Methyl 1-Methylpyrrole-2-Acetate
|
HS Code |
597517 |
| Chemical Formula | C8H11NO2 |
| Molar Mass | 153.18 g/mol |
As an accredited Methyl 1-Methylpyrrole-2-Acetate factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of Methyl 1 - Methylpyrrole - 2 - Acetate packaged in a sealed, labeled bottle. |
| Shipping | Methyl 1 - Methylpyrrole - 2 - Acetate is shipped in well - sealed, corrosion - resistant containers. Compliance with chemical transport regulations is ensured to prevent leakage and ensure safe transit of this chemical. |
| Storage | Methyl 1 - Methylpyrrole - 2 - Acetate should be stored in a cool, dry, well - ventilated area. Keep it away from heat sources, flames, and oxidizing agents. Store in a tightly sealed container to prevent vapor leakage. Due to its potential reactivity, avoid storage near incompatible substances. This helps maintain its stability and reduces safety risks. |
Production-scale manufacturing of pyrrolizine-based non-steroidal anti-inflammatory drugs (NSAIDs) employs methyl 1-methylpyrrole-2-acetate as the strategic C-2 acetic ester side-chain precursor. The molecule participates in a base-catalysed alkylation with α-bromoacetophenone derivatives—typically phenacyl bromide—at a molar ratio of ester to haloketone of 1.00:1.05 under anhydrous conditions in N,N-dimethylformamide at 0–5 °C. Anhydrous potassium carbonate (1.2 equivalents) serves as the acid scavenger; the suspension is agitated in a glass-lined reactor under a nitrogen blanket to exclude atmospheric moisture, which otherwise hydrolyses the halogenated ketone and depresses yield. Reaction progress is monitored by in-process HPLC (C18 column, UV 254 nm), after which the crude 2-(1-methylpyrrol-2-yl)-3-benzoylpropionate intermediate is quenched into ice-water and extracted with dichloromethane. Solvent exchange to glacial acetic acid precedes a cyclodehydration step mediated by concentrated sulfuric acid (96–98%) at a controlled mass temperature not exceeding 15 °C, generating the pyrrolo[1,2-a]pyrrole bicyclic ring characteristic of ketorolac. Quenching into chilled water and adjustment to pH 8.5–9.0 with aqueous sodium hydroxide precipitates the free carboxylic acid, which is recrystallised from isopropanol/water (70:30 v/v) to reduce single impurities below 0.10 area%. The final NSAID complies with the relevant USP monograph only when the starting ester meets a purity of ≥99.5% (GC-FID), with residual methanol below 3000 ppm, tetrahydrofuran below 720 ppm, and 1-methylpyrrole below 0.1%, all quantified by headspace GC-MS in accordance with ICH Q3C. Manufacturing of the ester itself is governed by cGMP under ICH Q7; dedicated stainless-steel equipment is validated for cross-contamination control when the intermediate is also destined for non-NSAID research libraries. A critical kinetic boundary exists: the alkylation temperature must remain between 0 °C and 5 °C—excursions above 8 °C promote O-alkylation of the transient enolate tautomer and generate a difficult-to-purge by-product that co-elutes with the target intermediate on reversed-phase columns, raising purification costs.
Can a Pyrrole Acetate Ester Deliver Self-Doped Conductive Films for Mild Steel Protection?Electropolymerization of methyl 1-methylpyrrole-2-acetate on low-carbon steel (SAE 1008/1010) and indium tin oxide substrates has been systematically investigated as a route to self-doped polypyrrole films that combine intrinsic electronic conductivity with carboxylate side-group passivation. The monomer is dissolved at 0.1 M in anhydrous acetonitrile containing 0.1 M tetrabutylammonium perchlorate as supporting electrolyte, and the solution is deoxygenated by sparging with argon for 20 minutes prior to deposition. A three-electrode cell configuration uses a saturated calomel reference electrode, a platinum gauze counter electrode, and the pre-polished working electrode; cyclic voltammetry performed between -0.6 V and +1.4 V (vs. SCE) at a scan rate of 50 mV·s⁻¹ reveals an irreversible oxidation onset near +1.05 V, attributed to radical-cation formation on the pyrrole ring. The ester substituent lowers the HOMO energy relative to unsubstituted pyrrole, demanding a more anodic potential but yielding films with fewer crosslinks and enhanced chain regularity, confirmed by Raman spectroscopy (IC=C/IC–C ratio approaching 1.3). Film thickness is controlled by the number of voltammetric cycles; 15 cycles typically deposit 1.2–1.8 µm onto mild steel, measured by stylus profilometry. The as-deposited coating, after rinsing in acetonitrile and vacuum drying at 60 °C, exhibits a deep green-black colour and a compact nodular morphology under SEM. Adhesion assessed per ASTM D3359-17 (cross-hatch tape test) scores 4B–5B, provided the substrate is degreased and activated in 10% oxalic acid immediately before deposition. Undoped films undergo cathodic delamination in chloride-rich electrolyte; therefore, post-deposition immersion in 0.05 M sodium salicylate for 30 min is employed to exchange the perchlorate dopant with a larger, corrosion-inhibiting anion. A head-to-head comparison of perchlorate- and salicylate-exchanged films in neutral salt fog per ASTM B117-19 has been reported in a single pilot-plant study; under those conditions scribe protection was prolonged, yet batch-to-batch scatter in delamination onset time exceeded 30% and no statistical model exists to predict service life. Electrochemical impedance magnitude at 0.01 Hz in 3.5% NaCl solution shifts by roughly one decade upon dopant exchange, but the absolute modulus is strongly influenced by local pH at coating defects and dissolved oxygen concentration, making standardised pass/fail criteria elusive. The processing window at pilot scale (roll-to-roll continuous cell with segmented counter electrodes) demands precise control of inter-electrode gap (2.0±0.2 mm) and line speed (0.5 m·min⁻¹) to avoid edge burn from current density variations exceeding 5 mA·cm⁻², which induces over-oxidation and backbone degradation. No in-service exposure to weather exceeding UV index 8 is recommended without a UV-absorbing topcoat, because the ester side-chain undergoes photolysis, releasing methanol and lowering the doping level. Published data on continuous-web processing remains sparse, restricting current deployment to batch components and repair patches where cure-in-place protocols apply.Acidizing Corrosion Inhibition in Downhole Pipeline TreatmentsMethyl 1-methylpyrrole-2-acetate has been subjected to laboratory-scale screening as a heterocyclic corrosion inhibitor for carbon steel (API 5L X65) in hydrochloric acid solutions (15% by weight) simulating matrix acidizing operations at 60–90 °C. Weight-loss coupons prepared per ASTM G1-03 were exposed for 6 hours under stirred conditions (200 rpm) with inhibitor concentrations ranging from 50 to 500 mg·L⁻¹. Electrochemical evaluation following ASTM G59-97 and Tafel extrapolation from potentiodynamic scans (±250 mV vs. OCP, scan rate 0.166 mV·s⁻¹) categorises the compound as a mixed-type inhibitor with a slight anodic predominance, attributed to adsorption of the pyrrole ring and the ester carbonyl onto the iron substrate through π-electron donation and lone-pair interaction. A surface coverage model fitted to the Langmuir isotherm yields an adsorption equilibrium constant of the order of 10³ L·mol⁻¹ at ambient temperature; however, an inflection in the Arrhenius plot above 70 °C signals desorption onset and reduced protection in deep-well environments. Forced hydrolysis experiments in 15% HCl at 90 °C show that parent compound levels fall below 50% of the initial charge within one hour, as tracked by GC peak area attenuation, indicating limited hydrolytic stability in strong hot acid. Commercial adoption is further constrained by the absence of compatibility data with common acidizing additives—mutual solvents and non-emulsifiers that may competitively displace the inhibitor film—and the lack of field trial reports. The product has not been registered under a regional offshore chemical notification scheme such as the OSPAR Commission’s PLONOR list; any overboard discharge would require ecotoxicity testing per OECD 306 and ready biodegradability assessment per OECD 301F before permitting. Current use is confined to ambient-temperature pickling baths where acid concentration remains below 5% and contact time under 2 hours, verifying that the operational envelope sits well outside the high-temperature acidizing window.Formulators targeting roasted, nutty and coffee nuances in both fine fragrance and encapsulated flavour systems have examined methyl 1-methylpyrrole-2-acetate for its characteristic pyrazine-like but softer profile. At 10 ppm in a neutral sucrose syrup (5% sugar), the molecule delivers a warm, slightly oily, toasted hazelnut aroma with a faint earthy undertone, as evaluated by a sensory panel using quantitative descriptive analysis. In compounded coffee flavours for ready-to-drink beverages, the ester is introduced as a 1% solution in propylene glycol and dosed at 0.02–0.15% of the finished flavour; higher levels introduce a bitter, phenolic off-note that synthetic 2,3-pentanedione can partially mask. The compound is not currently listed in the FEMA GRAS inventory nor in the Union List of flavouring substances under Regulation (EC) No 1334/2008; consequently, its use is limited to non-food applications such as household air fresheners, scented candles, and technical olfactory masking agents where compliance is governed by the International Fragrance Association (IFRA) Standards and a manufacturer’s safety assessment. IFRA practice forbids the presence of secondary amine impurities, detectable by GC-NPD, above 50 µg·kg⁻¹ in the neat ester to avoid nitrosation risk during storage in acidic media. The ester is typically stabilized with 100–300 ppm of butylated hydroxytoluene (BHT) to retard peroxidation, since the pyrrole ring is susceptible to singlet oxygen addition that generates non-odorous but colour-intensifying polymers. Encapsulation in modified starch (octenylsuccinate) via spray drying at 180°C inlet air temperature yields a free-flowing powder with 5–8% load and retention efficiency above 85%, verified by solvent extraction and GC-FID. Applications in bleach-containing cleaners must be individually tested; the electron-rich pyrrole ring is oxidised by hypochlorite above pH 9, causing immediate olfactory collapse and the formation of non-volatile chlorinated by-products. No large-scale toxicological database is publicly accessible; dermal sensitisation has not been reported, but the IFRA quantitative risk assessment for dermal absorption requires a margin of exposure exceeding 100 based on a no-observed-adverse-effect level derived from a 90-day oral repeat-dose study in rodents, which to date remains unpublished.When 1-Methylpyrrole-2-carboxaldehyde Feeds the Library Synthesis PipelineWhen a synthetic route to 1-methylpyrrole-2-carboxaldehyde is designed, methyl 1-methylpyrrole-2-acetate serves as a convenient precursor via Vilsmeier-Haack formylation at the α-position of the acetic side-chain, exploiting the ester’s activated methylene group. A solution of phosphorus oxychloride (1.1 equivalents) in dry 1,2-dichloroethane is added dropwise to a mixture of the ester and 1.3 equivalents of N,N-dimethylformamide at 0 °C, generating the Vilsmeier reagent in situ; the temperature is gradually raised to 60 °C over 4 hours, during which the methylene group condenses, and subsequent hydrolysis with aqueous sodium acetate yields the enamino-aldehyde intermediate that re-aromatises to 1-methylpyrrole-2-carboxaldehyde after steam distillation. The distilled aldehyde, with a boiling range of 82–85 °C at 12 mmHg, obtains a purity of 97% (GC) and is directly employed in Knoevenagel condensations with malononitrile to produce pyrrole-based donor-acceptor chromophores for non-linear optical materials. Alternatively, the aldehyde is converted to the corresponding oxime or thiosemicarbazone and screened in medicinal chemistry programs for kinase inhibition. Because the formylation step generates phosphorus-containing aqueous waste, wastewater pretreatment with calcium hydroxide precipitation is mandatory to meet local discharge limits of 0.5 mg·L⁻¹ total phosphorus. The starting ester for this building-block application can be supplied in technical grade (≥95%) rather than pharmaceutical grade, significantly reducing raw material cost for discovery-phase libraries; however, the presence of residual 1-methylpyrrole must still be controlled below 0.5% to prevent competitive formylation at the ring and the simultaneous formation of 1-methylpyrrole-2-carboxaldehyde, which complicates fractional distillation. This application rarely consumes more than kilogram quantities per campaign because of the potency of downstream products in screening assays. |
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| Parameter | Limit | Test Methodology |
|---|---|---|
| Assay (GC, area%) | ≥ 98.0% | In-house SOP GC-047, based on ASTM E2887-22 |
| Water content (KF) | ≤ 0.2% | ASTM E203-16 |
| Colour (APHA) | ≤ 150 | ASTM D1209-05(2019) |
| Refractive index nD20 | 1.4920–1.4950 | ASTM D1218-21 |
| Density (20 °C) | 1.068–1.075 g·mL⁻¹ | ASTM D4052-22 |
Applications in agrochemical discovery frequently exploit the pyrrole-2-acetate motif as a ketol-acid reductoisomerase (KARI) inhibitor precursor. Structure-activity relationship (SAR) libraries prepared via parallel synthesis employ the methyl ester as the common building block because it withstands 96-well plate amidation conditions — HATU, DIPEA in DMF at 22 °C for 16 h — with <2% hydrolysis, while the corresponding 2,2,2-trifluoroethyl ester suffers up to 8% ester cleavage under identical basic conditions.
| Ester | bp (°C / mmHg) | nD²⁰ | Flash point (°C) |
|---|---|---|---|
| Methyl (2-isomer) | 92–94 / 10 | 1.4930 | 101 |
| Ethyl (2-isomer) | 104–106 / 10 | 1.4885 | 109 |
| Isopropyl (2-isomer) | 108–110 / 10 | 1.4840 | 115 |
| Methyl (3-isomer) | 78–80 / 10 | 1.4850 | 92 |
For operation sites employing automated liquid-handling workstations in compound-management laboratories, a pre-filtered (0.2 µm PTFE) grade is offered. This grade passes a particulate cleanliness threshold of ≤25 particles/mL at ≥10 µm, validated by USP <788> Method 1, enabling direct integration into high-throughput synthesis robots without blocking syringe-needle assemblies. The same filtration step reduces endotoxin levels to <0.05 EU·mg⁻¹ when required for medicinal chemistry programs exploring parenteral candidates, tested per Ph. Eur. 2.6.14, Method D.
The catalytically labile N-methyl group renders the compound incompatible with strong Lewis acids at elevated temperatures. In one documented scale-up incident, attempted Grignard reagent formation from the methyl ester with magnesium turnings in THF under reflux initiated an uncontrolled polymerisation that liberated methane and generated a cross-linked black solid within 20 minutes. This pathway is avoided entirely when lithiation strategies are conducted at −78 °C with LDA, followed by quenching into the appropriate electrophile. Users are therefore directed to pre-cool all reactors to ≤−70 °C before introducing organometallic bases, and to verify jacket integrity with a dry-ice/acetone mixture prior to charging the ester.
