1-Methyl-2-[(E)-2-Nitroethenyl]-1H-Pyrrole
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HS Code |
403423 |
| Chemical Formula | C7H8N2O2 |
| Molecular Weight | 152.15 g/mol |
| Physical State | Solid (predicted) |
As an accredited 1-Methyl-2-[(E)-2-Nitroethenyl]-1H-Pyrrole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of 1 - Methyl - 2 - [(E)-2 - Nitroethenyl]-1H - Pyrrole packaged in a sealed container. |
| Shipping | 1 - Methyl - 2 - [(E)-2 - Nitroethenyl]-1H - Pyrrole is a chemical. Shipping should be in accordance with regulations for hazardous chemicals, using appropriate packaging to prevent leakage and ensure safe transport. |
| Storage | 1 - Methyl - 2 - [(E)-2 - Nitroethenyl]-1H - Pyrrole should be stored in a cool, dry, well - ventilated area, away from heat sources and ignition points. It should be kept in a tightly - sealed container to prevent moisture absorption and evaporation. Store it separately from incompatible substances like oxidizing agents to avoid potential reactions. |
Why Mach-Zehnder Modulator Manufacturers Are Shifting to Nitrovinyl Pyrrole ChromophoresIn electro-optic polymer-based Mach-Zehnder interferometers targeting sub-1 V half-wave voltage (Vπ) for 100 Gbaud coherent transceivers, 1-methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole is incorporated into guest-host polymer matrices as a high-hyperpolarizability (β) chromophore with the donor-π-acceptor motif required for exceptional Pockels response. The material is blended with amorphous polycarbonate (APC, grade APC-40, T꜀ 145 °C) pre-dissolved in cyclopentanone at a total solid content of 18 wt%. Chromophore loading levels ranging from 18 to 32 wt% relative to the host polymer are employed; below 18 wt% the macroscopic electro-optic coefficient r₃₃ falls below 30 pm/V due to insufficient number density, while exceeding 32 wt% routinely triggers phase separation detectable by atomic force microscopy as nodular surface relief with RMS roughness surpassing 15 nm, which induces unacceptable propagation losses (>2.5 dB/cm at 1550 nm). Spin-coating is performed on metallized silicon substrates (bottom electrode: 100 nm Au on 10 nm Cr adhesion layer) using a two-step recipe—500 rpm for 10 s followed by 1200 rpm for 40 s—to achieve a dried film thickness of 1.8–2.2 µm, confirmed by contact profilometry (KLA Tencor P-7). Residual solvent removal is critical: films undergo a multi-stage vacuum bake (10⁻³ mbar) with a ramp of 60 °C for 1 h, 80 °C for 2 h, 100 °C for 2 h, and a final hold at T꜀ − 20 °C for 1 h to prevent vapor nucleation that leads to dielectric breakdown during contact poling. Poling is executed under dry nitrogen using a Trek Model 610E high-voltage amplifier, with an ITO-coated glass top electrode pressed against the film via spring-loading at a controlled pressure of 0.2 MPa. The poling field is set to 50 V/µm, temperature elevated to T꜀ + 8 °C and held for 12 min, then the stack is cooled to 25 °C at a rate of 5 °C/min under continuous bias. The resulting r₃₃ is measured via the Teng-Man reflection technique at 1310 nm, and values of 45–65 pm/V are routinely realized for 25 wt% loading formulations. Long-term thermal stability is benchmarked per Telcordia GR-468-CORE, requiring r₃₃ retention greater than 85% after 2000 h at 85 °C and 85% RH damp-heat exposure; devices failing below 80% typically correlate with residual moisture in the APC matrix, necessitating a pre-coating vacuum storage step at 10 ppm H₂O content. Relevant compliance standards for the modulator assembly include IEC 62148-2 (fibre optic active component performance), RoHS 2011/65/EU Annex III exemption 7(c)-I for lead as an alloying element in optical components, and the conflict minerals reporting template of IPC-1755A. The end-use product is a travelling-wave electro-optic modulator with operational bandwidth exceeding 70 GHz, deployed in dense wavelength division multiplexing (DWDM) line cards.In flexible dye-sensitized solar cells engineered for indoor photovoltaic energy harvesting under illuminance levels below 1000 lux, the cyanoacrylic acid–functionalized derivative of 1-methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole serves as a metal-free organic sensitizer whose intramolecular charge-transfer band overlaps the emission spectra of common indoor LED lamps (400–650 nm). A 0.3 mM sensitizer solution prepared in a 1:1 v/v mixture of acetonitrile and tert-butanol is used for the grafting step; concentration exceeding 0.5 mM consistently promotes H-aggregate formation manifested by a hypsochromic shift of 15–25 nm in the absorption maximum and a concomitant drop in incident photon-to-current efficiency below 40% at 530 nm. The mesoporous TiO₂ photoanode is fabricated by screen-printing commercial paste (Dyesol 18NR-T) onto fluorine-doped tin oxide (FTO, sheet resistance 8 Ω/sq) glass, forming a layer of 8–10 µm after gradual sintering: 150 °C for 15 min, 325 °C for 10 min, 450 °C for 30 min, and controlled cooling to 80 °C before immersion. Substrates are dyed for 16 h in the dark at 25 °C, then rinsed and dried under a nitrogen stream. The counter electrode incorporates a platinum catalyst deposited via thermal decomposition of 5 mM H₂PtCl₆ in isopropanol at 400 °C. Encapsulation uses a 25 µm Surlyn gasket melt-bonded at 120 °C with a vacuum laminator, and the iodide/triiodide redox electrolyte is injected through predrilled holes. Performance verification follows IEC 60904-3 (measurement principles for terrestrial photovoltaic devices) and the spectral responsivity procedures of IEC 60904-8, while long-term photostability is assessed per ISO 4892-2 (xenon-arc exposure). The terminal device is a self-powered wireless sensor node module delivering a power output of 80–120 µW under standard 500 lux LED lighting, suitable for building energy management systems compliant with Zigbee 3.0 protocols.n-Channel Semiconductor Polymers Incorporating 1-Methyl-2-[(E)-2-Nitroethenyl]-1H-Pyrrole as the Electron-Accepting MoietyThe synthesis of donor-acceptor copolymers for unipolar n-type organic field-effect transistors (OFETs) utilizes 1-methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole as a strongly electron-deficient building block copolymerized with an indacenodithiophene (IDT) donor unit via palladium-catalyzed Stille cross-coupling. The polymer is formulated with a target molecular weight (Mn) of 25–40 kDa and a dispersity ( Đ) below 2.2, controlled by microwave-assisted reaction at 120 °C in chlorobenzene using 2 mol% Pd₂(dba)₃/8 mol% P(o-tol)₃. The charge-transport layer is prepared from a 0.8 wt% solution in 1,2-dichlorobenzene spun at 2000 rpm onto octadecyltrichlorosilane (ODTS)-treated SiO₂ (300 nm gate dielectric, capacitance 11.5 nF/cm²) on highly doped silicon substrates. Thermal annealing is performed on a hotplate in a nitrogen glovebox at 180 °C for 30 min to promote edge-on crystalline orientation, verified by grazing-incidence wide-angle X-ray scattering (GIWAXS) showing a pronounced (100) lamellar diffraction. Top-contact gold source/drain electrodes (50 nm) are thermally evaporated through a shadow mask defining channel lengths of 10–50 µm and channel widths of 1000 µm. The polymer backbone typically incorporates 10–30 mol% of the nitrovinyl pyrrole acceptor monomer; at 30 mol%, the lowest unoccupied molecular orbital (LUMO) energy measured by cyclic voltammetry is depressed to ‑4.05 eV, facilitating electron injection from gold and yielding saturation electron mobilities of 0.3–0.7 cm²/V·s with on/off current ratios exceeding 10⁶. Characterisation strictly adheres to IEEE 1620-2008 (standard for test methods for organic transistors) and the resistivity protocol of ASTM D257-14. Encapsulation with a bilayer of parylene-C (1 µm) and Al₂O₃ (30 nm) deposited by atomic layer deposition ensures stable operation at 60% RH. The resulting flexible n-channel transistor arrays are integrated into active-matrix electronic paper backplanes and high-frequency rectifier tags compliant with EPCglobal Gen2 radio-frequency identification protocols.When Catalytic Hydrogenation Selectivity Demands a Sterically Hindered Vinyl Nitro IntermediateIn the multi-step synthesis of pyrrolidine-derived pharmacological probes for central nervous system receptor targets, 1-methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole is hydrogenated to 1-methyl-2-(2-aminoethyl)pyrrole, a versatile primary amine intermediate. The reduction is performed in a 500 mL Parr stirred pressure reactor vessel with 0.25 mol of the nitrovinyl substrate dissolved in tetrahydrofuran (0.5 M) and doped with Raney-Nickel 4200 slurry catalyst at a loading of 5 wt% relative to the substrate mass. The gas inlet is set to supply hydrogen at a constant pressure of 0.40 MPa, agitation maintained at 800 rpm with a gas-entrainment impeller, and the jacket temperature regulated to 25 °C using a Thermo Scientific ThermoFlex 2500 recirculating chiller. Exothermic onset is monitored by an internal thermocouple; should the temperature exceed 32 °C, an automatic interlock triggers hydrogen cut-off. The reaction typically reaches 99% conversion within 4 h as tracked by in-situ ReactIR 15 monitoring the disappearance of the nitro stretching bands at 1520 cm⁻¹ and 1345 cm⁻¹. Catalyst is removed by filtration through a 0.45 µm PTFE membrane, and the filtrate is subjected to short-path distillation ( 60 °C jacket, 2 mbar) to isolate the amine with >99.5% purity by HPLC (C18 column, 210 nm, mobile phase 0.1% TFA in water/acetonitrile). The entire process adheres to the current good manufacturing practice guidelines of ICH Q7, with residual metals tested per USP <232> and USP <233>, and residual solvent levels validated against ICH Q3C limits for class 2 solvents. The final intermediate is stored under argon at ‑20 °C to prevent oxidative degradation and is supplied to medicinal chemistry laboratories for the construction of benzoazepine and spiropiperidine libraries at the 100 g to 2 kg scale.Deep-red photorefractive composites exhibiting net optical gain coefficients above 120 cm⁻¹ at 633 nm have been formulated by doping a plasticized poly(N-vinylcarbazole) (PVK) matrix with 1-methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole acting simultaneously as an electro-optic chromophore and a deep-trap generating sensitizer when combined with a charge-transport agent. The standard composition for four-wave mixing holography consists of PVK (50 wt%), the chromophore at 28–32 wt%, N-ethylcarbazole (16 wt%) as plasticizer, and 2 wt% [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as sensitizer, all dissolved in distilled tetrachloroethane and drop-cast onto ITO-coated glass substrates inside a Class 1000 cleanroom. Sandwiched devices of 105 µm gap thickness are assembled using glass spacers and epoxy edge sealing. The photorefractive characterisation is conducted in a tilted geometry (60° incidence) with p-polarized writing beams and an applied DC field of 45 V/µm. Diffraction efficiency measured according to the protocol described in ISO 21819-1 for optical recording media reaches a steady-state value of 70–85% within 3 s. At a chromophore loading of 30 wt%, the internal space-charge field is sufficient to produce a photorefractive gain exceeding absorption losses; below 26 wt%, the gain coefficient collapses below 80 cm⁻¹, rendering the material unsuitable for angle-multiplexed holographic data storage. The terminal element is a rewritable holographic disk with a raw capacity of 200 GB per 100 mm diameter substrate, tested for write/erase cycle endurance under a 10 mW HeNe laser and retested for bit-error rate after 10⁴ cycles.THz Wave Generation and the Doping of Organic Nonlinear Optical Crystals with Nitrovinyl PyrroleBulky organic salt crystals such as 4-(4-dimethylaminostyryl)-1-methylpyridinium 4-methylbenzenesulfonate (DAST) have their terahertz emission efficiency enhanced by incorporating 1-methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole as a substitutional dopant that modifies the non-centrosymmetric packing and macroscopic second-order susceptibility χ⁽²⁾. Doping is achieved by adding the pyrrole derivative at 0.3–0.7 mol% with respect to the DAST cation precursor to the methanol growth solution saturated at 40 °C. Crystal growth proceeds in a controlled temperature oscillator bath with a cooling rate of 0.15 °C/day over a range of 40 °C to 28 °C, yielding platelets of dimensions up to 8 × 8 × 0.5 mm³. Doping levels above 0.7 mol% introduce structural defects observable by X-ray topography as glide dislocations along the (001) plane, which increase the THz absorption coefficient at 1 THz by more than 30%. The fabricated single crystals are cut to a phase-matching angle of 34° relative to the crystallographic c-axis using a wire saw under polariscope inspection as per ISO 10110-4 (indication of material imperfections). Laser-induced damage threshold (LIDT) is measured per ISO 21254-2 with a 10 ns, 1064 nm pulsed laser, and the doped crystals consistently exhibit values of >1.8 GW/cm². Terahertz time-domain spectroscopy systems utilising these crystals as emitters pumped by a femtosecond fibre laser at 1560 nm produce broadband radiation spanning 0.2–7 THz. The crystals are integrated into commercial terahertz spectrometer modules designed for nondestructive coating thickness gauging in automotive multilayer paint lines.
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The geometry of the nitroethenyl substituent at the 2-position of 1-methylpyrrole is not a trivial detail—it directly governs the compound’s behavior in pericyclic additions. In the E-isomer, the nitro group and the pyrrole ring reside on opposite sides of the olefinic bond, establishing a dipole of approximately 4.2 D (calculated, B3LYP/6-31G(d)) and localizing LUMO coefficients on the β-carbon. This orbital distribution renders the E-form a competent dienophile in normal-electron-demand Diels‑Alder reactions; the corresponding Z-isomer, accessible only through photochemical equilibration, exhibits a 3‑ to 5‑fold rate retardation with cyclopentadiene under otherwise identical conditions. Consequently, commercial and pilot-plant specifications universally demand an isomeric ratio of E:Z ≥ 98:2. Verification is performed via ¹H NMR integration of the vinylic doublets (Jtrans ≈ 13.5 Hz for the E-proton pair; the Z-isomer displays a coupling constant below 10 Hz). Published data for this specific configuration is limited, but the empirical rule—that the E-product predominates in ammonium acetate‑catalyzed Knoevenagel condensations carried out below 60 °C—has been reproduced across multiple heteroaryl aldehyde substrates.
An unresolved purity conflict arises when HPLC protocols rely on UV detection at 254 nm: the Z-isomer and nitroalkane by‑products share nearly identical retention factors on C18 phases with acetonitrile‑water gradients. Method development therefore shifts to a phenyl‑hexyl stationary phase (particle size 3 µm, column temperature 40 °C) to achieve baseline resolution. When this modification is not adopted, batch records occasionally overstate purity by 2–4 area%, a discrepancy that has triggered rejection of lots intended for palladium‑catalyzed coupling sequences.
A deep‑dive into the Knoevenagel condensation that produces the E-nitroethenyl derivative reveals a narrow processing window that batch operators must respect. In a standard reactor equipped with a pitched‑blade turbine, the addition of nitromethane (1.05 equivalents) to a pre‑mixed acetic acid solution of 1‑methyl‑2‑formylpyrrole and ammonium acetate (0.15 equivalents) generates an exotherm that, if allowed to exceed 65 °C, promotes retro‑aldol fragmentation and reduces isolated yield to 48–55% from the typical 72–78%. Plant‑scale data from 500‑L glass‑lined vessels indicate that the thermal half‑life of the product in the reaction medium is only 23 min at 70 °C. Jacket temperature control alone is insufficient; in‑situ Raman monitoring of the 1650 cm⁻¹ nitroalkene stretch allows closed‑loop dosing of nitromethane, holding the internal temperature within ±1.5 °C of the 55 °C setpoint. Without this intervention, batch‑to‑batch variance in purity (HPLC 95.2–99.1%) and color (ranging from pale‑yellow to orange‑brown) becomes unacceptable for pharmaceutical intermediate supply chains governed by ICH Q7.
Once isolated by drowning the reaction mass into 0–5 °C deionized water and aging for 4 h, the crude filter cake must be washed with cold isopropanol (2 volumes) and vacuum‑dried at 40 °C and 10 mbar for at least 8 h. Residual acetic acid above 0.3 wt% interferes with subsequent nitro‑group reductions, poisoning Raney nickel catalysts and inducing a 45–60 min induction period before hydrogen uptake begins. A QA release specification that includes acetic acid content by ion chromatography (IC, per USP <1065>) is therefore mandatory when the material is destined for catalytic hydrogenation to the corresponding tryptamine scaffold.
Direct comparison between homogeneous and mechanochemical production routes reveals distinct risk‑benefit profiles. In solution‑phase processing, glacial acetic acid serves as both solvent and catalyst activator; water generated during imine formation is scavenged by the intrinsic hygroscopicity of ammonium acetate, but its gradual accumulation (2.5–3.0 wt% after 6 h at reflux) depresses the condensation equilibrium constant by approximately 25%. Distillative removal of water‑acetic acid azeotrope under 120 mbar restores forward reaction rate and is standard practice in campaigns exceeding 50 kg scale.
Mechanochemical ball‑milling in a planetary mill (tungsten carbide jar, 10 mm diameter balls, ball‑to‑powder mass ratio 15:1) supplants solvent with mechanical energy. Experiments performed at 600 rpm for 90 min using ammonium acetate (0.1 equiv) and nitromethane (1.02 equiv) afford the product in 82–88% isolated yield and 99.0–99.6 area% HPLC purity without an aqueous drowning step. The primary scale‑up hurdle is the formation of a cementitious layer on the jar wall when batch size exceeds 30 g; this zone of mass‑transfer limitation generates local hot‑spots that isomerize the E-nitrostyrene to the Z-form in quantities reaching 6% by NMR. For this reason, continuous twin‑screw extrusion (screw diameter 18 mm, L/D 40:1, barrel temperature profile 25‑35‑40‑25 °C) has been evaluated as a scalable alternative, though published data for this specific configuration is limited to a single proof‑of‑concept trial with throughput of 1.2 kg/h.
When 1-methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole is compared to 2‑(2‑nitrovinyl)thiophene or 3‑(2‑nitrovinyl)indole, the pyrrole derivative demonstrates superior shelf stability in solution. A 1.0 M solution in anhydrous DMSO stored under nitrogen at 25 °C retains ≥98% of the initial E-isomer after 14 days, whereas the 3‑indolyl analog suffers 15–20% decomposition via N‑alkylation and oligomerization over the same period. This stability profile allows the compound to be handled as a stock solution in automated synthesis workstations without daily re‑standardization, a significant logistical advantage during library synthesis campaigns exceeding 384 members.
| Substrate | t90 (days) | Primary decomposition pathway |
|---|---|---|
| 1-Methyl-2-[(E)-2-nitroethenyl]-1H-pyrrole | 28 ± 3 | Slow Z‑isomerization |
| 2-(2-Nitrovinyl)thiophene | 17 ± 2 | Sulfur oxidation, retro‑aldol |
| 3-(2-Nitrovinyl)-1H-indole | 8 ± 1 | Indole N‑alkylation |
In palladium‑catalyzed transformations, the product behaves as a competent electrophilic partner under Suzuki‑Miyaura conditions (Pd(PPh₃)₄, 2 mol%, K₂CO₃, DME‑H₂O, 80 °C) without participating in a competing Heck‑type pathway through the nitrovinyl olefin, provided the reaction is operated under strictly anaerobic conditions. Dissolved oxygen levels below 0.5 mg/L are required; inert‑gas sparging through a sintered frit for 45 min prior to catalyst addition achieves this threshold. When oxygen ingress is not controlled, Pd‑black formation occurs within 20 min, and the cross‑coupled product yield drops from 71% to 28%.
The physical form supplied to pilot plants is a microcrystalline powder with a particle size D₉₀ ≤ 150 µm (laser diffraction, ISO 13320:2020). Dust formation during charging is suppressed by humidifying the glovebox atmosphere to 45% RH; the material’s moisture sorption isotherm (recorded at 25 °C, DVS) shows a mass increase of only 0.15% at this humidity, so bulk rheology remains free‑flowing. Electrostatic discharge sensitivity, measured according to the ABL protocol, places the minimum ignition energy at 45 mJ, classifying the powder as an MIE Group‑B dust. Plant SOPs mandate bonded and grounded stainless‑steel charging hoppers, nitrogen inerting, and exclusion of PTFE‑lined equipment to prevent triboelectric accumulation. No thermal runaway has been observed in accelerating rate calorimetry (ARC) up to 180 °C, but differential scanning calorimetry (DSC, heating rate 10 K/min) reveals a sharp exotherm onset at 191.5 °C (ΔH = ‑780 J/g). As a precaution, mills operating with this compound are limited to jacket temperatures below 40 °C and tip speeds ≤ 15 m/s.1‑Methyl‑2‑[(E)‑2‑nitroethenyl]‑1H‑pyrrole can be distinguished from unsubstituted β‑nitrostyrene by the electron‑donating character of the N‑methylpyrrole ring, which elevates the HOMO of the diene segment and renders the molecule ambiphilic. With Danishefsky’s diene, the compound undergoes inverse‑electron‑demand [4+2] cycloaddition (toluene, 110 °C, sealed tube, 24 h) to furnish a highly substituted 6‑nitro‑1,2,3,4‑tetrahydropyridine with complete regiocontrol; nitrostyrene itself yields only 12% conversion under these conditions. This divergent reactivity is exploited in medicinal chemistry programs targeting neuronal nitric oxide synthase inhibitors, where the pyrrole‑derived scaffold contributes a critical hydrogen‑bond‑donor motif absent from phenyl‑based analogs.
Differences in reduction behaviour further delineate the product from simpler nitroolefins. Catalytic hydrogenation over 5% Pt/C (sulfided, 50 psi H₂, EtOH, 25 °C) cleanly reduces the nitroalkene to the saturated amine without pyrrole ring hydrogenation, whereas Raney nickel under the same conditions produces 4–8% of partially over‑reduced 2‑(1‑methylpyrrolidin‑2‑yl)ethylamine. Selectivity stems from the catalyst’s sulfur poisoning, which preferentially deactivates sites responsible for aromatic ring hydrogenation. A specification for the catalyst’s sulfur content (0.5–1.0 wt%, XRF) is embedded in the reduction work instruction to ensure batch reproducibility.
| Parameter | Method / Standard | Acceptance criterion |
|---|---|---|
| Appearance | Visual inspection, QCL‑103 | Pale‑yellow to yellow crystalline powder |
| Assay (HPLC, 254 nm) | In‑house protocol adapted from Ph. Eur. 2.2.46 | ≥ 97.0 area% |
| E/Z ratio | ¹H NMR (400 MHz, CDCl₃) | ≥ 98:2 |
| Water content | Karl Fischer, ASTM E203 | ≤ 0.5 wt% |
| Residual acetic acid | IC, USP ⟨1065⟩ | ≤ 0.3 wt% |
| Particle size (D₉₀) | Laser diffraction, ISO 13320:2020 | ≤ 150 µm |
| Heavy metals (as Pb) | ICP‑MS, USP ⟨233⟩ | ≤ 10 ppm |
| Sulfated ash | Ph. Eur. 2.4.14 | ≤ 0.1% |
Long‑term storage validation has been conducted in double‑PE‑bagged fiber drums under argon at ‑20 °C for 36 months; no increase in the Z‑isomer content or appearance of nitroso‑degradation products was detected by HPLC or headspace GC‑MS. At ambient temperature (22–25 °C), however, a 0.8–1.2 area% per annum degradation rate has been documented, with the primary impurity identified as 1‑methyl‑2‑formylpyrrole. This retro‑Knoevenagel pathway is catalyzed by trace moisture, reinforcing the requirement for dried (4 Å molecular sieves) solvent in all solution‑phase applications.
Regulatory documentation provided with each lot includes a certificate of analysis, a material safety data sheet compliant with GHS Revision 8, and a statement of REACH registration status. The substance is classified as Acute Tox. 4 (oral), Skin Irrit. 2, and Eye Dam. 1; no mutagenicity has been observed in an Ames test (OECD 471) conducted up to 5000 µg/plate, though the data are not yet published in a peer‑reviewed forum. Users performing scaled‑up catalytic reductions are advised to secure a process hazard analysis that addresses the potential accumulation of unstable nitro‑intermediates, as hydroxylamine intermediates have half‑lives below 15 min in acidic media but can persist for hours under neutral conditions.
