2-Bromo-1,3-difluoro-4-nitrobenzene: Handling & Use Protocol

2-Bromo-1,3-difluoro-4-nitrobenzene is a versatile halogenated aromatic building block widely employed in nucleophilic aromatic substitution (SNAr) reactions and cross-coupling chemistry for the synthesis of pharmaceuticals, agrochemicals, and advanced functional materials.

CAS Number

To be confirmed — see current CoA

Molecular Formula

C₆H₂BrF₂NO₂

Molecular Weight

238.99 g/mol

Recommended Storage

Cool, dry, well-ventilated area; away from heat sources and incompatible oxidizers

Key Functional Groups

Aryl bromide, two aryl fluorides, nitro group

Primary Synthetic Applications

SNAr substitution, Suzuki-Miyaura coupling, Buchwald-Hartwig amination

Safety Precautions and Personal Protective Equipment

Before handling 2-Bromo-1,3-difluoro-4-nitrobenzene, consult the current Safety Data Sheet (SDS) provided by Aladdin Scientific. The compound contains a nitro group and halogen substituents that confer both chemical reactivity and potential health hazards.

• PPE required: Chemical-resistant gloves (nitrile or neoprene), laboratory coat, safety goggles, and a face shield when working with larger quantities.
• Ventilation: All weighing, dissolution, and reaction steps must be performed inside a well-functioning chemical fume hood to prevent inhalation of vapors or dust.
• Skin and eye contact: In the event of skin contact, wash immediately with soap and copious water for at least 15 minutes. For eye contact, flush with water and seek immediate medical attention.
• Incompatibilities: Keep away from strong reducing agents, strong bases, and oxidizing agents. Avoid exposure to open flames or high temperatures, as nitroaromatic compounds can be sensitive to shock or heat.
• Waste disposal: Dispose of all waste in accordance with local regulations for halogenated organic solvents and nitroaromatic compounds.

Review flag: Specific GHS hazard classifications and exact LD₅₀ values for this compound should be verified against the Aladdin Scientific SDS prior to use.

Storage and Stability Guidelines

Proper storage of 2-Bromo-1,3-difluoro-4-nitrobenzene is essential to maintain reagent integrity and ensure reproducible results.

• Temperature: Store at room temperature (15–25 °C) in a cool, dry location, unless the current product label specifies otherwise. Refrigerated storage may extend shelf life; confirm with the current CoA.
• Container: Keep tightly sealed in the original amber glass or well-closed plastic container to protect from moisture and light.
• Atmosphere: If the compound is moisture-sensitive, consider storage under inert gas (nitrogen or argon) after first opening.
• Shelf life: Check the expiry date on the product label. Visual inspection for discoloration or unusual odor should be performed before each use; if in doubt, verify purity by TLC, GC, or NMR before critical synthetic steps.

Review flag: Exact recommended storage temperature and confirmed shelf-life data should be taken from the Aladdin Scientific product label and CoA, as these are not specified in the source material.

Representative Protocol: Nucleophilic Aromatic Substitution (SNAr)

The electron-withdrawing nitro group and the two flanking fluorine atoms in 2-Bromo-1,3-difluoro-4-nitrobenzene activate the ring toward nucleophilic aromatic substitution (SNAr), making fluorine atoms excellent leaving groups under mild conditions. The following is a general procedure; optimization for specific nucleophiles and scales is required.

Materials

• 2-Bromo-1,3-difluoro-4-nitrobenzene (Aladdin Scientific, SKU B178976)
• Nucleophile of choice (e.g., primary or secondary amine, thiol, alkoxide)
• Base (e.g., K₂CO₃, Cs₂CO₃, or Et₃N — choice depends on nucleophile pKa)
• Anhydrous polar aprotic solvent (e.g., DMSO, DMF, or MeCN)
• Inert atmosphere (N₂ or Ar) if air-sensitive reagents are used

General Procedure

1. Charge a dry round-bottom flask with a magnetic stir bar. If using air-sensitive nucleophiles, purge the flask with inert gas.
2. Dissolve 2-Bromo-1,3-difluoro-4-nitrobenzene (1.0 equiv) in the chosen anhydrous solvent (concentration: typically 0.1–0.5 M).
3. Add the nucleophile (1.0–1.2 equiv) and base (1.5–2.0 equiv) sequentially.
4. Stir the reaction mixture at the appropriate temperature (room temperature to 80 °C, depending on nucleophile reactivity) and monitor by TLC or LC-MS until starting material is consumed.
5. Upon completion, quench the reaction with water and extract with an organic solvent (e.g., EtOAc or DCM). Wash the organic layer with brine, dry over anhydrous Na₂SO₄ or MgSO₄, filter, and concentrate under reduced pressure.
6. Purify the crude product by column chromatography (silica gel, appropriate eluent) or recrystallization.
7. Confirm product identity and purity by ¹H NMR, ¹⁹F NMR, and HRMS.

Review flag: Specific reaction conditions (temperature, solvent, base, equivalents, and yield) are generalized from textbook-level SNAr principles and have not been taken from a specific literature source. Researchers should optimize conditions for their specific substrate and nucleophile.

Representative Protocol: Suzuki-Miyaura Cross-Coupling via the Aryl Bromide

The aryl bromide functionality in 2-Bromo-1,3-difluoro-4-nitrobenzene can be selectively engaged in palladium-catalyzed Suzuki-Miyaura cross-coupling reactions with arylboronic acids or boronic esters, enabling the construction of biaryl scaffolds relevant to drug discovery and materials science.

General Procedure

1. In a dry Schlenk flask or sealed tube, combine 2-Bromo-1,3-difluoro-4-nitrobenzene (1.0 equiv) and the arylboronic acid or pinacol ester (1.1–1.5 equiv).
2. Add a palladium catalyst (e.g., Pd(PPh₃)₄ or Pd(dppf)Cl₂, 1–5 mol%) and an inorganic base (e.g., K₂CO₃ or Na₂CO₃, 2.0–3.0 equiv).
3. Add a mixed aqueous/organic solvent (e.g., toluene/water, DMF/water, or dioxane/water, typically 4:1 v/v).
4. Purge the reaction mixture with nitrogen or argon for at least 10 minutes.
5. Heat the reaction to 80–100 °C and stir for 4–16 hours, monitoring by TLC or LC-MS.
6. Cool to room temperature, dilute with EtOAc, and wash sequentially with water and brine. Dry the organic layer, filter, and concentrate.
7. Purify by column chromatography on silica gel. Confirm product identity by ¹H NMR, ¹⁹F NMR, and HRMS.

Note: Selectivity between the C–Br and C–F bonds is generally achievable under standard Pd-catalyzed conditions because C–Br bonds are considerably more reactive than C–F bonds toward oxidative addition. Verify chemoselectivity for your specific substrate by analytical methods.

Review flag: Catalyst loading, temperature, and solvent ratios are generalized from textbook-level Suzuki coupling principles. Specific literature citations for this exact substrate are not available in the source material and should be sought from primary literature before use in publication.

Analytical Characterization and Quality Verification

Before use in critical synthetic steps, researchers are advised to verify the purity and identity of 2-Bromo-1,3-difluoro-4-nitrobenzene using the following analytical approaches:

• ¹H NMR: Expect signals consistent with the aromatic proton environment of a 1,2,3,4-tetrasubstituted benzene ring. The two aromatic protons flanking the nitro group and between the substituents should appear in the δ 7.5–8.5 ppm region.
• ¹⁹F NMR: Two distinct fluorine signals are expected, reflecting the non-equivalent 1- and 3-positions of the fluorine atoms on the aromatic ring.
• GC or HPLC purity: Purity ≥95% is typically acceptable for synthetic use; confirm against the Aladdin Scientific CoA specification.
• Melting point: If the compound is a solid, compare the observed melting point with the value stated on the CoA.
• Mass spectrometry: Confirm the molecular ion cluster consistent with the isotope pattern of one bromine and two fluorine atoms (M⁺ at m/z ≈ 239/241 in a ~1:1 ratio for ⁷⁹Br/⁸¹Br).

Review flag: Specific NMR chemical shift values and melting point data for this compound are not provided in the source material. Researchers should consult the product CoA or primary literature for reference values.

Frequently asked questions

What are the recommended solvents for dissolving 2-Bromo-1,3-difluoro-4-nitrobenzene?

2-Bromo-1,3-difluoro-4-nitrobenzene is a halogenated aromatic compound expected to be soluble in common organic solvents such as dichloromethane (DCM), chloroform, ethyl acetate, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), and acetonitrile. It is generally insoluble in water. Solvent selection should be guided by downstream reaction requirements and compatibility with reagents used.

How should I dispose of waste containing 2-Bromo-1,3-difluoro-4-nitrobenzene?

Waste containing 2-Bromo-1,3-difluoro-4-nitrobenzene should be collected in appropriately labeled halogenated organic waste containers and disposed of in accordance with your institution's chemical waste management procedures and applicable local, national, and international regulations. Do not pour down the drain or dispose of in general trash. Consult the SDS for specific disposal guidance.

References

1. March, J.; Smith, M. B. March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 7th ed.; Wiley: Hoboken, NJ, 2013. (General SNAr and cross-coupling principles)
2. Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chem. Rev. 1995, 95, 2457–2483. doi:10.1021/cr00039a007
3. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (Nucleophilic aromatic substitution chapter)

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