Para Fluoro Nitro Benzene
A high-purity fluorinated nitroaromatic supplied as the precursor to 4-fluoroaniline and as an activated electrophile for pharmaceutical and agrochemical synthesis.
What is Para Fluoro Nitro Benzene?
Para Fluoro Nitro Benzene — PFNB, or 4-fluoronitrobenzene — is a pale yellow liquid that solidifies to a low-melting solid in a cool store. It carries a fluorine directly opposite a nitro group.
It serves two distinct roles. Reduced, it becomes 4-fluoroaniline, one of the most widely used fluorinated building blocks in drug and crop-protection chemistry. Used as it is, the nitro group activates the fluorine toward nucleophilic aromatic substitution, so amines and alkoxides displace it under mild conditions.
At Chelora Chemicals, PFNB is distilled to high assay with isomer content and moisture controlled, since impurities at this stage carry through both the reduction and the substitution routes.
- Appearance
- Pale yellow liquid or low-melting solid
- Odour
- Faint aromatic
- Solubility
- Insoluble in water; soluble in most organic solvents
- Function
- Chemical intermediate
- Grade
- High purity
Formula diagram
Nitro group with an activated fluorine in the para position
- Molecular formulaC6H4FNO2
- Molecular weight141.10 g/mol
- IUPAC name1-Fluoro-4-nitrobenzene
- Functional groupsNitro, aryl fluoride
- CAS number350-46-9
Technical product information
Standard specification for Chelora Chemicals' high-purity intermediate Para Fluoro Nitro Benzene. Custom-grade and bulk specifications are available on request.
| Chemical name | Para Fluoro Nitro Benzene |
|---|---|
| Synonyms | PFNB, 4-Fluoronitrobenzene, p-Fluoronitrobenzene |
| CAS number | 350-46-9 |
| Molecular formula | C6H4FNO2 |
| Molecular weight | 141.10 g/mol |
| Assay (GC purity) | ≥ 99.5% |
| Appearance | Pale yellow liquid or low-melting solid |
| Melting point | 21–25°C |
| Boiling point | 205°C |
| Density (25°C) | 1.32–1.34 g/cm³ |
| Flash point | > 90°C (closed cup) |
| Isomer content | ≤ 0.3% |
| Water content | ≤ 0.1% |
| Packaging | 250 kg drums, 1000 kg IBC |
| Shelf life | 24 months in sealed original packaging |
Applications of Para Fluoro Nitro Benzene
4-Fluoroaniline production
Hydrogenated to 4-fluoroaniline, a core building block for fluorinated pharmaceuticals and agrochemicals.
Pharmaceutical intermediates
Used directly as an activated electrophile in API and development compound synthesis.
Nucleophilic substitution routes
Amines, alkoxides, and thiolates displace the fluorine under mild conditions to give substituted nitroaromatics.
Agrochemical synthesis
Introduces a fluorinated aromatic fragment into crop-protection actives.
Liquid crystal materials
Feeds fluorinated intermediates used in display material manufacture.
Fine chemicals
Supplied as a research and custom-synthesis building block.
Why choose Chelora Chemicals
Every batch of Para Fluoro Nitro Benzene is manufactured, tested, and documented to a standard that formulators and process chemists can build on with confidence — from first sample to full production volume.
Consistent purity
GC assay controlled at ≥99.5% with isomer content and low moisture verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Flexible volumes
From 250 kg drums to IBC quantities, with samples for development work.
Technical support
Process, handling, and compliance guidance from our chemistry team.
Storage and guidelines
- 01Store in tightly sealed original containers in a cool, dry, well-ventilated store.
- 02Expect the product to solidify below about 21°C; warm gently and evenly before transfer.
- 03Keep away from heat, sparks, open flame, and direct sunlight.
- 04Protect from moisture, which reduces yield in downstream substitution chemistry.
- 05Segregate from strong bases, amines, reducing agents, and strong oxidising agents.
- 06Use compatible containers: glass, stainless steel, or lined steel, and bund all bulk storage.
Handling precautions
PFNB is toxic by inhalation, ingestion, and skin absorption. It is for industrial use by trained personnel only.
Nitroaromatics are absorbed through intact skin and can affect the blood by forming methaemoglobin. Chemical-resistant gloves, coveralls, and eye protection are required.
Reaction with amines and other nucleophiles is exothermic and can accelerate sharply at scale. Substitution chemistry using this product needs its own thermal risk assessment and controlled addition.
Nitroaromatics can decompose exothermically at elevated temperature, and contact with strong bases or reducing agents can be violent. Avoid overheating during warming, drying, or distillation.
Refer to the full Safety Data Sheet for exposure limits, spill response, and first-aid measures before use.
Frequently asked questions
What is Para Fluoro Nitro Benzene used for?
Two things. It is hydrogenated to 4-fluoroaniline, and it is used directly as an activated electrophile where a nucleophile displaces the fluorine to build a substituted nitroaromatic.
Why is the fluorine reactive here when aryl fluorine is normally inert?
The para nitro group withdraws electron density and stabilises the intermediate formed when a nucleophile attacks the ring. Under that activation fluorine is actually the best leaving group of the halogens for this reaction type, which is the opposite of the usual order.
What is the relationship between PFNB and PFA?
PFNB is the nitro compound; 4-fluoroaniline is what you get by reducing it. Both are commonly supplied, and the isomer purity of PFNB sets the ceiling on the purity of the amine.
Is it a liquid or a solid?
It depends on the temperature. The melting point is around 21–25°C, so drums may arrive solid in winter and liquid in summer. Warm gently and evenly before transfer rather than with a localised heat source.
Is it soluble in water?
No. It is practically insoluble in water and readily soluble in DMF, DMSO, acetonitrile, THF, alcohols, and aromatic solvents.
Why is water content specified so tightly?
Residual water competes with the intended nucleophile and consumes base in substitution chemistry, reducing yield. Low, consistent moisture is a functional requirement rather than a cosmetic one.
What purity do you supply?
Standard grade is supplied at a minimum GC assay of 99.5% with isomer content at or below 0.3% and water at or below 0.1%. Tighter specifications can be manufactured for pharmaceutical intermediate use.
What packaging sizes are available?
250 kg drums and 1000 kg IBCs, with laboratory and pilot samples for development and qualification work.
What are the main process safety concerns?
Two: substitution with amines is exothermic and can run away if addition is too fast at scale, and nitroaromatics can decompose exothermically if overheated during warming or work-up. Both need documented thermal assessment.
Is PFNB hazardous?
Yes. It is acutely toxic by several routes, absorbed through skin, and hazardous to aquatic life. Trained personnel, engineering controls, and full PPE are required per the Safety Data Sheet.
Do you provide a Certificate of Analysis?
Yes. Every batch is dispatched with a Certificate of Analysis and Safety Data Sheet covering GC assay, isomer content, melting range, density, water content, and appearance.