Para Fluoroaniline
Para Fluoroaniline — PFA or 4-fluoroaniline — is the workhorse way to get a 4-fluorophenyl group onto a molecule. Fluorine at the para position changes metabolic stability, lipophilicity and binding, which is why this aniline turns up again and again in modern pharmaceutical and agrochemical synthesis.
Chelora Chemicals supplies PFA to API manufacturers, agrochemical producers and fine chemical plants worldwide, in jerricans, drums and IBC quantities, with a batch COA and GHS safety data sheet on every consignment.
Product identity
- CAS Number
- 371-40-4
- IUPAC name
- 4-Fluoroaniline
- Molecular formula
- C6H6FN
- Molecular weight
- 111.12 g/mol
- EC / EINECS
- 206-745-0
- MDL number
- MFCD00007768
- SMILES
- Nc1ccc(F)cc1
- HS Code
- 2921 42*
* Confirm the exact HS heading with your customs broker — classification of halogenated aniline derivatives varies between destination tariffs.
What Para Fluoroaniline is used for
Para Fluoroaniline is an aniline carrying a single fluorine atom para to the amino group. That one substitution is the whole commercial point. Fluorine is small enough to sit almost anywhere a hydrogen would, but its electronegativity blocks the metabolic oxidation that would otherwise happen at that position, shifts the pKa of the amine and nudges lipophilicity. In drug and agrochemical design those are exactly the properties you want to tune — which is why the 4-fluorophenyl fragment appears so widely in modern actives.
In practice PFA is a captive intermediate: plants buy it to acylate, condense, or carry into a heterocyclic ring system. The critical thing is that the fluorine arrives already installed. Fluorinating an aromatic ring on your own site is hazardous, capital-intensive chemistry; buying the fluorinated aniline lets you start one step past that problem.
Why the isomer matters
The three fluoroaniline isomers are genuinely different molecules, and in pharmaceutical work a substitution is not a shade problem — it is a failed batch and a regulatory one:
- 4-Fluoroaniline (CAS 371-40-4) — this product. Fluorine para to the amine. The most widely used of the three.
- 2-Fluoroaniline (CAS 348-54-9) — the ortho isomer. Different steric and electronic profile; used where ring geometry demands it.
- 3-Fluoroaniline (CAS 372-19-0) — the meta isomer, with its own set of heterocyclic routes.
If your purchase order simply says "fluoroaniline", quote us the CAS number and we will confirm the correct material before the order is placed. We supply the sister isomers as well, so there is nothing to gain from guessing.
Appearance and handling character
PFA ships as a clear, colourless to pale yellow or amber mobile liquid with the pungent, penetrating odour typical of anilines. It is only slightly soluble in water and slightly denser than it, so a spill will sink and pool rather than float — relevant both for bund design and for spill response. Like all primary aromatic amines it darkens on exposure to air and light, drifting from water-white to yellow and then amber. That drift is cosmetic in most routes, but if your process or your finished intermediate is colour-specified, say so and we will ship under nitrogen blanket.
| Parameter | Typical value |
|---|---|
| Appearance | Clear, colourless to amber liquid |
| Assay (GC) | 99.0% min |
| Moisture (KF) | 0.2% max |
| Colour (APHA) | Reported per batch |
| Total isomeric impurities | 0.5% max |
| Non-volatile residue | Reported per batch |
Important: the figures above are indicative of commercial grade material and are offered for planning only. The batch certificate of analysis is the governing document. If your process demands a tighter assay, a specific isomer limit, a colour ceiling, a residual-solvent profile or a metals limit, send us the specification and we will quote against it rather than against a generic grade.
| Property | Value |
|---|---|
| Physical state | Liquid at ambient |
| Boiling point | ≈ 187 °C @ 760 mmHg |
| Melting / freezing point | ≈ −2 °C |
| Flash point | ≈ 76 °C |
| Relative density | ≈ 1.17 @ 25 °C |
| Refractive index | ≈ 1.539 (nD20) |
| Partition coeff. (log P) | ≈ 1.15 |
| Water solubility | Slightly soluble; sinks |
| Organic solubility | Miscible with alcohols, ketones, aromatic & chlorinated solvents |
Physical constants compiled from public reference data for CAS 371-40-4 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put this molecule to work
PFA is a general-purpose fluorinated building block rather than a single-outlet intermediate. Its volume is spread across pharmaceutical, agrochemical and specialty synthesis.
Pharmaceutical intermediates
The largest outlet. A 4-fluorophenyl group blocks metabolic oxidation at the para position and tunes binding, so it recurs across many API families. PFA is the usual way to install it — by amide formation, N-arylation, or as the amine partner in a heterocyclic ring build.
- Amide, urea and sulfonamide formation
- Quinazoline, quinoline and pyrimidine routes
- Tight isomer and metals limits usually apply
Agrochemical actives
The same logic applies in crop protection: fluorine improves the stability of an active against metabolic and environmental breakdown, and the fluorophenyl fragment appears across several modern insecticide and fungicide classes.
- Benzoylurea and anilide chemistry
- Heterocyclic active ingredient routes
- See our agrochemical intermediate range
Heterocyclic synthesis
As the aniline component in classical ring-forming reactions — Skraup, Doebner–Miller, Niementowski and their modern equivalents — where the fluorine survives the ring build and ends up on the finished heterocycle.
- Quinoline and quinazoline construction
- Benzimidazole and benzoxazole routes
- Fluorine retained through the sequence
Dye & colourant intermediates
Diazotised and coupled as a component in azo chemistry, where the fluorine shifts shade and can improve fastness relative to the unsubstituted aniline without adding the weight a chlorine or bromine brings.
- Azo diazo component
- Shade and fastness modification
- See also 2,5-dichloroaniline
Electronic & performance materials
A building block in liquid crystal intermediates, fluorinated polymers and other performance materials where the carbon–fluorine bond contributes thermal and chemical stability to the finished structure.
- Liquid crystal intermediate synthesis
- Specialty polymer building blocks
- Available in trial and laboratory quantities
Contract & scheduled supply
API and active-ingredient production runs to campaign. Most PFA buyers want quantity released against a production plan rather than in one shipment. We hold inventory and release it to your schedule.
- Annual contracts with scheduled call-off
- Price held across the contract period
- Second source held in reserve
How we supply Para Fluoroaniline
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. We own no fluoroaniline plant — and for a specification-sensitive intermediate feeding regulated downstream chemistry, that independence works in your favour. We are never obliged to push you whatever a captive unit happens to be running that month.
Instead we place your order with whichever qualified producer best matches your assay, your isomer tolerance, your documentation requirements and your delivery window.
We keep a second qualified source on this line. Fluorinated intermediates have a thinner producer base than the chloro- and nitro-anilines, so a single-sourced buyer is more exposed here than almost anywhere else in the aniline range.
- Specification read against the CAS first. We confirm you need 371-40-4 and not the ortho or meta isomer before we quote a price.
- Batch COA shared before dispatch. You approve the assay, moisture and impurity profile against your own spec while the material is still in our warehouse.
- Documentation for regulated chemistry. Where your downstream step is under a quality system, tell us what the file needs and we will confirm up front what the source plant can and cannot issue.
- Pre-shipment samples for qualification. New account or new source, your R&D team runs a lab batch before the full quantity ever moves.
- Nitrogen blanketing on request. Where colour drift matters to your downstream step, we arrange inert-gas headspace in drums and IBCs.
- Trial pack to full container. Start with a 25 kg jerrican and scale to contracted drum or IBC supply as your campaign firms up.
- Export machinery handled in-house. Hazard classification, UN-approved packing, labelling, freight booking and customs paperwork are ours to manage.
Packed the way your plant receives it
Pack format drives your landed cost and your handling effort. Tell us how the material will be decanted at your end and we will quote the format that suits your operation — not just the one that suits ours.
HDPE jerricans
UN-certified jerricans, palletised and shrink-wrapped. The default for pilot campaigns, laboratory scale-up and plants charging small batch quantities.
MS & HDPE drums
UN-certified drums, palletised and shrink-wrapped. The workhorse format for commercial supply. Nitrogen headspace available on request where colour matters.
IBC totes
Caged intermediate bulk containers for higher-volume users — fewer handling movements, faster decanting and less drum disposal at your end.
Samples & trial packs
Laboratory samples and pilot quantities dispatched by courier so your R&D team can qualify the grade before committing to campaign volume.
Incoterms to suit you
Quoted on the Incoterm your purchasing team works to. Ocean, air and road freight arranged end-to-end with documentation filed before booking.
Campaign despatch
Active-ingredient production runs to campaign. We hold contracted quantity and release it against your production calendar instead of landing it all at once.
Handle this as a toxic, absorbable amine
PFA is not a benign solvent. Like the halogenated anilines generally, it is acutely toxic by all three routes and readily absorbed through intact skin — and being a mobile liquid, it wets skin and clothing far more efficiently than a solid does. The summary below is orientation only — the safety data sheet supplied with your consignment is the authoritative document and should govern your risk assessment, PPE selection and emergency planning.
Classified hazards
H301Toxic if swallowed.H311Toxic in contact with skin.H331Toxic if inhaled.H315Causes skin irritation.H319Causes serious eye irritation.
Hazard statements reflect the GHS classification commonly published for CAS 371-40-4. Supplier classifications may differ in detail and some add an aquatic hazard statement; always read the SDS issued with your specific batch.
Spill & emergency orientation
Plan your response before the drum arrives, not after it leaks. The points below are orientation for your emergency planners — sections 4, 5 and 6 of the SDS are the authoritative instructions and should be posted at the point of use.
- Contain, do not flush. Dyke the spill and absorb with sand or inert absorbent. The liquid is denser than water and will pool at the low point of a bund rather than float.
- Treat vapour as the acute risk. Evacuate and ventilate before approaching a large spill; use self-contained breathing apparatus in confined or poorly ventilated areas.
- Assume skin absorption. A liquid aniline wets clothing thoroughly and keeps delivering dose — remove contaminated clothing immediately and wash the skin thoroughly.
- Have the SDS with the casualty. Anilines can cause methaemoglobinaemia, and the treating clinician needs the product identity and CAS number in hand.
- Dispose as regulated waste through a licensed contractor, in line with your local chemical waste regulations.
Storage
- Cool, dry, well-ventilated store, away from direct sunlight and heat sources. Flash point is around 76 °C, so it is not a low-flash solvent — but it will burn.
- Keep containers tightly closed. Air and light drive the yellow-to-amber colour drift typical of anilines. Nitrogen blanketing preserves colour on long storage.
- Segregate from oxidising agents, strong acids and acid chlorides. As a primary aromatic amine it reacts exothermically with acylating and oxidising reagents.
- Bunded storage with a sealed floor. The liquid sinks in water, so containment and a recoverable low point matter more than dilution in a spill scenario.
- Shelf life is typically 12–24 months in sealed original packing under these conditions. Re-assay before use after long storage.
Handling & PPE
- Skin protection is the priority. Fluoroanilines are absorbed through intact skin — chemical-resistant gloves and coveralls, not just splash protection, and glove breakthrough data checked against the actual contact time.
- Engineering controls first. Handle in closed transfer systems or under local exhaust ventilation; the pungent odour is a warning, not a safe exposure indicator.
- Respiratory protection where vapour or aerosol may be generated, per your own exposure assessment.
- Eye protection and an accessible eyewash and safety shower at all transfer points — H319 applies.
- Never discharge to drain or watercourse. Collect spills with inert absorbent and dispose of them as regulated chemical waste.
Transport
PFA moves as regulated cargo. We classify each consignment, apply UN-approved packaging and labelling, and file the dangerous-goods declaration before the booking is made. The applicable UN number, class and packing group are stated on your shipping documents and SDS — ask us for the current DG paperwork when you plan the shipment.
What travels with every consignment
A chemical shipment is only as good as the file that travels with it — and for material feeding regulated downstream chemistry, the file is half the purchase.
Certificate of Analysis
Batch-specific assay by GC, moisture by Karl Fischer, appearance, colour and impurity profile — checked against your purchase specification before we release the goods.
GHS Safety Data Sheet
Full 16-section SDS in GHS format covering hazards, exposure controls, handling, storage, spill response, toxicology and disposal — issued in the language your destination requires.
Dangerous Goods Declaration
UN number, hazard class, packing group and IMDG or IATA declaration prepared and filed before the container is booked, with correctly marked and labelled packaging.
Certificate of Origin
Chamber-attested where required, plus preferential-origin forms where a trade agreement gives your import duty relief at the destination.
Third-party inspection
SGS, Intertek or Bureau Veritas sampling and inspection arranged on request before loading, giving you independent verification of what actually ships.
Retained & pre-shipment samples
Pre-shipment samples carry the same COA as the commercial lot, so what your laboratory qualifies is exactly what arrives. Retention samples held against the batch.
Why the fluorine is worth paying for
Understanding what the fluorine does downstream explains why this aniline costs more than its chlorinated cousins — and why buying it fluorinated is usually cheaper than fluorinating it yourself. The route below is the general industrial pattern, not a process disclosure.
Start with the fluorine installed
Aromatic fluorination is hazardous, capital-intensive chemistry. Buying PFA means the difficult step is already behind you and your plant starts from a stable, storable liquid.
Functionalise the nitrogen
Acylation, sulfonylation, urea formation, reductive amination or N-arylation — the amine is the reactive handle, and the fluorine simply rides along untouched.
Build the ring system
Where the target is heterocyclic, the aniline is condensed and cyclised into a quinoline, quinazoline or benzimidazole core carrying the fluorine at a defined position.
Purify to grade
The intermediate or active is crystallised and dried to the purity the end market demands — which, for a regulated API chain, includes impurity limits traceable to this feed.
Why aniline quality carries through the whole route
Every one of those steps acts on the nitrogen. Anything in the feed that competes for that nitrogen, or that carries its own reactive functionality, follows the material down the line — and in regulated chemistry it does not just cost yield, it has to be explained:
- Isomeric fluoroanilines react in parallel and give structurally similar products that are difficult to separate and awkward to justify in an impurity profile.
- Residual water hydrolyses acid chlorides and anhydrides, consuming expensive reagent and generating acid in the batch.
- Oxidation products — the coloured species responsible for the amber drift — can carry into the intermediate and show as colour in an otherwise white solid.
- Heavy residues and metals concentrate through the sequence and, in an API chain, become a specification question rather than merely a yield one.
That chain of consequences is the reason we quote against your written specification rather than a generic "99% technical" grade, and the reason the batch COA is shared for approval before dispatch rather than sent with the invoice.
| Intermediate | Fragment installed |
|---|---|
| Para Fluoroaniline CAS 371-40-4 — this product | 4-Fluorophenyl Blocks para-position metabolism |
| Para Chloroaniline CAS 106-47-8 | 4-Chlorophenyl Heavier, more lipophilic |
| Ortho / Meta Fluoroaniline CAS 348-54-9 / 372-19-0 | 2- and 3-Fluorophenyl Different ring geometry |
If your route calls for a different halogen or a different position, we supply those as well — see para chloroaniline and the full intermediate range. Send the CAS number and we will confirm the correct material before quoting.
What actually moves the price of this intermediate
PFA is not a commodity with a screen price. Knowing what drives the quote helps you time a purchase and read whether an offer is realistic.
Fluorination cost
Installing aromatic fluorine is the expensive step, and it dominates the price. Fluorine chemistry has a narrower producer base, tighter effluent obligations and higher capital intensity than chlorination.
- Structurally priced above chloroanilines
- Fluorspar and HF chain feeds the cost
- Effluent compliance is a real cost element
Thin producer base
Fewer plants make this than make the chlorinated anilines. A single turnaround has a proportionally larger effect on availability, and lead times stretch faster when one unit goes down.
- We hold a second qualified source on this line
- Qualify the alternate before you need it
- Ask us about dual-source contracts
Specification tier
Pharmaceutical-chain material with tight isomer, metals and residual-solvent limits prices well above technical grade destined for general synthesis. Paying for a spec you do not need is a common and avoidable cost.
- Tell us the end use, not just the purity
- Technical grade suits non-regulated outlets
- We will say when a tighter spec is unnecessary
Campaign timing
API and active-ingredient campaigns are scheduled months ahead, and so is the intermediate that feeds them. Late enquiries compete for the same limited capacity as everyone else's late enquiries.
- Quote early for campaign quantity
- Spot buying costs materially more
- Contracted call-off smooths the exposure
Pack format
Cost per kilo falls from jerricans to drums to IBCs. If your receiving system can take a tote, the saving over a campaign usually dwarfs the handling change — and it cuts operator contact with a skin-absorbable liquid.
- Jerricans carry the highest packing cost
- IBC is cheapest per kilo at volume
- Drum disposal is a hidden cost at your end
Freight & DG surcharges
This is regulated cargo, so ocean freight carries a hazardous surcharge and space is tighter than for general cargo. Destination and Incoterm move landed cost as much as the ex-works price does.
- Compare on landed cost, not ex-works
- DG space books out ahead of peak season
- We quote FOB, CIF, CFR or DDP as you prefer
| If your end use is… | Specify |
|---|---|
| Pharmaceutical chain | High assay, tight isomer limit, metals and residual solvents reported |
| Agrochemical actives | High assay with controlled moisture |
| Heterocyclic synthesis | Low isomer content; heavy-ends limit worth setting |
| Dye & colourant work | Colour ceiling usually matters more than assay |
| Laboratory / R&D | Small pack, high purity, full analytical pack |
Not sure which column you are in? Describe the reaction you are running and our technical desk will recommend the grade — including telling you when a cheaper specification would do the job just as well.
Support that goes beyond shipping the drum
What our technical desk will do
- Match a grade to your reaction. Tell us the step you are running and we will recommend the specification — and say so plainly when a tighter, costlier grade would add nothing.
- Be straight about documentation. Where your quality system needs particular declarations from the source plant, we confirm before you order what can and cannot be issued rather than discovering it at audit.
- Suggest a workable substitute. If PFA is tight or the price has moved against you, we will tell you whether an alternative aniline fits your route rather than simply reporting no stock.
- Review your specification before it goes into a contract, so you are not locked into a limit that no plant can consistently hit.
Regulatory & compliance notes
- Import controls vary by destination. Fluorinated intermediates attract registration, licensing or end-use declaration requirements in some jurisdictions. We check the destination rules before quoting, not after you have raised the PO.
- Chemical inventory listings differ between regions. Confirm your obligations under the applicable inventory regime for your import volume — we will supply the identity data you need for that filing.
- Downstream quality obligations for API chains sit with you, and the further upstream a material is, the more varied the expectations. Tell us early what your file needs.
- Dangerous goods documentation is prepared by our export desk and filed before booking, so the consignment is not held at origin for paperwork.
None of the above is legal advice — your own regulatory affairs team owns the final compliance position for your import. What we commit to is giving you accurate product identity data and complete documentation to work from.
From enquiry to delivered drum
Send the specification
Product name or CAS 371-40-4, the assay and impurity limits you work to, quantity, pack preference and destination port.
Receive a firm quote
Pricing, lead time, packing and Incoterm confirmed in writing within 24 hours — our sourcing desk is staffed around the clock.
Qualify and approve
Sample dispatched if you are qualifying a new source. Batch COA shared for your approval before the material is released.
Ship and track
DG classification filed, freight booked, export documents issued, and the consignment tracked through transit and clearance to your plant.
Often bought alongside this grade
Consolidate several intermediates onto one shipment and one invoice. These are the anilines and aromatics our pharmaceutical and agrochemical customers most often order in the same programme.
What buyers ask us about Para Fluoroaniline
Can I substitute the ortho or meta isomer?
Why is this so much more expensive than para chloroaniline?
What purity do you normally supply?
What is the minimum order quantity?
Can I get a sample before committing to an order?
How long does delivery take?
Why does the liquid darken in storage? Is the batch off-spec?
How should we store it, and what is the shelf life?
Is this a dangerous good? What paperwork comes with it?
- Batch certificate of analysis
- GHS-format safety data sheet
- Dangerous-goods declaration with UN number, class and packing group
- Commercial invoice, packing list and bill of lading or airway bill
- Certificate of origin and any destination-specific forms
Do you supply to my country?
Do you manufacture this yourself?
Can you hold stock against a campaign plan?
Request pricing on Para Fluoroaniline
Send your required assay, quantity, pack format and destination port. Our sourcing desk is available 24 hours a day, 7 days a week, and comes back with pricing, lead time and packing options — whether that is a single trial jerrican or a contracted drum programme for the campaign.