2,5-Dichlorophenol
2,5-Dichlorophenol — 2,5-DCP — is a dichlorinated phenol carrying one chlorine ortho to the hydroxyl group and a second on the far side of the ring. It is a long-established building block for dye and pigment intermediates, biocide and preservative chemistry, and agrochemical and pharmaceutical synthesis, and is also supplied as an analytical reference standard for residue-testing laboratories.
Chelora Chemicals supplies 2,5-DCP to dye houses, biocide formulators, fine chemical manufacturers and analytical laboratories worldwide, in bags, drums and container quantities, with a batch COA and GHS safety data sheet on every consignment.
Product identity
- CAS Number
- 583-78-8
- IUPAC name
- 2,5-Dichlorophenol
- Molecular formula
- C6H4Cl2O
- Molecular weight
- 163.00 g/mol
- EC / EINECS
- 209-520-4
- MDL number
- MFCD00002174
- SMILES
- Oc1cc(Cl)ccc1Cl
- HS Code
- 2908 19*
* Confirm the exact HS heading with your customs broker — classification of halogenated phenol derivatives varies between destination tariffs.
What 2,5-Dichlorophenol is used for
2,5-Dichlorophenol is a phenol carrying two chlorine substituents in an asymmetric pattern — one ortho to the hydroxyl group, the other on the opposite side of the ring. That asymmetry gives the molecule a distinct electronic profile from the more familiar 2,4-isomer, and it is exactly that distinction that governs which downstream chemistry it is chosen for. The phenolic OH remains the reactive handle: it etherifies, esterifies, diazotises after conversion to the corresponding amine, and couples into azo and biguanide-type structures much as other chlorophenols do.
In practice 2,5-DCP is a captive and semi-captive intermediate. Plants buy it to build dye and pigment couplers, to synthesise chlorinated preservative and biocide actives, or to run it into agrochemical and pharmaceutical side chains. Analytical laboratories also draw on it in small pack sizes as a calibration and reference standard, since chlorophenols of this kind are tracked as environmental and residue markers.
Why the isomer matters
The chlorophenol family covers a wide range of substitution patterns, and a mix-up between isomers is not recoverable once the material has gone into a batch:
- 2,5-Dichlorophenol (CAS 583-78-8) — this product. One chlorine ortho to the hydroxyl, one on the far side of the ring.
- 2,4-Dichlorophenol — the more common symmetric-looking isomer, widely used in its own right across dye, biocide and herbicide chemistry.
- 4-Chlorophenol and 2-chlorophenol — the mono-chlorinated parents, each with a separate reactivity profile and use pattern.
If your purchase order simply says "dichlorophenol", quote us the CAS number and we will confirm the correct material before the order is placed. We source the wider chlorophenol family as well — see our full intermediate range for related grades.
Appearance and handling character
2,5-DCP ships as a white to light yellow or light brown crystalline solid melting in the mid-50s °C — solid and stable in a temperate store, but close enough to typical warehouse temperatures in a hot climate that a poorly ventilated container can soften or partially cake in transit. It is only sparingly soluble in water but dissolves readily in alcohols, ethers, benzene and petroleum ether. Like other phenols it darkens slowly on exposure to air and light. It also carries a very low taste-and-odour threshold in water, which is worth knowing before it planning storage near any water-sensitive process — read the safety section below before planning your handling.
| Parameter | Typical value |
|---|---|
| Appearance | White to light yellow / light brown crystals |
| Assay (GC) | 98.0% min |
| Moisture (KF) | 0.5% max |
| Melting range | 54 – 59 °C |
| Total isomeric impurities | 1.5% 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 pesticide-analytical grade or a controlled moisture figure, send us the specification and we will quote against it rather than against a generic grade.
| Property | Value |
|---|---|
| Physical state | Crystalline solid at ambient |
| Melting point | ≈ 57 °C (54 – 59 °C) |
| Boiling point | ≈ 211 °C @ 760 mmHg |
| Flash point | ≈ 100 °C |
| Relative density | ≈ 1.34 (estimate) |
| Partition coeff. (log P) | ≈ 3.06 |
| pKa | ≈ 7.5 |
| Water solubility | Sparingly soluble (≈ 2 – 3 g/L) |
| Organic solubility | Soluble in alcohols, ethers, benzene, petroleum ether |
| Odour | Phenolic; very low detection threshold in water |
Physical constants compiled from public reference data for CAS 583-78-8 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put this molecule to work
2,5-DCP is a general-purpose chlorophenol rather than a single-outlet one. Its volume is spread across colour chemistry, biocide synthesis, agrochemical and pharmaceutical intermediates, and analytical reference use.
Dye & pigment intermediates
2,5-DCP is converted to its corresponding chloroaniline or used directly as a coupling component in azo dye and pigment chemistry, where its substitution pattern shifts shade and fastness relative to the 2,4-isomer.
- Coupling component in azo chemistry
- Isomer purity shows up directly as off-shade
- See our full colourant intermediate range
Biocides & preservatives
Chlorophenols are a long-established precursor family for industrial preservatives and antimicrobial actives. 2,5-DCP is used in the synthesis of chlorinated preservative and disinfectant intermediates for industrial and wood-protection applications.
- Chlorinated preservative synthesis
- Industrial biocide intermediate chemistry
- Tight isomer and colour limits usually apply
Agrochemical intermediates
The chlorophenol ring is a recurring fragment in herbicide and fungicide chemistry, reached either by O-alkylation of the phenol or by further functionalisation of the ring.
- O-alkylation to ether-linked actives
- Ring chemistry for fungicide intermediates
- See our agrochemical intermediate range
Pharmaceutical intermediates
A chlorophenol building block for amide, ether and heterocyclic ring construction across several established drug families, where the two chlorines are retained as part of the final pharmacophore or used as leaving groups.
- O-alkylation and ether formation
- Heterocyclic ring construction
- See our pharmaceutical intermediate range
Analytical reference standards
Because chlorophenols are tracked as environmental contaminants and pesticide metabolites, 2,5-DCP is supplied in small, high-purity packs as a calibration and reference standard for residue-testing and environmental laboratories.
- High-purity analytical-grade packs
- Small pack sizes from laboratory quantities
- Certificate of analysis with every pack
Contract & scheduled supply
Dye, biocide and agrochemical plants run to campaign, not to a calendar month. Most 2,5-DCP buyers want tonnage 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 2,5-Dichlorophenol
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. We own no chlorophenol plant — and for a specification-sensitive intermediate like this one, 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 colour requirement and your delivery window.
We keep a second qualified source on this line. When a plant goes down for maintenance, or a monsoon disrupts a road corridor, your campaign switches source rather than stalling.
- Specification read against the CAS first. We confirm you need 583-78-8 and not the 2,4-isomer or a mono-chlorinated grade, before we quote a price.
- Batch COA shared before dispatch. You approve the assay, moisture, colour and impurity profile against your own spec while the material is still in our warehouse.
- Hazard status stated up front. This material is corrosive and toxic and carries an aquatic hazard classification, and we say so at enquiry stage — not in the small print of a document pack that arrives with the goods.
- Pre-shipment samples for qualification. New account or new source, your R&D or QC team runs a lab batch before the full quantity ever moves.
- Packing chosen for your climate. With a melting point in the mid-50s °C, pack format and stowage matter on a tropical routing. We plan both with you.
- Export machinery handled in-house. Hazard classification, UN-approved packing, labelling, freight booking and customs paperwork are ours to manage.
- Consolidation onto one bill of lading. Ship 2,5-DCP alongside other intermediates from our range — one invoice, one shipment, one counterparty.
Packed the way your plant receives it
Pack format drives your landed cost and your handling effort — and for a corrosive phenol, it also drives operator exposure. Tell us how it will be charged at your end and we will quote the format that suits your operation.
Multi-wall paper & PE bags
Laminated multi-wall bags with an inner liner, palletised and shrink-wrapped. The default for LCL movements and for plants charging batch-wise by hand.
Fibre & HDPE drums
UN-certified drums with liner for longer sea transits and humid destinations. Better protection against moisture pick-up, colour drift and caking than bagged material.
Jumbo / FIBC bags
Bulk bags with liner for high-volume users with mechanical charging. Fewer handling movements, lower operator contact and materially lower packing cost per kilo.
Analytical & trial packs
High-purity analytical-grade material in laboratory pack sizes, dispatched by courier for reference standards, residue-testing and trial qualification work.
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
Dye, biocide and agrochemical production runs to campaign. We hold contracted tonnage and release it against your production calendar instead of landing it all at once.
Handle this as a corrosive, aquatic-hazard phenol
This is the point on the page that matters most. 2,5-Dichlorophenol is harmful if swallowed, toxic in contact with skin, causes severe skin burns and eye damage, and is toxic to aquatic life with long-lasting effects. Supplier classifications for this CAS number vary slightly in detail between corrosive-skin-burn labelling and an irritant-plus-respiratory labelling, depending on the grade and formulation tested — the summary below is orientation only, and 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
H302Harmful if swallowed.H311Toxic in contact with skin.H314Causes severe skin burns and eye damage.H411Toxic to aquatic life with long lasting effects.
Hazard statements reflect the harmonised GHS classification commonly published for CAS 583-78-8. Some analytical-grade batches carry an alternative classification set (H302, H315, H319, H335 — irritant rather than corrosive); always read the SDS issued with your specific batch and treat the more conservative reading as your starting point for handling.
Spill & emergency orientation
Plan your response before the pallet arrives, not after a bag splits. 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.
- Sweep, do not hose. The material is toxic to aquatic life and has a very low odour threshold in water. Collect spilled solid mechanically into a labelled container; never wash it to a drain.
- Suppress dust. Dry sweeping of a fine crystalline solid generates an inhalable aerosol — use vacuum collection or dampen carefully in line with the SDS.
- Treat as a corrosive splash risk. Contaminated clothing and gloves are a continuing exposure route — remove them immediately and wash the skin thoroughly with water.
- Have the SDS with the casualty. Chlorophenols can cause systemic effects beyond the initial burn, and the treating clinician needs the product identity and CAS number in hand.
- Contain, do not dilute. Because the aquatic odour and toxicity threshold is so low, even small quantities reaching a watercourse can trigger a reportable event — contain first, then call for guidance.
Storage
- Cool, dry, well-ventilated store, away from direct sunlight and heat sources. The melting point is only in the mid-50s °C, so an uncooled store in a hot climate can soften the contents into a partial cake.
- Keep containers tightly closed. Air and light drive the slow colour drift typical of phenols, and an open bag also picks up moisture.
- Segregate from oxidising agents, strong bases and acid chlorides. As a phenol it reacts readily with acylating and oxidising reagents and is incompatible with strong alkalis.
- Bunded, spill-contained storage. Given the aquatic hazard classification, a bunded floor that prevents run-off to drains is part of the control, not an administrative nicety.
- Shelf life is typically 12–24 months in sealed original packing under these conditions. Re-assay before use after long storage.
Handling & PPE
- Skin and eye protection are the priority. Chlorophenols are absorbed through intact skin and can cause severe burns — chemical-resistant gloves, coveralls and a face shield or chemical goggles, not just splash protection.
- Respiratory protection where dust may be generated — particularly when breaking a caked drum or transferring bulk material — per your own exposure assessment.
- Design exposure out where you can. Closed transfer and mechanical charging reduce both skin contact and the chance of a spill reaching a drain.
- Health surveillance where indicated. Where local regulation calls for it on corrosive or toxic phenols, your occupational health provider and EHS function own the programme detail.
- Never discharge to drain or watercourse. H411 applies — collect spills as solid waste and dispose of them as regulated chemical waste.
Transport
2,5-DCP moves as regulated cargo, typically under UN 2020 (toxic solid, organic, n.o.s. — Class 6.1, Packing Group III on the reference safety data). 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. Verifying what the source plant sends is precisely the work you are buying from a supplier.
Certificate of Analysis
Batch-specific assay by GC, moisture by Karl Fischer, appearance, melting range 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.
The two routes onto this ring
Almost everything made from 2,5-DCP starts from one of two starting points: direct chlorination of phenol, or diazotisation of the corresponding dichloroaniline. Which route a given producer uses shapes the isomer and colour profile you receive. The routes below are the general industrial pattern, not a process disclosure.
Start with the ring
Phenol or the corresponding chloroaniline provides the aromatic core, with the hydroxyl or amine group directing where chlorine will substitute.
Door one — chlorinate
Controlled chlorination of phenol with a catalyst gives a mixture of chlorophenol isomers, which are separated by fractional distillation and crystallisation to isolate the 2,5-pattern.
Door two — diazotise
2,5-Dichloroaniline is diazotised and hydrolysed to give the phenol directly, a route favoured when isomer purity is the priority over throughput.
Finish to grade
The crude product is crystallised, washed and dried, then standardised or purified to whatever the end market demands — colour target, agro spec or analytical-grade limit.
Why phenol quality carries through the whole route
Both doors act on the ring position. Anything in the feed that competes for that position, or that carries its own reactive functionality, follows the material down the line:
- Isomeric chlorophenols chlorinate or diazotise in parallel and give structurally similar products — an off-shade chromophore in colour work, a hard-to-separate by-product in biocide work.
- Residual water is tolerable in some routes but interferes with acylation and ether-forming chemistry downstream, wasting reagent and reducing yield.
- Oxidation products — the coloured species responsible for the slow brown drift — dull a finished shade and can show as colour in an otherwise white solid.
- Heavy residues concentrate in the still bottoms and reduce the number of passes you get from a distillation or crystallisation train.
That chain of consequences is the reason we quote against your written specification rather than a generic "98% technical" grade, and the reason the batch COA is shared for approval before dispatch rather than sent with the invoice.
| Intermediate | Principal outlet |
|---|---|
| 2,5-Dichlorophenol CAS 583-78-8 — this product | Dye & pigment couplers Biocide intermediates Analytical reference standards |
| 2,4-Dichlorophenol Sister isomer | Herbicide ether intermediates Dye chemistry Preservative synthesis |
| 4-Chlorophenol Mono-chlorinated parent | Fine chemical intermediates Resin & polymer chemistry |
If your route calls for one of the others, we supply those as well — see our full chlorophenol range. Send the CAS number and we will confirm the correct material before quoting.
What actually moves the price of this intermediate
2,5-DCP 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.
Multiple demand cycles
Dye, biocide and agrochemical demand pull on the same chlorophenol at different times of year, so the market rarely goes quiet in the way a single-outlet intermediate does.
- Quote early for campaign tonnage
- Spot buying at peak costs materially more
- Contracted call-off smooths the exposure
Upstream feedstock
The route back to 2,5-DCP runs through phenol, benzene and chlorine. Movements in benzene, chlorine and energy cost feed through to the chlorophenol within a quarter or so.
- Chlorine and phenol set the floor
- Energy cost weighs on distillation
- We flag feedstock-driven moves in the quote
Regulatory pressure
An aquatic-hazard and corrosivity classification raises the compliance cost of producing, storing and moving this material. Chlorophenols also carry very low regulatory discharge limits because of their taste-and-odour impact on water supplies.
- Handling obligations vary by jurisdiction
- Effluent discharge limits are unusually strict
- We check destination rules before quoting
Pack format
Cost per kilo falls from 25 kg bags to drums to jumbo bags — and with a corrosive solid, bulk bags also cut the number of times an operator opens a pack.
- Small bags carry the highest packing cost
- FIBC is cheapest per kilo at volume
- Less manual handling means less exposure
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
Source availability
A plant turnaround, an environmental inspection or a monsoon disruption can take capacity offline at short notice. Single-sourced buyers feel this hardest.
- We hold a second qualified source on this line
- Qualify the alternate before you need it
- Ask us about dual-source contracts
| If your end use is… | Specify |
|---|---|
| Dye & pigment couplers | Colour ceiling, tight isomer limit, low insolubles |
| Biocide synthesis | High assay with tight isomer and residue limits |
| Agrochemical ether route | High assay with moisture the critical parameter |
| Pharmaceutical chain | Tight isomer limit; metals and residues reported |
| Analytical / 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 bag
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 the hazard profile. We state the corrosivity and aquatic hazard classification at enquiry stage so your EHS team can price the controls into the decision, rather than meeting it for the first time on the label.
- Advise on handling and storage for your site conditions — a bagged store in a Gulf summer is a different problem from one in northern Europe, especially for a solid that softens close to warm ambient temperatures.
- 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
- Aquatic discharge limits are unusually strict. Chlorophenols including this one have an extremely low taste-and-odour threshold in water, and several regulatory regimes set correspondingly low effluent and environmental limits. Confirm what applies at your site before the first delivery.
- Import controls vary by destination. Some jurisdictions apply registration, licensing or end-use declaration requirements to chlorophenol intermediates. 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 article restrictions can apply to certain wood-preservation and consumer applications. Your regulatory team should confirm the finished-article position for the end use you have in mind.
None of the above is legal advice — your own regulatory affairs team owns the final compliance position for your import and your workplace. What we commit to is giving you accurate product identity data, an honest statement of the hazard classification and complete documentation to work from.
From enquiry to delivered pallet
Send the specification
Product name or CAS 583-78-8, 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 chlorophenols and related aromatics our dye, biocide and agrochemical customers most often order in the same programme. Each of the names below is part of our wider product range — browse the full listing or ask us for the specific CAS number you need.
What buyers ask us about 2,5-Dichlorophenol
Is this material corrosive?
Can I use the 2,4-isomer instead?
What purity do you normally supply?
What is the minimum order quantity?
How long does delivery take?
The material arrived caked or partly softened. Is it off-spec?
Why does the solid darken in storage?
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 production plan?
Request pricing on 2,5-Dichlorophenol
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 pack or a contracted container programme for the year.