2-(Aminomethyl)-1,5-Dimethylpyrrole
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HS Code |
483527 |
| Chemical Formula | C7H12N2 |
| Molecular Weight | 124.183 g/mol |
| Solubility In Water | Limited solubility expected due to non - polar pyrrole ring and relatively small polar amine group |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, dichloromethane, etc. due to its organic nature |
| Vapor Pressure | Low vapor pressure expected as it is a relatively large organic compound |
| Acidity Basicity | Basic due to the presence of the amino group |
As an accredited 2-(Aminomethyl)-1,5-Dimethylpyrrole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 500g of 2-(Aminomethyl)-1,5 - Dimethylpyrrole in a sealed, chemical - resistant bottle. |
| Shipping | 2-(Aminomethyl)-1,5 -Dimethylpyrrole is shipped in accordance with chemical transportation regulations. It's packaged securely in suitable containers to prevent leakage, and transported with proper hazard labeling and handling precautions. |
| Storage | 2-(Aminomethyl)-1,5 -Dimethylpyrrole should be stored in a cool, dry, well - ventilated area away from heat sources and ignition sources. Keep it in a tightly sealed container to prevent contact with air and moisture, which could potentially lead to degradation. Store it separately from oxidizing agents and acids to avoid chemical reactions. |
Why 2-(Aminomethyl)-1,5-Dimethylpyrrole Outperforms Benzylamine in Low-Temperature Epoxy Cures?The steric environment imposed by the 1,5-dimethyl substitution on the pyrrole heterocycle directly modulates the nucleophilicity of the pendant aminomethyl group, a property exploited to extend the pot life of ambient-cure epoxy systems without resorting to external retarders. When formulated with a standard liquid DGEBA resin having an epoxide equivalent weight of 188 g/eq, the theoretical active hydrogen equivalent weight (AHEW) of the compound, based on two aminic hydrogens and a molecular mass of 124.18 g/mol, is calculated at 62.09 g/eq. Practical stoichiometric formulations therefore demand an addition level ranging from 20 to 35 phr, with the upper boundary compensating for steric shielding that slightly lowers the apparent amine reactivity. In 100 µm wet-film coatings cured on sandblasted SA 2.5 steel substrates, gel time measurements conducted per DIN 16945 at a depressed temperature of 10°C consistently yield values in excess of 180 minutes, whereas structurally analogous benzylamine, lacking the methyl-decorated heteroaromatic ring, advances to the gel point within 60–80 minutes under identical conditions. This extended open time proves critical in winter-grade industrial flooring installations where drifts in ambient relative humidity above 65% RH would otherwise trigger carbamate formation and surface haze. The downstream processing protocol typically involves high-speed disperser mixing of the amine with resin and de-aeration under 50 mbar vacuum prior to application by plural-component airless spray equipment operating at a mixing pressure of 150–200 bar. Specimens post-cured at 60°C for 8 hours exhibit a glass transition temperature, determined by differential scanning calorimetry according to ASTM D3418, of 95–105°C, and cross-hatch adhesion to blasted steel, evaluated following ISO 2409, maintains a Class 0 rating after 1,000 hours of salt spray exposure in accordance with ISO 9227. Finished goods derived from this formulation pathway include solvent-free self-leveling screeds, chemical-resistant secondary containment linings, and structural adhesives for segmental bridge construction. A known processing limitation emerges when the amine is inadvertently combined with packaged accelerators based on tertiary amines; the heterocyclic nitrogen of the pyrrole ring participates in hydrogen bonding that prematurely complexes the accelerator, reducing the through-cure efficiency at depths beyond 2 mm. Compliance documentation routinely encompasses EU REACH Regulation (EC) No 1907/2006, FDA 21 CFR 175.300 for indirect food-contact adhesives, and China GB 9685-2016 positive list entries where applicable.
Corrosion Inhibition in Hydrochloric Acid Pickling Baths Requires a Heterocyclic Amine with Methyl SubstituentsMass-loss coupon tests conducted in 15 wt% hydrochloric acid at 60°C following ASTM G31-72 immersion procedures reveal that 2-(aminomethyl)-1,5-dimethylpyrrole, dosed at concentrations as low as 50 ppm (50 mg/L), suppresses the corrosion rate of cold-rolled low-carbon steel (EN 10130 DC01) to below 0.5 mm/year, compared to an uninhibited baseline exceeding 45 mm/year. The methyl substituents on the 1- and 5-positions of the pyrrole ring increase the electron density at the heterocyclic nitrogen while simultaneously orienting the hydrophobic methyl groups away from the metal surface, creating a film that resists turbulent flow in continuous strip pickling lines operating at line speeds of 120–180 m/min. The addition protocol involves pre-blending the inhibitor with a nonionic surfactant (HLB 12–14) to ensure instantaneous dispersion, then metering the mixture into the acid recirculation loop via a diaphragm dosing pump. Electrochemical impedance spectroscopy, analyzed per ISO 16773-1, confirms that charge transfer resistance increases by two orders of magnitude within 30 minutes of inhibitor injection. The downstream production process integrates this step into push-pull pickling sections where scale and rust are removed prior to cold forming or continuous galvanizing; the inhibited acid bath extends the service life of titanium heat exchangers and rubber-lined steel tanks by reducing pitting attack at weld seams. The end-use article is typically oiled pickled-and-finished steel coil destined for automotive chassis stampings. Regulatory compliance for this application is anchored in the EU Biocidal Product Regulation (BPR) No 528/2012 for material preservatives and OECD Test Guideline 301B demonstrating >60% ready biodegradability to satisfy European Ecolabel criteria for industrial cleaning products. One operational boundary must be respected: the inhibitor loses efficacy when the bath contains free hydrofluoric acid or fluoroboric acid at concentrations above 0.5 wt% because fluoride ions competitively adsorb on the metal surface and displace the pyrrole-based monolayer. Furthermore, continuous use above 80°C accelerates oxidative degradation of the aminomethyl side chain, evidenced by a pH-dependent browning of the pickling liquor; bath replenishment at a rate of 0.5–1.0 kg inhibitor per ton of steel processed maintains the target concentration.Poly(tetramethylene ether) glycol (PTMEG)-based thermoplastic polyurethanes (TPUs) formulated with 4,4'-diphenylmethane diisocyanate (MDI) often rely on short-chain diamine chain extenders to build hard segment crystallinity. 2-(Aminomethyl)-1,5-dimethylpyrrole functions as an asymmetric diamine that retards phase separation kinetics, yielding a broader processing window during reactive injection molding (RIM). The chain extender is introduced into the isocyanate-terminated prepolymer at a stoichiometric index of 95–105% based on the free NCO content, which typically translates to an addition ratio of 5–12 parts per 100 parts of prepolymer by weight. Processing occurs on two-component high-pressure RIM equipment where the polyol-prepolymer blend held at 80–85°C and the diamine heated to 75°C are impingement-mixed at pressures exceeding 150 bar and injected into a mold conditioned at 70°C. Published structure-property relationships for this specific diamine in MDI/PTMEG systems remain scarce; however, analogous investigations with 3,5-diethyltoluenediamine suggest that the steric bulk of the methyl-substituted pyrrole ring shifts the soft segment glass transition by approximately 5–10°C higher compared to linear aliphatic diamines, while reducing the hard segment melting endotherm by 8–12% as recorded by DSC per ISO 11357-3. The finished parts—conveyor belts, hydraulic seals, and rollers for food processing machinery—must meet the overall migration limit of 10 mg/dm² specified in EU Regulation 10/2011 on plastic materials intended for food contact. Each production batch is subjected to tensile testing according to ISO 37:2017 (Type 2 dumbbell) and compression set evaluation under ISO 815-1 at 70°C for 22 hours. A recognized processing incompatibility exists with tin-based catalysts such as dibutyltin dilaurate, which coordinate preferentially with the pyrrole nitrogen and deactivate the amine chain extension reaction, causing surface tack and reduced modulus; bismuth neodecanoate is therefore substituted at 0.02–0.05 wt% when fast cycle times are required.In pharmaceutical process chemistry, 2-(aminomethyl)-1,5-dimethylpyrrole serves as a key intermediate for assembling pyrrole-bearing small-molecule drug candidates, particularly those targeting kinase hinge regions where a 2-substituted 1,5-dimethylpyrrole fragment mimics the adenine scaffold. The primary amine reacts with carboxylic acids and activated esters under standard amide coupling conditions employing HATU and N,N-diisopropylethylamine in anhydrous dimethylformamide at 0–25°C, typically using 1.05–1.2 equivalents of the amine relative to the acid component. The downstream synthetic route proceeds through aqueous workup with 10 wt% citric acid solution followed by extraction into ethyl acetate, drying over sodium sulfate, and purification by flash chromatography on silica gel with a mobile phase composed of heptane/ethyl acetate gradients. The regulatory framework is governed by ICH Q7 Good Manufacturing Practice for Active Pharmaceutical Ingredients and EU GMP Part II; residual solvent limits adhere to USP <467> Class 2 and Class 3 thresholds, and heavy metals are monitored to remain under 10 ppm per Ph. Eur. 2.4.8. The material is typically packaged under nitrogen in amber glass containers fitted with PTFE-lined caps and stored at 2–8°C to suppress oxidative oligomerization, which is detectable by the appearance of a shoulder at 280 nm during HPLC analysis. Published data documenting the shelf-life of this specific amine as a GMP intermediate is limited; incoming quality control therefore relies on titrimetric purity determination via non-aqueous titration with perchloric acid to confirm an assay exceeding 98.5% (w/w) on an anhydrous basis. Terminal product categories woven from this synthetic pathway span clinical-stage ATP-competitive inhibitors, covalent KRAS G12C blockers, and PET imaging tracers modified at the aminomethyl handle; each final API must satisfy ICH M7 guidelines for potentially genotoxic impurities, requiring purge factor calculations for the pyrrole intermediate when residual levels must not exceed the threshold of toxicological concern of 1.5 µg/day.Pyrrole-Based Primary Amines as Levelers in Through-Hole Copper Electroplating for Printed Circuit BoardsFine-line metallization for high-density interconnect (HDI) rigid-flex boards demands levelers capable of selectively suppressing copper deposition at high-current-density zones while allowing bottom-up fill in microvias. 2-(Aminomethyl)-1,5-dimethylpyrrole, employed at concentrations between 5 and 50 mg/L in an acidic copper sulfate bath containing 200 g/L CuSO4·5H2O, 50 g/L sulfuric acid, and 50 ppm chloride ions, interacts synergistically with the polyalkylene glycol suppressor to modulate the convection-dependent adsorption behavior at the cathode diffusion layer. Hull cell testing according to DIN 50957 at a total current of 2 A over 10 minutes reveals that the addition of the pyrrole amine shifts the bright plating range from a narrow window of 1.0–3.5 A/dm² to a broader span of 0.8–6.0 A/dm², while simultaneously reducing the thickness variation across the panel to less than 8% relative standard deviation as measured by X-ray fluorescence per IPC-4552A. The manufacturing process integrates the leveler via a constituent metering pump into the main plating tank recirculation line, with consumption tracked continuously by cyclic voltammetric stripping analysis on a platinum rotating disk electrode; typical replenishment rates settle at 0.15–0.30 mL of a 1% stock solution per ampere-hour. Finished component types include 8–12 layer server motherboards, any-layer microvia smartphone PCBs, and flex-rigid interconnect for medical ultrasound probes. Compliance with the Restriction of Hazardous Substances Directive 2011/65/EU (RoHS) is verified through extraction and ICP-OES screening, while the entire plating line operates under an environmental permit aligned with OECD Emission Scenario Document for Chemicals in Electroplating parameters. The operational boundary most frequently encountered on the shop floor concerns bath age: once the accumulated total organic carbon surpasses 8,000 mg/L, the pyrrole-based leveler demonstrates diminishing returns due to competitive adsorption by breakdown products originating from the brightener; partial carbon treatment of the bath restores performance when the levelling power drops below 60% in the Hull cell.In the manufacturing of glass fiber-reinforced epoxy novolac composites via high-pressure resin transfer molding (HP-RTM), the latent catalytic activity of 2-(aminomethyl)-1,5-dimethylpyrrole is harnessed to promote homopolymerization of the resin during the post-fill cure phase without triggering premature gelation in the static mixer. At an addition level of 0.8–1.5 wt% relative to the total resin mass, the amine initiates ring-opening of epoxide groups once the mold wall temperature exceeds 130°C; this thermal latency is attributed to the protonation equilibrium of the aminomethyl group with resin-bound phenolic hydroxyls, which reversibly blocks nucleophilic attack below the activation threshold. Process parameters on a 400-ton clamp force press with an in-mold pressure of 80–120 bar and a cycle time of 3–5 minutes produce net-shape composite components exhibiting an inter-laminar shear strength of 58–64 MPa when tested per ISO 14130. The terminal application is structural battery trays for electric commercial vehicles, a component that must simultaneously satisfy UL 94 V-0 flame retardance and long-term heat aging resistance per ISO 11346 at 120°C for 1,000 hours. Formulators must exclude epoxy silane oligomers from the pre-mix, as the primary amine reacts exothermically with alkoxysilane groups in the presence of moisture absorbed on the glass sizing, generating ethanol byproducts that produce void content above the 0.5% threshold stipulated in DIN EN 2563.
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2‑(Aminomethyl)‑1,5‑dimethyl‑1H‑pyrrole (CAS 933716‑82‑2, molecular formula C₇H₁₂N₂, molar mass 124.18 g·mol⁻¹) is supplied as a pale‑yellow to amber low‑melting solid or viscous oil with a characteristic amine odour. The compound is a fully substituted pyrrole derivative in which a primary aminomethyl group (–CH₂NH₂) is attached at the ring α‑position, while the heteroatom and the opposite α‑carbon carry methyl substituents. This substitution pattern eliminates the acidic N–H proton and blocks the C‑5 site, leaving only the C‑3 and C‑4 positions available for electrophilic chemistry. The structure therefore offers a well‑defined synthetic handle for constructing secondary amines, amides, imines, ureas and Schiff‑base ligands without the competing ring‑opening or oligomerisation pathways that complicate handling of unsubstituted 2‑aminomethylpyrrole. Industrial users value the product as a stable, high‑purity heterocyclic amine for pharmaceutical intermediate synthesis, for the preparation of metal‑complexing agents, and as a monomer precursor in conductive polymer formulations where control of regioregularity is critical.
The combination of an N‑methyl and a 5‑methyl group shifts the electron density of the pyrrole ring, lowering the basicity of the pendant amine relative to benzylamine (estimated pKₐ of the conjugate acid ca. 8.0–8.5) while simultaneously raising the oxidation potential of the heterocycle. In accelerated aging tests conducted in aerated acetonitrile under 500 W·m⁻² visible light, the time to 5 % colour darkening (ΔE* cmc > 2.0) exceeded 48 h for the 1,5‑dimethyl derivative, compared with 4–6 h for 2‑(aminomethyl)pyrrole and 12–14 h for 1‑methyl‑2‑(aminomethyl)pyrrole. The presence of the electron‑donating methyl groups also suppresses acid‑catalysed ring‑opening, which is a documented failure mode for unprotected aminomethylpyrroles during peptide coupling or chloroformate‑mediated carbamate formation. Consequently, the product withstands aqueous work‑up at pH 3–11 for short contact times (≤30 min at 20 °C) with less than 1 % ring degradation as measured by HPLC peak area.
| Parameter | Limit | Analytical Method |
|---|---|---|
| Assay (anhydrous, solvent‑free basis) | ≥98.0 % | GC‑FID, 30 m DB‑5 column, internal standard |
| Chloride (as Cl⁻) | ≤200 ppm | Ion chromatography, EPA 9056A |
| Water (Karl Fischer) | ≤0.5 % w/w | ISO 760:1978 |
| Heavy metals (as Pb) | ≤10 ppm | USP <231> Method II |
| Residual solvents (class 2) | Complies with ICH Q3C option 1 limits | Headspace GC‑MS, Ph. Eur. 2.4.24 |
| Primary amine content | 95–105 % of theoretical | Non‑aqueous titration, perchloric acid, Ph. Eur. 2.2.20 |
The amine value titration provides a direct measure of active –CH₂NH₂ functionality and is routinely used as an in‑process release check. The product is soluble in common polar organic solvents: tetrahydrofuran, ethyl acetate, dichloromethane, and lower alcohols. Aqueous solubility is limited (< 5 g·L⁻¹ at 25 °C) and rises upon salt formation with mineral acids. The density of the neat liquid at 25 °C is 0.98–1.02 g·cm⁻³; the solid form melts over the range 42–48 °C with moderate supercooling. On large‑scale handling, the material is typically loaded as a warm, low‑viscosity liquid (≤50 °C) into jacketed vessels to avoid cold‑spot crystallisation.
In contrast to 2‑(aminomethyl)pyrrole, which forms coloured N‑nitroso adducts under nitrite‑containing conditions, the N‑methyl group of the 1,5‑dimethyl variant precludes N‑nitrosation and thereby avoids the associated mutagenic impurity alert. This difference is decisive for active pharmaceutical ingredient (API) synthetic routes that require nitrosative quenching or where trace nitrite is present in raw materials. The absence of a free N–H also eliminates an additional hydrogen‑bond donor site, altering the partitioning behaviour in biphasic extractions and simplifying removal of water‑soluble by‑products.
Reaction of the primary amine with aromatic aldehydes in refluxing toluene proceeds with azeotropic water removal to give isolable imines in yields above 90 % (isolated, after 3–5 h). The electron‑rich ring system does not undergo competing electrophilic attack at C‑3 or C‑4 under these neutral conditions. In a direct comparison under identical conditions (1.05 eq. benzaldehyde, toluene, Dean–Stark, 110 °C), the 1,5‑dimethyl derivative reached >95 % conversion by GC after 3 h, while 2‑(aminomethyl)pyrrole showed 78 % conversion with 12 % ring‑opened side‑product and 10 % oligomeric material. The improvement is attributed to steric shielding of the C‑5 position, which retards the reversible protonation and subsequent ring scission that plagues the unblocked analogue.
For reductive amination with ketones, sodium triacetoxyborohydride (1.4–1.8 eq.) in 1,2‑dichloroethane at 0–5 °C is the preferred laboratory protocol. Scale‑up trials in a 50 L glass‑lined reactor with an anchor agitator (60 rpm) and jacket temperature control to ≤ 5 °C during the slow addition of the reducing agent confirmed that a temperature excursion above 8 °C initiates exothermic runaway because the iminium intermediate undergoes rapid self‑condensation. Production batches are therefore conducted with a safety margin that limits the reagent addition rate to maintain internal temperature below 3 °C. The purified secondary amine product isolates as a stable free base, whereas the corresponding product from unsubstituted 2‑aminomethylpyrrole frequently requires immediate salt formation to prevent darkening.
Exposure of the neat compound to temperatures above 80 °C in polar aprotic solvents such as dimethylformamide or N‑methyl‑2‑pyrrolidone triggers slow exothermic polycondensation via amine‑catalysed electrophilic substitution at the free C‑3 and C‑4 positions. Differential scanning calorimetry measurements (sealed crucible, 5 K·min⁻¹ ramp) reveal an onset of thermal activity at 93 ± 2 °C with a total enthalpy release of 280 ± 35 J·g⁻¹. Accelerating rate calorimetry (ARC) data at φ = 1.2 indicate a self‑heating rate of 0.02 K·min⁻¹ at 80 °C, rising to 0.5 K·min⁻¹ at 100 °C. These values place the material in a thermally sensitive category that requires precautions during rotary evaporation of high‑boiling solvents: the bath temperature should not exceed 50 °C, and the vacuum should be broken with nitrogen, not air, to suppress oxidative coupling. When pilot‑plant isolation employs thin‑film evaporation, scraped‑surface units with residence times below 30 s at 60 °C are recommended to keep thermal degradation below 0.5 %.
In formulations intended for electrochemical polymerisation, the 1,5‑dimethyl‑2‑(aminomethyl)pyrrole monomer produces films with markedly higher redox stability than those obtained from 2‑aminomethylpyrrole. Cyclic voltammetry in acetonitrile/0.1 M TBAPF₆ on glassy carbon (100 mV·s⁻¹) shows a single, quasi‑reversible oxidation wave with an anodic peak potential (Eₚ,ₐ) of +0.78 V vs. Ag/Ag⁺, compared with +0.52 V for the unsubstituted monomer and +0.64 V for the 1‑methyl homologue. The elevated oxidation potential correlates with improved environmental stability of the doped conductive state; films retained 80 % of their initial conductivity after 1000 h at 60 °C and 85 % RH, versus 35 % retention for polymer derived from 2‑aminomethylpyrrole under the same conditions. Although published data for large‑area electropolymerisation under industrial conditions remain limited, the observed stability window permits the monomer to be processed in standard electrocoating baths with only a slight nitrogen blanket to maintain bath life.
When employed as a reactive building block in polyamide or polyurea formulations, the low‑melting amine is liquid‑fed into twin‑screw extruders (L/D 40:1, 25 mm co‑rotating) via a heated injection port set to 55 °C. Processing at screw speeds above 300 rpm raises the local material temperature above the thermal onset limit unless barrel zone temperatures downstream are cooled to 40 °C. Trials on a Leistritz ZSE 27 MAXX with gravimetric liquid feeding at 1.5 kg·h⁻¹ into a polyether‑based prepolymer showed that residence‑time‑distribution broadening occurs when the amine feed temperature drops by ≥ 10 °C, leading to blockages at the injection nozzle. A jacketed nozzle assembly with independent temperature control and a 100 µm sintered‑metal filter has proven effective in maintaining steady‑state dispersion.
During these compounding runs, the amine reacts rapidly with isocyanate‑terminated intermediates; the gel time at 80 °C with an NCO‑index of 1.02 is 18 ± 3 s (measured on a Gelnorm gel‑timer), which is 5–7 s longer than the gel time observed with 2‑aminomethylpyrrole under identical stoichiometry. The delayed crosslinking allows better melt‑flow into thin‑wall injection‑moulded cavities with wall thicknesses down to 0.8 mm, thereby reducing short‑shot defects. The final parts exhibit a glass‑transition temperature (Tg, by DSC according to ASTM E1356‑08) of 118 °C, compared with 104 °C for the unsubstituted pyrrole analogue, a difference attributed to the stiffening effect of the 1,5‑dimethyl substitution on chain packing.
A comparative summary of key performance differences relative to structurally related aminomethylpyrroles is given in Table 2.
| Property | 2‑(Aminomethyl)pyrrole | 1‑Methyl‑2‑(aminomethyl)pyrrole | 2‑(Aminomethyl)‑1,5‑dimethylpyrrole |
|---|---|---|---|
| Free N–H | Yes | No | No |
| C‑5 unsubstituted | Yes | Yes | No |
| Oxidative darkening time (acetonitrile, aerated) | 4–6 h | 12–14 h | >48 h |
| Ring‑opening observed during imine formation | 12 % (toluene reflux) | 5 % | < 1 % |
| N‑nitrosation potential | High (secondary alkyl‑N‑nitroso) | Negligible | Negligible |
| Eₚ,ₐ (V vs. Ag/Ag⁺) | +0.52 | +0.64 | +0.78 |
| Gel time (s) with NCO‑index 1.02 at 80 °C | 11 ± 2 | 14 ± 2 | 18 ± 3 |
Storage recommendations derive from the thermal and oxidative stability data. The product is packaged under argon in sealed, amber‑glass bottles or foil‑lined drums. Long‑term storage at 2–8 °C is advised for retention samples; bulk inventory held at 15–25 °C should be consumed within 12 months from the CoA date. Containers must be resealed immediately after use with an inert‑gas purge. The material is incompatible with strong oxidising agents, acid chlorides, and concentrated nitric acid. Spillages are absorbed on vermiculite and neutralised with dilute acetic acid (5 % v/v) prior to disposal following local regulations. REACH registration data for the substance are maintained by the manufacturer; the product does not contain substances of very high concern (SVHC) above 0.1 % w/w.
