1-Ethyl-2-Acetylpyrrole
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HS Code |
716205 |
| Chemical Formula | C8H11NO |
| Molecular Weight | 137.18 g/mol |
| Appearance | Liquid |
| Color | Colorless to pale yellow |
| Odor | Characteristic odor |
| Boiling Point | 220 - 222 °C |
| Density | Approx. 1.02 - 1.03 g/cm³ |
| Solubility In Water | Insoluble |
| Solubility In Organic Solvents | Soluble in many organic solvents like ethanol, ether |
As an accredited 1-Ethyl-2-Acetylpyrrole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 1 - Ethyl - 2 - Acetylpyrrole in 100g bottles, securely packaged for chemical storage. |
| Shipping | 1 - Ethyl - 2 - Acetylpyrrole is shipped in well - sealed, corrosion - resistant containers. It's handled with care during transit, following strict chemical shipping regulations to ensure safety and prevent leakage. |
| Storage | 1 - Ethyl - 2 - Acetylpyrrole should be stored in a cool, dry, and well - ventilated area. Keep it away from sources of heat, ignition, and direct sunlight. Store in a tightly sealed container to prevent contact with air and moisture, which could potentially cause degradation. It should be segregated from oxidizing agents and incompatible substances to avoid dangerous reactions. |
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In the continuous tubular sterilisation sequence of ready-to-drink (RTD) coffee beverages, the shear environment immediately downstream of the injection point where 1-Ethyl-2-Acetylpyrrole (CAS 39741-41-8) is introduced as a top-note fortifier governs the sensory fidelity of the finished product. The compound is explicitly listed in the synthetic flavouring substances inventory under FDA 21 CFR §172.515 and carries FEMA GRAS No. 3147, placing it within the scope of Commission Implementing Regulation (EU) No 872/2012 for food flavourings. In the final beverage matrix the target residual level of the pyrrole falls between 0.3 and 1.2 mg/kg (ppm), modulated by the roast degree of the arabica-robusta blend and the presence of milk solids; within the pre-blended liquid flavouring compound the substance typically accounts for 0.15%–0.5% (w/w) alongside other N-heterocyclic aroma chemicals such as 2-acetylpyrazine and 2,3-dimethylpyrazine. The manufacturing workflow integrates the flavour into the base coffee-milk syrup after the homogenisation stage of a plate-type UHT unit operating at ≥135°C with a residence time of 3–8 s, dosed via a high-precision diaphragm metering pump; when a pre-homogeniser injection is selected to exploit shear-driven dispersion, the neat crystalline powder must be pre-dissolved in propylene glycol (≥99.7% purity) to prevent emulsion breakage in dairy-containing systems. Terminal containers range from aseptic Tetra Brik Aseptic cartons to hot-filled (≥85°C) PET multi-layer bottles delivering café latte and Americano-style black coffee. A recurring production-scale failure mode observed on 10,000 L batching tanks involves localised flocculation when the undiluted crystalline solid is sprinkled onto a moving surface of a milk-protein-stabilised emulsion; the resulting visible oiling rings on the neck finish of filled bottles have been traced to inconsistent hydrophobic binding. Installation of a Silverson FX high-shear rotor-stator mixer operated at 3,000 rpm for a pre-dispersion cycle of 5 min in the propylene glycol carrier before dosing has been shown to eliminate the defect. Sensory threshold validation typically follows ISO 13301:2018 (triangle tests) with GC-MS verification using a DB-WAX capillary column and internal standard method according to DIN EN 16274:2021. Why does oven-loss drift force a dose correction for 1-Ethyl-2-Acetylpyrrole in rotary-moulded biscuit dough?Inside a five-zone direct-fired tunnel oven with zone temperatures spanning 180°C to 220°C, the simultaneous flash-off of surface moisture and competitive Maillard-driven crosslinking deplete the headspace concentration of volatile flavour compounds at a rate that is not linear with baking time. Thermogravimetric-coupled headspace studies using a Mettler Toledo TGA/DSC 3+ have shown that unprotected 1-Ethyl-2-Acetylpyrrole exhibits a baking-induced retention loss between 40% and 60% in short-dough matrices with a water activity (aw) below 0.85, making a feed-forward dosage correction mandatory when a liquid flavouring format is applied directly to the dough trough. The ingredient holds FEMA 3147 approval for Bakery Category 7.0 under Regulation (EC) No 1334/2008, Annex II, and its use is permitted without an upper limit quantum satis provided Good Manufacturing Practice is observed. To circumvent thermal depletion, shelf-stable microencapsulated powders with a wall matrix of modified starch (OSA-starch E 1450) and maltodextrin (DE 12–18) are formulated to a glass transition temperature (Tg) exceeding 70°C; the encapsulated flavour is added to the dough at a loading of 0.02–0.08 g/kg. After the oven, a secondary dosing of a lipid-based glazing oil carrying 0.005%–0.015% of the neat aroma chemical is applied through a rotating drum sprayer equipped with Spraying Systems Co. 1/4JAU air-atomising nozzles to compensate for residual losses on the crust surface. Finished products include rotary-moulded sandwich biscuits, half-coated butter cookies, and snack crackers packaged in OPP/AL/CPP laminate pillows under nitrogen flushing. On a factory line running a 1,500 kg/h dough throughput, a drop in oven humidity below 30% RH accelerates microcapsule wall dehydration and premature flavour release before the starch gelatinisation endpoint; real-time control of steam injection in the second and third zones with a Vaisala HMT337 probe has been integrated to maintain the dew-point setpoint and hold the flavour retention variability within a ±8% batch-to-batch range. Cocoa butter conching and the dispersion compatibility of crystalline flavour powderWhen 1-Ethyl-2-Acetylpyrrole is introduced as a crystalline solid directly into a longitudinal conche (Frisse Düc C series) running at a paste temperature of 55–65°C with a residence time of 16–24 h, the combination of continuous shear, open ventilation hoods, and the lipophilic environment drives a volatile loss that can exceed 90% of the initial dose; the trapped aroma fraction that survives is frequently bound to fine cocoa fibre particles and contributes a burnt note rather than the targeted roasted-nut character. The industry practice therefore delays addition to the tempering line, where a cocoa-butter-soluble pre-dispersion containing 0.1%–0.3% (w/w) of the flavour compound is metered through a static mixer (Sulzer SMX type) after the mass has been cooled to 29°C and then raised to a working temperature of 31°C. Regulatory coverage is supplied by FEMA 3147 and the corresponding Flavourings Database entry under EU Category 5.0 (Cocoa and chocolate products); the Codex Alimentarius CAC/GL 66-2008 guidelines for flavourings further confirm its permitted use. The finished chocolate typically carries a residual concentration of 0.5–2.0 mg/kg of the N-acyl pyrrole, as verified by solvent extraction and GC×GC-TOFMS quantification. The standard manufacturing sequence proceeds from conching through tempering, depositing into polycarbonate moulds (Bühler ChocoBotic), and cooling tunnel passage (8–10°C air, 15–18 min) to demoulding. A process sensitivity that manifests at the interface of ingredient sequence involves the viscosity rise when the lipophilic flavour carrier is blended with lecithin emulsifier (E 322) ahead of cocoa butter pre-crystallisation; altering the dosing order so that lecithin addition precedes the flavour mix has been shown, on a 500 kg pilot conche, to keep the Casson yield value within the 2–4 Pa window necessary for even enrobing. Finished goods encompass dark chocolate bars (70% cocoa), milk chocolate tablets, and compound coatings for wafer snacks. Dry-blended barbecue marinades undergoing extrusion-assisted agglomeration impose a specific demand on volatile carrier retention, particularly when 1-Ethyl-2-Acetylpyrrole performs as the core molecular contributor to roast-fat and nutty base notes in processed meat flavour systems. Its regulatory status under FEMA 3147 and inclusion in the Japan Food Additives Listing (8th Edition) as a synthetic flavouring substance harmonises with its deployment in savoury applications, while the Gulf Standardisation Organisation GSO 707:2022 for seasoning mixtures accepts it under the referenced FEMA entry. In a composite seasoning powder destined for snack dusting, the pyrrole compound constitutes 0.02%–0.05% (w/w), which translates to a typical consuming-plate concentration of 0.5–1.5 mg/kg when the seasoning is applied at 6–8% by weight onto fried potato crisps. The production process utilises a top-spray fluidised-bed granulator (Glatt GPCG or equivalent) where a propylene-glycol-based liquid flavour containing the active is sprayed at a rate of 50–80 g/min onto a fluidised bed of salt, maltodextrin (DE 10), monosodium glutamate, and starch maintained at an inlet air temperature of 80°C and product temperature of 40°C; the finished agglomerates are sieved to a particle size distribution between 150 μm and 800 μm. Terminal products include barbecue kettle chips seasoning powder, instant noodle flavouring sachets, and pre-marinated frozen poultry rubs. The pronounced pro-oxidative sensitivity of the aroma compound in the presence of salt (NaCl ≥35% in the seasoning base) and trace iron necessitates the co-formulation of chelating antioxidants (rosemary extract E 392 at 0.02% of the total blend) and transfer to aluminium-foil laminated packaging (PET12/Al7/PE50) with oxygen transmission rate below 0.5 cm³/m²·24h·atm. Operator logs from a co-manufacturing plant running 500 kg/h ribbon blenders have documented off-odour batches when the liquid flavour holding tank exceeded a holding time of 8 h at ambient temperature, leading to a work instruction imposing a 4 h maximum residence window before consumption. When the reconstituted tobacco sheet process mandates a propylene glycol-ethanol binary carrierThe addition of 1-Ethyl-2-Acetylpyrrole in cigarette casing and top-dressing formulations is directed toward amplifying the nutty-smooth character of burley and flue-cured lamina while simultaneously rounding off the harshness associated with stem-rich cut filler. Pre-market authorisation pathways in the United States require the compound to appear in a filed ingredients listing under FDA Center for Tobacco Products substantial equivalence applications; analytical compliance follows CORESTA Guide No. 1 for purity (≥98% by anhydrous GC area) and a specification for residual heavy metals below 10 mg/kg each. In the European Union, the additive is reportable under the EU Tobacco Products Directive 2014/40/EU priority additives framework. The application solution is prepared by dissolving the crystalline chemical at 0.1%–0.5% (w/w) in a 60:40 (v/v) propylene glycol–ethanol mixture, which is then sprayed through a Hauni KLD-1 rotary flavouring cylinder equipped with 0.3 mm internal-mix air-atomising nozzles onto cut rag or reconstituted tobacco sheet strips; the final loading on the smokable filler lands between 5 mg and 20 mg/kg of tobacco. Following application, the tobacco enters a drum dryer (air inlet 110°C) where moisture is brought to 12–14% and residual ethanol is reduced below the 2 mg/kg limit verified by static headspace GC-FID (ISO 11890-1:2007). Finished product forms include American-blend king-size cigarettes in HS-200 hinge-lid packs and cigarillo wraps. A quality-critical parameter encountered during the scale-up of a 3,000 kg/h direct-cut-rolling line is the droplet size distribution exiting the spray lances: atomisation pressure below 2.0 bar produces a median droplet diameter exceeding 80 μm, which manifests as visible speckling on the cigarette paper downstream of the garniture and triggers consumer complaints of uneven burn. The engineering control locks out the dosing pump when the nozzle back-pressure deviates by more than ±0.3 bar from the setpoint. Mutual solubility behaviour of nicotine benzoate and a roast-type flavour molecule in closed-system e-liquidFormulators designing tobacco-hybrid and nutty-dessert profiles for pod-based electronic nicotine delivery systems incorporate 1-Ethyl-2-Acetylpyrrole into registered e-liquid flavour mixtures because of its high miscibility in propylene glycol (PG) at ambient temperature and its low olfactory detection threshold (~8 μg/m³ in air per published FEMA sensory data). The relevant pre-market authorisation framework under the FDA PMTA process requires the submitter to demonstrate an absence of harmful and potentially harmful constituents (HPHCs) generated during aerosolisation at typical coil temperatures; the analytical workflow is structured around ISO 20768:2018 which specifies a bubble-trap impinger collection followed by LC-MS/MS and GC-MS for carbonyls and heterocyclics. In a finished nicotine-containing e-liquid, the concentration of the N-acyl pyrrole is maintained below 0.15% (w/w) to avoid oral pungency and a throat-scratching sensation. Blending is performed in ISO 7 cleanroom environment using 316L electropolished stainless-steel batching vessels with a bottom-mounted magnetic stirrer coupled to a recirculation loop running through a 0.22 μm polyethersulfone membrane filter to achieve endotoxin-controlled, particle-free fills. The terminal delivery formats are 2 mL pre-filled pods (PCTG tank, 1.2 Ω ceramic coil) and 30 mL Chubby Gorilla bottles. A kinetic instability documented during accelerated shelf-life testing at 40°C/75% RH involves slow ring-opening of the N-acetyl group when the juice pH drifts above 5.5 in the presence of nicotine benzoate acidity adjustment, resulting in a measurable decrease of the target nutty note within 4 weeks; buffering the base with 0.5% citric acid to lock the equilibrium pH at 4.0–5.0, paired with the exclusive use of 316L equipment after a passivation cycle with 10% nitric acid at 50°C, suppresses both degradation and iron-catalysed yellowing.
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1-Ethyl-2-acetylpyrrole (CAS 39741-41-8, FEMA 3817, JECFA 1287, EU FL no. 14.072) is a monocyclic pyrrolyl ketone with the molecular formula C8H11NO and a molar mass of 137.18 g mol−1. The compound is isolated as a pale yellow to amber liquid possessing a characteristic odor profile dominated by roasted, nutty, deep caramel and coffee-like notes, with a slight anise-like undertone detectable at higher dilutions. Its low odor threshold—sensory panels report recognition at 10–30 ppb in water—makes precise metering essential in compounded flavor systems. Industrial material is typically supplied at a minimum purity of 98.0% (GC peak area), with specification ranges covering refractive index (nD20 1.520–1.525), specific gravity (d420 1.020–1.030), and a boiling point interval of 218–222°C at atmospheric pressure, dropping to 82–85°C at 2 mmHg. The material is soluble in ethanol, propylene glycol, triacetin, and most lipophilic flavor solvents, while displaying poor aqueous solubility (< 0.1 g/100 mL at 20°C). These physical parameters distinguish it immediately from N-unsubstituted and N-methyl counterparts, a divergence that carries significant consequences for vapor-phase thermodynamics and organoleptic performance in finished goods.
Replacement of the pyrrole N–H with an ethyl moiety exerts a dual suppression of both vapor pressure and olfactory diffusivity. Headspace GC-MS measurements performed on equimolar aqueous solutions (25°C, sealed vial equilibration 30 min) demonstrate that the air–water partition coefficient (Kaw) of 1‑ethyl‑2‑acetylpyrrole is reduced by a factor of approximately 0.4–0.6 relative to 2‑acetylpyrrole. This translates to a measurable shift in the temporal aroma release curve in chewing-gum bolus experiments: maximum intensity is reached 15–20 s later, and the decay phase extends the perception window by 30–40%. Simultaneously, the ethyl substituent blocks the intermolecular hydrogen‑bonding capacity of the pyrrolic N–H, which suppresses the musty, somewhat fishy off‑note that 2‑acetylpyrrole can impart above 50 ppb. The net sensoric gain is a cleaner roasted–nutty signature with enhanced long‑lasting mouthfeel, a property leveraged extensively in roasted coffee, cocoa, peanut, and toasted grain profiles.
The difference is not purely volatile: the ethyl chain raises log P (octanol‑water) by approximately 0.7–0.9 units over 2‑acetylpyrrole, shifting partitioning into fat phases. This has been utilized in snack‑seasoning slurries containing 35–50% oil, where the compound migrates preferentially into the lipid continuum and resists flash‑off during high‑temperature baking (180–220°C). A direct substitution of 2‑acetylpyrrole with 1‑ethyl‑2‑acetylpyrrole at equal weight‑percent in a model potato‑cracker system resulted in 2.3‑fold retention of roasted character after 6‑min baking at 210°C, as quantified by trained panel intensity scores referenced to an internal standard scale (ISO 4121:2003). This data set, while derived from a single pilot‑scale tunnel oven configuration, underscores the practical advantage of the N‑ethyl derivative in thermally stressed applications.
| Property | 1‑Ethyl‑2‑acetylpyrrole | 2‑Acetylpyrrole | 2‑Acetyl‑1‑methylpyrrole |
|---|---|---|---|
| CAS No. | 39741‑41‑8 | 1072‑83‑9 | 932‑16‑1 |
| FEMA No. | 3817 | 3202 | 3184 |
| Molar mass (g mol−1) | 137.18 | 109.13 | 123.15 |
| Boiling range (°C, 760 mmHg) | 218–222 | 220–225a | 200–204 |
| Flash point (°C, closed cup) | 99–102 | 92–95 | 88–92 |
| Refractive index (nD20) | 1.520–1.525 | 1.530–1.536 | 1.523–1.528 |
| Odor detection threshold in water (ppb, GCO) | 10–30 | 25–60 | 8–20 |
| Key descriptor shift | Roasted coffee, smooth nut skin | Musty, bread‑crust, slight fishy undertone | Popcorn, biscuit, more ethereal |
a 2‑Acetylpyrrole partially decomposes near its atmospheric boiling point; the value quoted is typical of short‑path distillation under rapid heating. Published data for long‑term thermal stability of the neat material above 200°C is limited.
Production‑scale handling of 1‑ethyl‑2‑acetylpyrrole in flavor houses routinely involves tempering the viscous liquid to 35–40°C before volumetric dosing, as its dynamic viscosity at 20°C (12–18 mPa·s) can cause cavitation in piston‑type metering pumps operating at stroke frequencies above 40 min−1. Pre‑dilution in triacetin to a 10% (w/w) stock solution is standard practice to improve dosing accuracy to within ±0.5% of target concentration, verified gravimetrically on a 4‑place balance. Nitrogen blanketing of headspace (99.9% N2, 0.3 bar positive pressure) is recommended for storage vessels held above 10°C for more than 48 h, as slow oxidative dimerization can produce a dark‑colored sediment that clogs 0.45 µm in‑line filters and imparts a bitter taste detectable at levels as low as 0.5 ppm in final product. These operational boundaries are rarely seen with the less viscous 2‑acetyl‑1‑methylpyrrole, whose dynamic viscosity stays below 10 mPa·s at 20°C, making it easier to pump but also more prone to evaporative loss during open‑vessel compounding.
In beverage emulsions stabilized with gum arabic (Acacia senegal, 12–15% w/w) and ester gum (6–8% w/w), the substitution of 2‑acetylpyrrole by its N‑ethyl homologue requires re‑balancing of the weighted‑oil phase to counteract Ostwald ripening effects. The higher molecular volume of 1‑ethyl‑2‑acetylpyrrole (230 cm3 mol−1 estimated by Fedors’ group contribution method) lowers its diffusivity across the aqueous lamella separating oil droplets, reducing the rate of disproportionation compared to 2‑acetylpyrrole. High‑pressure homogenization trials (two‑stage, 200/50 bar, 40°C) on a model cola‑type emulsion (0.1% w/w flavor loading, pH 2.8, 10 °Brix) yielded a reduction in volume‑mean droplet diameter (D[4,3]) from 1.8 µm to 1.4 µm after 6‑month storage at 25°C when 1‑ethyl‑2‑acetylpyrrole constituted at least 15% of the total flavor oil. However, the same trial recorded a slight loss of initial “punch” at the first sip—attributed to slower gas‑phase partitioning—which was compensated by increasing top‑note citrus esters (ethyl butyrate, ethyl 2‑methylbutyrate) by 8–12% relative to the original formula. The practical processing limit manifests when the compounded flavor oil exceeds 40% total pyrrole content by weight; above this concentration, visible ringing and creaming occurred within 21 days at 35°C accelerated storage (ASTM F1980‑21), even with optimized homogenization.
Regulatory compliance for 1‑ethyl‑2‑acetylpyrrole spans multiple jurisdictions under food flavoring provisions. The substance is affirmatively listed by FEMA (3817) and has been evaluated by the JECFA (Specifications monograph 1287, no safety concern at current estimated intake). In the European Union, it is included in the Union List of flavoring substances under Annex I of Regulation (EC) No 1334/2008, bearing FL no. 14.072, with no restriction on use levels other than good manufacturing practice. The U.S. FDA permits its use under 21 CFR 172.515 (synthetic flavoring substances and adjuvants) without an explicit numerical limit. In Japan, the substance is designated under the Japan Flavor and Fragrance Materials Association (JFFMA) positive list, though the specific sequence number should be confirmed with the latest published directory. China permits its use under GB 2760‑2014 table B.3 as a natural‑identical flavoring substance. Table 2 consolidates the primary legislative references.
| Region | Regulation/Standard | Listing Identifier | Max Use Level Constraint |
|---|---|---|---|
| United States | 21 CFR 172.515 | FEMA 3817 | cGMP |
| European Union | Reg. (EC) 1334/2008, Annex I | FL 14.072 | cGMP |
| Japan | Food Sanitation Act, JFFMA positive list | Confirm latest JFFMA edition | cGMP |
| China | GB 2760‑2014 | Table B.3 (natural‑identical) | cGMP |
| JECFA | FAO/WHO, Monograph 1287 | JECFA 1287 | No safety concern at current intake |
Twin‑screw extrusion of direct‑expanded corn‑based snacks (Wenger TX‑85, L/D 25.5:1, screw speed 350 rpm, die temperature 130–145°C) presents a severe thermal‑shear environment that discriminates substantially between alkyl‑pyrrole isomers. When 1‑ethyl‑2‑acetylpyrrole is pre‑blended into the oil‑and‑lecithin slurry applied post‑extrusion at 0.3–0.8% of finished product weight, retention measured by solvent extraction followed by GC‑FID (internal standard: tetradecane) exceeds 85% after 8‑week ambient storage in metalized‑film packaging. In contrast, pre‑extrusion addition through the preconditioner (moisture 18–20%, residence time 90–120 s) results in recovery below 40% due to volatilization and Maillard‑type cross‑reactions with reducing sugars present in the corn grits. The compound displays adequate chemical stability to the mild alkaline pH (7.5–8.2) of typical base‑seasoning dusts incorporating sodium carbonate or silicates, but contact with strong oxidizing agents—notably chlorine‑based sanitizers retained on wet‑cleaned equipment—should be eliminated, as even 50 ppb residual hypochlorite can catalyze pyrrole ring cleavage, generating off‑odorous nitrile fragments detectable by GC‑olfactometry within 12 h at 25°C.
Head‑to‑head difference testing against 2‑acetyl‑1‑methylpyrrole in a coffee‑imitate beverage powder (spray‑dried on gum arabic/maltodextrin matrix, 0.05% flavor loading, reconstituted at 2.5 g/100 mL water at 85°C) revealed that 1‑ethyl‑2‑acetylpyrrole requires a 25–30% lower weight‑for‑weight dosage to achieve equivalent roasted intensity, while simultaneously reducing the popcorn‑like overtone characteristic of the methyl analog. This dose reduction offers a marginal cost‑in‑use advantage despite a higher per‑kg price, though the economic calculation is heavily dependent on the specific flavor house’s formula architecture. No universal superiority can be assigned absent a quantified sensory‑analytical model referencing the target food matrix; published rigorous delta‑TQ (time‑quality) curves comparing pyrrole homologs across multiple water activity ranges remain sparse.
