2,4-Difluoro-5-nitrophenol: Handling & Application Protocol

2,4-Difluoro-5-nitrophenol is a halogenated, electron-deficient aromatic building block widely employed in nucleophilic aromatic substitution (SNAr) chemistry and as a key intermediate in the synthesis of pharmaceuticals, agrochemicals, and functional materials.

CAS / SKU

D586424 (Aladdin SKU); refer to CoA for CAS confirmation

Molecular Formula

C₆H₃F₂NO₃

Molecular Weight

175.09 g/mol

Appearance

Pale yellow to yellow crystalline solid (typical); verify with CoA

Key Functional Groups

Phenol –OH, two aryl fluorines (C-2, C-4), nitro group (C-5)

Recommended Storage

Cool, dry place; away from light and moisture; verify exact conditions on CoA

Primary Application

SNAr reactions, pharmaceutical intermediate synthesis, agrochemical research

Chemical Properties and Reactivity Overview

2,4-Difluoro-5-nitrophenol (Aladdin SKU D586424; molecular formula C₆H₃F₂NO₃; MW 175.09 g/mol) is an electron-poor aromatic phenol bearing two fluorine substituents at the 2- and 4-positions and a nitro group at the 5-position. The combined electron-withdrawing effects of the fluorine atoms and the nitro group strongly activate the ring toward nucleophilic aromatic substitution (SNAr), making the C–F bonds at C-2 and C-4 exceptionally reactive toward oxygen-, nitrogen-, and sulfur-centered nucleophiles.

The free phenolic hydroxyl group confers additional versatility: it can be O-alkylated, O-acylated, or used as a directing handle for further functionalization. The nitro group may be selectively reduced to an amine under standard catalytic hydrogenation or iron/acid conditions, enabling access to the corresponding aniline derivative for downstream coupling reactions.

Note: Exact physical constants (melting point, solubility data, purity specification) should be confirmed from the current Aladdin Certificate of Analysis (CoA) supplied with each lot.

Safety and Handling Requirements

General Precautions: 2,4-Difluoro-5-nitrophenol is a nitroaromatic compound and should be treated as a potential irritant and oxidizing hazard. Always consult the current Safety Data Sheet (SDS) provided by Aladdin Scientific before use.

• Personal Protective Equipment (PPE): Wear nitrile gloves, safety glasses or a face shield, and a laboratory coat. Work in a well-ventilated fume hood at all times.
• Inhalation: Avoid breathing dust or vapors. Use respiratory protection if adequate ventilation cannot be ensured.
• Skin/Eye Contact: In the event of contact, flush the affected area immediately with copious amounts of water for at least 15 minutes and seek medical advice.
• Storage: Store in a tightly closed container in a cool, dry, well-ventilated location away from heat sources, strong bases, strong reducing agents, and flammable materials. Specific storage temperature should be confirmed from the product CoA and SDS.
• Disposal: Dispose of waste in accordance with local, regional, and national regulations applicable to halogenated aromatic compounds.

Review flag: Specific GHS hazard classifications and H/P statements must be verified from the current Aladdin SDS for lot D586424.

Stock Solution Preparation Protocol

The following protocol describes preparation of a 100 mM stock solution for use in SNAr reaction scouting or biological assay applications. Adjust scale and concentration as required by your experimental design.

1. Determine required volume: Calculate the mass of 2,4-Difluoro-5-nitrophenol needed. For 10 mL of 100 mM stock: mass = 0.01 L × 0.1 mol/L × 175.09 g/mol = 175.1 mg.
2. Weigh accurately: Tare a clean, dry glass vial or weighing boat. Transfer the compound from its container using a clean spatula and weigh to ±0.1 mg on an analytical balance. Re-seal the original container immediately to prevent moisture uptake.
3. Select solvent: The compound is expected to dissolve readily in polar aprotic solvents such as DMSO, DMF, or acetonitrile. For aqueous applications, prepare a primary stock in DMSO and dilute into aqueous buffer (keep final DMSO ≤1% v/v to avoid assay interference). Verify actual solubility from CoA or by preliminary dissolution test.
4. Dissolve: Add approximately 80% of the target solvent volume to the weighed compound. Vortex or stir gently until fully dissolved, then make up to the final volume with additional solvent. Filter through a 0.22 µm PTFE syringe filter if particulates are observed.
5. Label and store: Label the vial with compound name, SKU (D586424), lot number, concentration, solvent, date prepared, and preparer's initials. Store at −20 °C under inert atmosphere (N₂ or Ar cap) or as directed by the CoA.
6. Quality check: Record the UV-Vis absorption spectrum if a spectrophotometer is available; nitroaromatic phenols typically exhibit absorption in the 300–400 nm region (exact λmax should be confirmed experimentally).

Review flag: Actual solubility values in specific solvents and the UV-Vis absorption maximum have not been sourced from the product datasheet and require experimental verification.

Representative Synthetic Applications

2,4-Difluoro-5-nitrophenol serves as a versatile electrophilic building block in several synthetic strategies:

1. Nucleophilic Aromatic Substitution (SNAr)

The C-4 fluorine is the most electrophilic site due to the combined para-directing influence of the phenol oxygen and the ortho/para-activating nitro group at C-5 (acting as an ortho activator to C-4). Treatment with amines (primary or secondary), thiols, or alkoxides under mild base conditions (e.g., K₂CO₃ in DMF or acetonitrile, 0 °C to room temperature) selectively displaces the C-4 fluorine to give diaryl ethers, diaryl thioethers, or N-aryl products. The remaining C-2 fluorine can be displaced under more forcing conditions or with more reactive nucleophiles, enabling sequential diversification.

2. Phenol O-Functionalization

The phenolic –OH can be protected as a methyl ether (MeI, K₂CO₃), a benzyl ether, or an aryl triflate to modulate reactivity before SNAr. Alternatively, the free phenol can be exploited as a coupling partner in transition-metal-catalyzed C–O bond forming reactions.

3. Nitro Group Reduction

Catalytic hydrogenation (H₂, Pd/C, EtOH, room temperature) or chemical reduction (Fe powder, NH₄Cl, EtOH/H₂O) selectively reduces the nitro group to an amine without affecting the aryl C–F bonds, furnishing 5-amino-2,4-difluorophenol as an aniline intermediate for further elaboration (e.g., diazotization, amide coupling, reductive amination).

Review flag: Specific reaction conditions, yields, and literature precedents for these transformations have not been sourced from peer-reviewed publications. Users should independently validate conditions and consult primary literature.

Quality Control and Troubleshooting

Verifying Compound Identity and Purity: Upon receipt of Aladdin SKU D586424, compare the product with the Certificate of Analysis (CoA) for purity (typically assessed by HPLC or GC), appearance, and physical constants. Retain the CoA for laboratory records.

Issue	Possible Cause	Recommended Action
Poor or incomplete dissolution	Inadequate solvent choice; moisture contamination	Switch to a stronger polar aprotic solvent (DMSO preferred); gently warm to 40–50 °C; ensure compound is anhydrous
Low SNAr yield	Insufficient base; competing O-alkylation of phenol; moisture in reaction	Use anhydrous solvent and base; consider protecting the phenol –OH prior to SNAr; optimize temperature and equivalents
Color change in stock solution	Degradation or oxidation; exposure to light or moisture	Prepare fresh stock; store under inert gas at −20 °C; protect from light using amber vials
Product purity below specification	Lot-to-lot variability; improper storage	Request re-analysis CoA from Aladdin; store unopened vials per label instructions

Review flag: Specific purity thresholds and analytical methods are not stated in the provided source material and must be confirmed from the product CoA.

Frequently asked questions

What solvents are recommended for dissolving 2,4-Difluoro-5-nitrophenol?

2,4-Difluoro-5-nitrophenol is expected to dissolve well in polar aprotic solvents such as DMSO, DMF, and acetonitrile. For aqueous applications, prepare a concentrated stock in DMSO and dilute into the aqueous medium, keeping the final DMSO content at or below 1% v/v. Actual solubility should be confirmed from the product CoA or by a preliminary dissolution test.

Which C–F bond is more reactive toward SNAr, and why?

The C-4 fluorine is generally more reactive toward SNAr because it benefits from the combined electron-withdrawing activation of both the phenol oxygen (para relationship) and the nitro group at C-5 (ortho relationship to C-4). The resulting enhanced electrophilicity at C-4 allows selective displacement under milder conditions compared with the C-2 fluorine, which can be targeted under more forcing conditions for sequential functionalization.

How should 2,4-Difluoro-5-nitrophenol be stored to maintain stability?

Store the compound in a tightly sealed container in a cool, dry, well-ventilated location away from light, moisture, heat, and incompatible materials such as strong bases and reducing agents. Stock solutions should be stored at −20 °C under an inert gas atmosphere (nitrogen or argon) in amber vials. Always consult the specific storage conditions stated on the Aladdin CoA and SDS for lot D586424.

Can the nitro group of 2,4-Difluoro-5-nitrophenol be selectively reduced without affecting the C–F bonds?

Yes. Standard nitro-group reduction conditions such as catalytic hydrogenation (H₂, Pd/C in ethanol at room temperature) or chemical reduction using iron powder with ammonium chloride in ethanol/water are expected to selectively reduce the nitro group to an amine while leaving the aryl C–F bonds intact. This provides 5-amino-2,4-difluorophenol as a valuable aniline intermediate. Specific conditions and yields should be validated experimentally and referenced against primary literature.

References

1. Aladdin Scientific. Product Information and Certificate of Analysis: 2,4-Difluoro-5-nitrophenol, SKU D586424. Aladdin Scientific, Shanghai.
2. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992. (General reference for nucleophilic aromatic substitution.)
3. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (Textbook reference for aromatic C–F reactivity and nitro group reduction.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.