterized by a pyrrole ring acylated at the 2-position and ethylated at the nitrogen atom, yielding a molecular formula of C₈H₁₁NO and a molecular weight of 137.18 g/mol. Industrial-grade material typically assays at ≥98% purity by GC–FID, with the principal impurity profile comprising residual 2-acetylpyrrole and positional isomers controlled to less than 0.5% summed. Its introduction into roasted, nutty, and bready top-notes exploits a volatility and polarity window that allows controlled partitioning between the lipid and aqueous phases of finished food matrices. The ethyl group on the nitrogen atom reduces the vapor pressure relative to the parent 2-acetylpyrrole, shifting the perceived retronasal impact toward a longer persistence and softening the harsh, almost fishy edge sometimes associated with the non-alkylated pyrrole. While 2-acetylpyrrole (FEMA 3202) delivers a more aggressive, chip-like roast character, the N-ethyl variant provides a rounder, deeper nut-skin and dark breadcrumb nuance at equivalent dosage, making it the preferred tool for modulating pyrazine-driven roasted profiles without amplifying pyridine-like off-notes.
The substance is typically supplied as a pale yellow to amber liquid with a refractive index nD20 of 1.480–1.485 and a relative density d2020 of 1.000–1.015. Boiling point at standard pressure is reported as 232.9 ± 13.0 °C (estimated via advanced chemistry development software, ACD/Labs), while flash point determined by closed cup method (ASTM D56) falls near 100.5 °C. These values position the ingredient between 2-acetylpyrrole (b.p. ~220 °C) and N-methyl-2-acetylpyrrole (b.p. ~213 °C); the increase in chain length on the nitrogen consistently raises the normal boiling point while lowering the density. Solubility data obtained in common flavor carriers indicate complete miscibility with ethanol, triacetin, propylene glycol, and medium-chain triglycerides at 25 °C, whereas water solubility is below 0.5 g/L. For incoming quality control, the following specifications are applied.
| Parameter | Specification | Test Method |
|---|---|---|
| Purity (GC) | ≥98.0% (sum of isomers) | In-house GC–FID, column DB-WAX, internal standard |
| Refractive index (nD20) | 1.480–1.485 | ISO 280:1998 |
| Relative density (d2020) | 1.000–1.015 | ISO 12185:1996 |
| Acid value (mg KOH/g) | ≤1.0 | ISO 660:2020 |
| Appearance | Pale yellow to amber liquid, free of sediment | Visual inspection at 25 °C |
| Water content | ≤0.2% | Karl Fischer (ISO 760:1978) |
Storage requirements stipulate sealed containers under nitrogen headspace, away from direct light and at temperatures not exceeding 25 °C, to suppress oxidative discoloration and ring-opening pathways catalyzed by trace peroxides. Opened containers should be consumed within 12 weeks when stored under these conditions; published data for longer open-vessel stability are limited.
During thermal processing of baked cereal products, the release kinetics of volatile pyrroles are governed by the partition coefficient between the oil-rich dough matrix and the headspace. The ethyl substituent in N-ethyl-2-acetyl pyrrole increases the log P by approximately 0.4–0.6 units compared to 2-acetylpyrrole, shifting the molecule toward the lipid phase and reducing the initial burst release experienced in the first minutes of chewing. Dynamic headspace dilution analysis (DHDA) conducted with a crushed model biscuit system (25% fat, 4% moisture) and analyzed via SPME-GC–MS revealed that the ethyl derivative displayed a 15–20% lower air-to-matrix partition coefficient at 37 °C than its non-alkylated counterpart. Consequently, flavorists targeting sustained roasted mouthfeel in extended mastication products—such as sandwich cookies, crispbreads, and extruded breakfast cereals—often select the N-ethyl analog to avoid the rapid fade characteristic of more volatile pyrroles. Sensory panels using a paired-comparison forced-choice protocol (following ASTM E679-04 for odor threshold and descriptive analysis) have reported that the roasted-nutty character remains perceivable for an additional 2–4 seconds compared to the 2-acetylpyrrole control at equimolar concentration in a neutral carbohydrate base.
Formulations intended for liquid compound flavors (e.g., bakery emulsions, beverage syrups, dairy flavor bases) commonly dilute N-ethyl-2-acetyl pyrrole to 0.1–1.0% in a carrier solvent prior to dosing into the finished blend. Triacetin and propylene glycol remain the preferred carriers due to low odor contribution and safe regulatory profiles. When using a 100 L jacketed blending vessel with a pitched-blade turbine operating at 200–250 rpm, full dissolution into triacetin at 20–25 °C is typically achieved within 15 minutes. Placing the material directly into aqueous systems requires high-shear dispersion; a Silverson L5M rotor-stator mixer operated at 5,000 rpm for 60 seconds yields a stable submicron emulsion with gum arabic (10% w/w carrier) as emulsifier, enabling homogeneous distribution of the water-insoluble pyrrole in ready-to-drink matrices. Precipitation or ringing-out has been observed when the dose exceeds 25 ppm in aqueous systems without adequate emulsification, leading to localized hotspots and off-note development after as little as 48 hours of storage at 4 °C.
Determination of optimal usage levels in compound flavor bases typically involves dose-response curves constructed across finished food categories. Typical use levels in the final consumer product range from 0.5 ppm to 5 ppm, dependent on the desired roast intensity and the presence of other Maillard-derived flavorings such as pyrazines, thiazoles, and furanones. At levels above 8 ppm in low-fat (<5%) baked matrices, a phenolic, slightly medicinal off-taste can emerge, attributed to trace N-ethylmaleimide-like degradation products formed under local overheating during extrusion where die temperatures exceed 180 °C. In high-fat systems (>20% lipid), the sensory detection threshold rises to approximately 12 ppm thanks to lipophilic sequestration, expanding the process window. Published data for the exact formation kinetics of these trace by-products are limited; however, DSC/TGA screening on production batches shows onset of decomposition shifting from 150 °C in air to 190 °C under nitrogen, underscoring the necessity of inerting during thermal unit operations. When substituting 2-acetylpyrrole with the N-ethyl variant in an existing formulation, a mass-for-mass replacement should not be assumed; sensory panel normalization by odor activity value generally recommends a reduction factor of 0.7–0.9 to account for the increased potency per gram.
The temperature window for extrusion-cooked savory snacks often reaches 160–190 °C in the last zone, conditions that can induce ring fragmentation in non-alkylated pyrroles. N-ethyl-2-acetyl pyrrole exhibits superior thermal resilience relative to 2-acetylpyrrole and N-methyl-2-acetylpyrrole under these conditions, as demonstrated by retained aroma potency after twin-screw extrusion. In a comparative study using a co-rotating twin-screw extruder (L/D 40:1, screw speed 350 rpm, melt temperature 175 °C) with a cereal-based feedstock, GC–MS headspace analysis of the extrudate showed 82% retention of the N-ethyl derivative versus 63% for 2-acetylpyrrole and 71% for the N-methyl analogue, based on internal standard-normalized peak areas. This stability is attributed to the N-ethyl group’s steric shielding of the pyrrole nitrogen against proton abstraction and subsequent ring-opening cascades. Furthermore, the odor profile of the surviving fraction shifted less toward burnt, tarry notes in the N-ethyl case, preserving the target nutty-brown character.
Comparison of key organoleptic and physical attributes across three commercially relevant pyrrole derivatives is summarized below.
| Characteristic | 2-Acetylpyrrole (FEMA 3202) | N-Methyl-2-acetylpyrrole (FEMA 3184) | N-Ethyl-2-acetyl pyrrole (FEMA 3147) |
|---|---|---|---|
| Boiling point (°C, est.) | ~220 | ~213 | ~233 |
| Odor description (dilute) | Pungent roasted, corn chip, slightly fishy | Milder roasted, sweet nutty, medicinal back-note | Deep roasted coffee, toasted breadcrumb, smooth nut skin |
| Typical use level (ppm in food) | 0.5–3 | 0.5–4 | 0.5–5 |
| Flash point (°C, closed cup) | ~95 | ~92 | ~100 |
| Regulatory status (USA) | 21 CFR §172.515 | 21 CFR §172.515 | 21 CFR §172.515 |
| Reported decomposition onset (°C, N₂) | ~140 | ~152 | ~165 |
The divergence in decomposition onset temperatures dictates equipment-specific formulation strategies. Where short-time, high-temperature flash-off is employed (e.g., rotary cone vacuum dryers for powder encapsulation), N-ethyl-2-acetyl pyrrole can withstand jacket temperatures up to 130 °C under reduced pressure without significant loss of active, a margin roughly 10–15 °C wider than that for 2-acetylpyrrole. Pre-blending with maltodextrin carriers of DE 10–15 prior to drying further enhances thermal shielding through vitrification, reducing volatilization losses by 30% relative to a neat feed.
N-Ethyl-2-acetyl pyrrole was affirmed as GRAS by the Flavor and Extract Manufacturers Association (FEMA) in 1981 (Fed. Reg. 46:41242) and is listed for use as a synthetic flavoring substance in the United States under 21 CFR §172.515. European approval is conferred through the Union List of flavoring substances, where it bears FL No. 11.078. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has evaluated the substance (JECFA No. 1512) with no safety concern at current estimated dietary exposure. Compliance with EU Regulation (EC) 1334/2008 requires that the final flavor formulation not exceed the maximum use levels stipulated in Annex II for the targeted food category; for N-ethyl-2-acetyl pyrrole, no specific numerical limits are listed, implying quantum satis application guided by good manufacturing practice. For labeling under Codex Alimentarius, the ingredient is declared as “flavouring (N-ethyl-2-acetylpyrrole)”. REACH registration obligations apply to importers of volumes exceeding 1 metric ton/year, with the relevant substance pre-registered and a registration dossier reportedly completed for the ≥100 t/a band.
Procurement of material with full traceability to a certified flavor intermediate manufacturer is recommended to ensure compliance with residual solvent limits under Directive 2009/32/EC and to avoid cross-contamination with non-food-grade pyrrole precursors. Batch certificates should document absence of primary aromatic amines above 0.01 mg/kg and attest that isomeric purity enables reproducible organoleptic performance. Avoid combining N-ethyl-2-acetyl pyrrole with amine-based additives (e.g., certain caramel coloring classes or ammoniated glycyrrhizin) during intermediate storage phases; the acetyl carbonyl is susceptible to Schiff base adduct formation that progressively reduces flavor yield and can generate unintended colored condensation products visible in clear beverages.
