2,3-Difluoro-6-Nitroaniline Grades: Color & Impurity Limits
2,3-Difluoro-6-nitroaniline Purity Grades: COA Parameters and Isomeric Impurity Limits for Agrochemical Coupling
When sourcing 2,3-difluoro-6-nitroaniline (CAS 211693-73-1) for agrochemical synthesis, procurement managers must scrutinize the Certificate of Analysis (COA) beyond a simple HPLC purity percentage. This fluorinated building block, also referred to as 2,3-difluoro-6-nitrophenylamine or 5,6-difluoro-2-nitroaniline, is a critical intermediate in the production of herbicides and fungicides. The presence of regioisomeric impurities, such as the 2,4-difluoro isomer, can significantly impact coupling efficiency in downstream reactions like Suzuki-Miyaura or Buchwald-Hartwig aminations. Our industrial-grade material typically targets a purity of ≥98.0% (HPLC), but the real differentiator lies in the control of specific impurities. For instance, the 2,4-difluoro-6-nitroaniline isomer is a common byproduct from nitration of 2,3-difluoroaniline; we maintain this below 0.5% to ensure consistent reactivity. A typical COA will also report residual solvents (e.g., toluene, DMF) and water content (Karl Fischer). For agrochemical formulators, the absence of heavy metals like palladium or copper (from coupling steps) is crucial to avoid phytotoxicity. Please refer to the batch-specific COA for exact numerical limits, as these are tailored to the synthetic route.
In the context of organic synthesis, this chemical intermediate serves as a versatile scaffold. Its electron-deficient aromatic ring, activated by the nitro group, facilitates nucleophilic aromatic substitution (SNAr) with amines or alkoxides. However, the fluorine atoms at the 2- and 3-positions can undergo unwanted displacement under harsh conditions, leading to defluorinated impurities. Our manufacturing process employs controlled amination to minimize such byproducts. For buyers comparing bulk price quotes, it's essential to align the purity grade with the intended application: a technical grade (≥95%) may suffice for early-stage research, while a custom-synthesized high-purity grade (≥99%) is recommended for late-stage pharmaceutical intermediates. As a global manufacturer, NINGBO INNO PHARMCHEM offers consistent quality across batches, making our product a seamless drop-in replacement for existing supply chains. For a deeper dive into synthesis challenges, see our article on 2,3-Difluoro-6-Nitroaniline In Snar Synthesis: Solvent Incompatibility & Tar Formation Control.
| Parameter | Industrial Grade | High-Purity Grade |
|---|---|---|
| Assay (HPLC, area%) | ≥98.0% | ≥99.0% |
| 2,4-Difluoro-6-nitroaniline Isomer | ≤0.5% | ≤0.2% |
| Other Individual Impurities | ≤0.5% | ≤0.2% |
| Water (KF) | ≤0.5% | ≤0.3% |
| Appearance | Yellow to brown crystalline powder | Light yellow crystalline powder |
Color Stability Under Ambient Storage: Gardner Index Shifts and Impact on Downstream Product Hue
Color is a non-trivial quality indicator for 2,3-difluoro-6-nitroaniline, as it often reflects the presence of oxidative degradation products or trace impurities. Freshly synthesized material typically appears as a pale yellow to light brown crystalline powder. However, upon prolonged storage under ambient conditions, a gradual darkening can occur, shifting the Gardner color index from 2-3 to 6-8. This yellowing is primarily due to the formation of nitroso or azo dimers via photochemical or thermal pathways. For agrochemical formulators, a dark-colored intermediate can impart an undesirable hue to the final product, such as a liquid herbicide concentrate, potentially affecting market acceptance. Our field experience shows that storing the product in sealed, light-resistant containers at temperatures below 25°C effectively retards this discoloration. We have also observed that batches with higher residual acidity (from nitration) tend to darken faster; thus, our washing protocol includes a neutralization step to pH 6-7. While the Gardner index is not a standard specification on most COAs, we can provide this data upon request for sensitive applications. It's worth noting that the color shift does not necessarily correlate with a drop in chemical purity, but it can indicate the onset of degradation that might affect reactivity in subsequent steps.
Non-Standard Metrics for Batch Consistency: Viscosity, Crystallization Behavior, and Filtration Yield
Beyond the typical COA parameters, experienced process chemists monitor several non-standard metrics to ensure batch-to-batch consistency in large-scale syntheses. One such metric is the crystallization behavior of 2,3-difluoro-6-nitroaniline from common solvents like toluene or ethanol/water mixtures. The crystal habit (needles vs. plates) can influence filtration speed and drying efficiency. We have found that a controlled cooling rate (0.5°C/min) from 60°C to 5°C yields a uniform, easily filterable crystalline solid with a typical filtration yield of >90% on a Büchner funnel. Another field-observed parameter is the melt viscosity of the crude product, which can vary depending on the level of oligomeric impurities. A higher viscosity can complicate transfer operations in a plant setting. While we do not publish standard viscosity values, our production team uses a qualitative “flow test” at 80°C to ensure pumpability. For buyers handling the material in cold climates, the crystallization point is critical; the pure compound melts at around 75-78°C, but the presence of impurities can depress this, leading to solidification in IBCs during winter. For detailed guidance on winter handling, refer to our dedicated article: Bulk 2,3-Difluoro-6-Nitroaniline: Winter Crystallization & Ibc Handling For Agrochemicals.
Bulk Packaging and Supply Chain Reliability: IBC and 210L Drum Options for Industrial Procurement
NINGBO INNO PHARMCHEM supplies 2,3-difluoro-6-nitroaniline in standard industrial packaging tailored for safe and efficient handling. For bulk orders, we offer 210L steel drums with polyethylene liners, net weight 25-50 kg depending on density, and 1000L Intermediate Bulk Containers (IBCs) for larger volumes. All packaging complies with UN regulations for solid hazardous materials. The product is classified as a non-flammable solid, but it should be kept away from strong reducing agents due to the nitro group. Our logistics team ensures secure palletization and provides all necessary documentation, including SDS and COA, prior to shipment. As a drop-in replacement for other suppliers, our material matches the physical form (crystalline powder) and packaging configurations, minimizing the need for process adjustments at your facility. We maintain safety stock in our warehouse to support just-in-time deliveries, reducing your inventory carrying costs. For procurement managers, the key advantage is our integrated supply chain: from in-house synthesis of the difluoronitroaniline core to final purification, we control every step, ensuring traceability and consistent quality.
Frequently Asked Questions
What impurity reporting format does your COA follow for 2,3-difluoro-6-nitroaniline?
Our COA reports impurities by HPLC area% with a detection limit of 0.05%. We list individual specified impurities (e.g., 2,4-difluoro isomer, defluorinated analogs) and total unspecified impurities. The format is compliant with ICH Q3A guidelines for new drug substances, adapted for industrial intermediates.
What is the acceptable Gardner color range for your product, and how is it measured?
For our industrial grade, the typical Gardner color is 2-4 when measured as a 10% solution in acetone. For high-purity grade, it is 1-2. We use a Lovibond comparator according to ASTM D1544. Batches exceeding Gardner 6 are rejected for discoloration, even if chemical purity is within spec.
How should I store 2,3-difluoro-6-nitroaniline to prevent yellowing?
Store in a cool (<25°C), dry, well-ventilated area away from direct sunlight. Keep containers tightly closed and protected from light. Under these conditions, the product remains stable for at least 12 months. Avoid exposure to moisture and incompatible materials like strong bases or reducing agents.
Can you provide a sample for compatibility testing with our formulation?
Yes, we offer free samples (10-50 g) for evaluation. Contact our sales team with your application details, and we will ship a representative batch with a provisional COA.
Do you offer custom synthesis or toll manufacturing for derivatives of 2,3-difluoro-6-nitroaniline?
Absolutely. Our R&D team can develop and scale up processes for downstream intermediates, such as 2,3-difluoro-6-nitroaniline derivatives via SNAr or reduction. We operate under strict confidentiality agreements.
Sourcing and Technical Support
As a dedicated manufacturer of fluorinated aromatic intermediates, NINGBO INNO PHARMCHEM provides reliable access to high-quality 2,3-difluoro-6-nitroaniline for agrochemical and pharmaceutical applications. Our product serves as a cost-effective, drop-in replacement for existing supply chains, with identical technical parameters and enhanced supply security. We invite you to review our comprehensive product specifications and discuss your specific impurity limits or packaging needs. To request a batch-specific COA, SDS, or secure a bulk pricing quote, please contact our technical sales team.