Synthesis Route for 1,3-Difluoro-2-Nitrobenzene (2,6-Difluoronitrobenzene)

• Direct nitration of 1,3-difluorobenzene yields 2,6-difluoronitrobenzene as the major isomer under controlled conditions.
• Industrial purity ≥98% is achievable via optimized reaction parameters and fractional distillation.
• NINGBO INNO PHARMCHEM CO.,LTD. offers bulk supply with full COA documentation and competitive bulk price for global B2B clients.

The compound commonly referred to as 1,3-difluoro-2-nitrobenzene (CAS 19064-24-5) is systematically named 2,6-difluoronitrobenzene or 2,6-difluoro-1-nitrobenzene in IUPAC nomenclature. This aromatic building block is a critical intermediate in pharmaceutical, agrochemical, and advanced materials synthesis due to its electron-deficient ring and orthogonal fluorine substitution pattern. As a global manufacturer specializing in high-purity fluoroaromatics, NINGBO INNO PHARMCHEM CO.,LTD. has refined the synthesis route for this molecule to ensure consistent industrial purity, scalability, and cost efficiency for bulk procurement.

Nitration of 1,3-Difluorobenzene: Optimized Reaction Conditions

The most industrially viable manufacturing process for 2,6-difluoronitrobenzene begins with direct electrophilic nitration of 1,3-difluorobenzene. Due to the strong ortho/para-directing nature of fluorine and the meta relationship between the two fluorine atoms, nitration occurs preferentially at the C-2 position (equivalent to C-6 by symmetry), yielding 2,6-difluoronitrobenzene as the dominant product.

Key reaction parameters for maximizing regioselectivity and yield include:

• Nitrating agent: A mixed acid system (HNO₃/H₂SO₄) with controlled molar ratios (typically 1:2 to 1:3 HNO₃:H₂SO₄).
• Temperature: Maintained between 0°C and 10°C to suppress dinitration and side reactions.
• Reaction time: 2–4 hours under vigorous stirring to ensure homogeneity.
• Workup: Quenching into ice water, followed by extraction with dichloromethane or toluene, washing with aqueous NaHCO₃, and drying over anhydrous MgSO₄.

Under these conditions, isolated yields of 85–92% are routinely achieved, with crude purity >95% by GC. Final purification via fractional distillation under reduced pressure (bp ~110–115°C at 10 mmHg) delivers material with ≥98% industrial purity, suitable for downstream Suzuki couplings, nucleophilic aromatic substitutions, or reductive amination sequences.

Alternative Synthetic Pathways to 2,6-Difluoronitrobenzene

While direct nitration remains the most economical route, literature reports alternative approaches that may be relevant for niche applications:

• From 2,6-difluoroaniline: Diazotization followed by treatment with Cu(NO₂)₂ or NaNO₂/Cu (Sandmeyer-type nitration). However, this route suffers from lower overall yield (<70%) and higher cost due to the expensive aniline precursor.
• Halogen exchange/nitration sequences: Starting from chloro- or bromo-nitrobenzenes, but these require harsh fluorination conditions (e.g., KF/crown ether at >200°C), leading to decomposition and poor selectivity.

Notably, the Murray et al. (1989) study in the Journal of Organic Chemistry demonstrated high-yield (>98%) preparation via controlled mononitration, reinforcing the robustness of the direct method. When sourcing high-purity 2,6-Difluoronitrobenzene, buyers should prioritize suppliers with validated analytical data (HPLC, NMR, GC-MS) and batch-specific Certificates of Analysis (COA).

Scalability and Yield Considerations for Industrial Production

At pilot and commercial scale, the nitration process must address heat management, corrosion control, and waste minimization. NINGBO INNO PHARMCHEM CO.,LTD. employs glass-lined or Hastelloy reactors to withstand mixed acid conditions and implements real-time temperature monitoring to prevent exothermic runaway. The mother liquor and wash streams are treated on-site to recover residual organics and neutralize acidity before discharge.

The table below summarizes key technical and commercial specifications for bulk-grade 2,6-difluoronitrobenzene:

Parameter	Specification
CAS Number	19064-24-5
Molecular Formula	C₆H₃F₂NO₂
Molecular Weight	159.09 g/mol
Appearance	Colorless to pale yellow liquid
Purity (GC/HPLC)	≥98.0%
Boiling Point	220.1 ± 20.0 °C at 760 mmHg
Density	1.5 ± 0.1 g/cm³
Flash Point	94.1 ± 10.1 °C
HS Code	2904909090
Bulk Packaging	25 kg HDPE drums or 200 kg steel drums
COA Available	Yes (includes NMR, HPLC, MS, elemental analysis)

For B2B clients requiring multi-kilogram to metric-ton quantities, NINGBO INNO PHARMCHEM CO.,LTD. provides competitive bulk price structures based on annual volume commitments, with lead times as short as 2–3 weeks for standard batches. All shipments include GHS-compliant labeling and SDS documentation aligned with EU REACH and OSHA standards.

In summary, the direct nitration of 1,3-difluorobenzene remains the optimal synthesis route for producing high-purity 2,6-difluoronitrobenzene. With decades of experience in fluoroaromatic chemistry, NINGBO INNO PHARMCHEM CO.,LTD. stands as a trusted global manufacturer delivering consistent quality, regulatory compliance, and scalable supply for demanding industrial applications.