Ortho Nitro Chloro Benzene
Ortho Nitro Chloro Benzene — ONCB or 2-nitrochlorobenzene — is one of the two nitrochlorobenzene isomers that anchor the world's chlorobenzene-nitration industry. It is the standard route into ortho-phenylenediamine (OPDA), and from there into benzimidazole fungicides, rubber chemicals and corrosion inhibitors, as well as into dyes, pigments and pharmaceutical intermediates through direct reduction or ammonolysis.
Chelora Chemicals supplies ONCB to agrochemical, rubber-chemical and dye manufacturers worldwide, in drums and container quantities, with a batch COA and GHS safety data sheet on every consignment.
Product identity
- CAS Number
- 88-73-3
- IUPAC name
- 1-Chloro-2-nitrobenzene
- Molecular formula
- C6H4ClNO2
- Molecular weight
- 157.56 g/mol
- EC / EINECS
- 201-854-9
- MDL number
- MFCD00007061
- SMILES
- [O-][N+](=O)c1ccccc1Cl
- HS Code
- 2904 20*
* Confirm the exact HS heading with your customs broker — classification of nitrochlorobenzene isomers varies between destination tariffs.
What Ortho Nitro Chloro Benzene is used for
Ortho Nitro Chloro Benzene carries a nitro group and a chlorine on adjacent ring carbons. That ortho relationship is what makes the molecule so useful: the nitro group activates the chlorine toward nucleophilic displacement, so ammonia, methoxide and other nucleophiles will kick the chlorine out under conditions that leave the para isomer largely untouched. It is this displacement chemistry, not the nitro group alone, that decides where ONCB goes.
Chlorobenzene nitration gives a mixture of the ortho and para isomers in roughly comparable quantity, plus a small amount of the meta isomer. Plants that run this nitration separate the isomers by fractional crystallisation and sell — or consume in house — both cuts. This page covers the ortho cut, CAS 88-73-3; see our full product range for the para isomer (para-nitrochlorobenzene, CAS 100-00-5).
Why the isomer matters
Ortho and para nitrochlorobenzene are separate molecules with separate chemistries, and a mix-up is not recoverable once the batch has run:
- 2-Nitrochlorobenzene / ONCB (CAS 88-73-3) — this product. Chlorine activated by an adjacent nitro group; the standard feed for ortho-phenylenediamine.
- 4-Nitrochlorobenzene / PNCB (CAS 100-00-5) — the para isomer, feeding para-phenylenediamine, para-aminophenol and rubber antidegradants through the same style of displacement chemistry.
- 3-Nitrochlorobenzene (CAS 121-73-3) — the minor meta cut, used in smaller volume across dye intermediate chemistry.
If your purchase order simply says "nitrochlorobenzene", quote us the CAS number and we will confirm the correct isomer before the order is placed.
Appearance and handling character
ONCB ships as a yellow crystalline solid, fused mass or, in a warm climate, a yellow liquid — the melting point sits only around 32 °C, so material that left the plant as a solid often arrives at a tropical port as a liquid or a re-solidified cake. It has a faint, characteristic odour, is only slightly soluble in water, and dissolves readily in alcohols, benzene and most common organic solvents. Read the safety section before planning any handling: ONCB is acutely toxic by all three exposure routes and carries an IARC Group 2B classification (possibly carcinogenic to humans), and that should shape your controls from the outset.
| Parameter | Typical value |
|---|---|
| Appearance | Yellow crystals, fused mass or liquid |
| Assay (GC) | 99.5% min |
| Para-isomer content | 0.5% max |
| Moisture (KF) | 0.2% max |
| Melting range | 31 – 34 °C |
| Acidity (as HCl) | 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 isomer limit, a lower acidity ceiling 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 | Yellow crystalline solid / liquid near ambient |
| Melting point | ≈ 32 °C |
| Boiling point | ≈ 246 °C @ 760 mmHg |
| Flash point | ≈ 127 °C |
| Relative density | ≈ 1.35 (25 °C) |
| Vapour pressure | ≈ 0.04 mmHg (25 °C) |
| Water solubility | Slightly soluble (≈ 0.4 g/L) |
| Organic solubility | Soluble in alcohol, benzene, ether & most organic solvents |
| Odour | Faint, characteristic aromatic-nitro odour |
Physical constants compiled from public reference data for CAS 88-73-3 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put this molecule to work
ONCB is a workhorse intermediate rather than a single-outlet one. Its volume is spread across agrochemical, rubber-chemical, dye and pharmaceutical chemistry.
Ortho-phenylenediamine (OPDA)
The signature route. Ammonolysis displaces the activated chlorine to give 2-nitroaniline, which is then reduced to OPDA — the building block for benzimidazole fungicides such as carbendazim, and for a range of heterocyclic and rubber chemicals.
- Ammonolysis then reduction to OPDA
- Feeds benzimidazole fungicide chemistry
- See our agrochemical intermediate range
Rubber chemicals
OPDA and related ortho-diamine intermediates derived from ONCB feed into benzimidazole- and thiazole-type rubber additives, and into corrosion-inhibitor chemistry used in metalworking fluids and coatings.
- Antidegradant and corrosion-inhibitor precursors
- Heterocyclic ring construction from the diamine
- Consistent isomer purity keeps downstream yield stable
Dyes & pigments
Direct reduction of ONCB gives 2-chloroaniline, diazotised and coupled to build azo dyes and pigments. The ortho nitro-chloro pattern also carries through into sulfur-dye and other dye-intermediate chemistry that needs the two groups adjacent.
- Reduction to 2-chloroaniline for azo work
- Sulfur dye intermediate chemistry
- Colour ceiling matters — talk to our technical desk
Pharmaceutical intermediates
Ortho-nitro-chloro and ortho-diamine fragments recur across several established heterocyclic drug families. ONCB is the usual entry point where a fused-ring benzimidazole, quinoxaline or related scaffold is required.
- Route to benzimidazole and quinoxaline scaffolds
- Ammonolysis / reduction sequence, run to your spec
- Available in trial and laboratory quantities
Fine & specialty synthesis
A well-characterised aryl nitro-chloride for custom nucleophilic aromatic substitution work — amines, alkoxides and thiols all displace the activated chlorine under appropriate conditions, giving fast access to a wide range of ortho-substituted nitrobenzenes.
- SNAr chemistry with amine, alkoxide & thiol nucleophiles
- Nitro group retained as a handle for later reduction
- Custom purity and pack size on request
Contract & scheduled supply
Fungicide and rubber-chemical plants run to campaign, not to a calendar month. Most ONCB 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 Ortho Nitro Chloro Benzene
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. We own no nitrochlorobenzene plant — and for a co-produced isomer pair like ONCB and PNCB, that independence matters. We are never obliged to push you whichever cut a captive unit happens to have surplus that month.
Instead we place your order with whichever qualified producer best matches your isomer purity, your assay, your price point and your delivery window.
We keep a second qualified source on this line. When a nitration unit 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 88-73-3 and not the para or meta isomer before we quote a price.
- Batch COA shared before dispatch. You approve the assay, isomer content and moisture against your own spec while the material is still in our warehouse.
- Hazard status stated up front. This material is acutely toxic and carries an IARC 2B 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 team runs a lab batch before the full quantity ever moves.
- Packing chosen for your climate. With a melting point around 32 °C, ONCB can arrive as a liquid on a tropical routing. We plan pack format and stowage with that in mind.
- 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 ONCB alongside other intermediates from our range — one invoice, one shipment, one counterparty.
Packed the way your plant receives it
ONCB can travel as a solid or a liquid depending on ambient temperature, and pack format decides which one arrives. Tell us how your plant charges the reactor and we will quote the format that suits your operation.
MS / HDPE-lined drums
The default format for a material that may arrive fused or liquid. Lined mild-steel or HDPE drums with a bung fitting for direct pump-off, or bunged for solid handling.
Lined bags (solid form)
For destinations that will keep the material solid and want batch-wise manual charging. Laminated bags with an inner liner, palletised and shrink-wrapped.
Bulk liquid movement
For large, repeat-buy contracts, flexitank or ISO tank movement at molten temperature cuts packing cost and handling to a minimum — subject to destination heating and unloading capability.
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
Agrochemical and rubber-chemical 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 an acutely toxic, IARC-listed intermediate
This is the point on the page that matters most. Ortho nitro chloro benzene is acutely toxic by ingestion, skin contact and inhalation, is listed by IARC in Group 2B (possibly carcinogenic to humans), and is toxic to aquatic life. 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, exposure monitoring and emergency planning.
Classified hazards
H301Toxic if swallowed.H311Toxic in contact with skin.H331Toxic if inhaled.H411Toxic to aquatic life with long lasting effects.
Hazard statements reflect the harmonised GHS classification commonly published for CAS 88-73-3. This material is additionally listed by IARC in Group 2B (possibly carcinogenic to humans) — supplier classifications may differ in detail; always read the SDS issued with your specific batch, and treat that entry as one that shapes your controls alongside the acute-toxicity statements.
Spill & emergency orientation
Plan your response before the drum arrives, not after one 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 hose to drain. The material is toxic to aquatic life with long-lasting effects. Bund and collect a liquid spill mechanically into a labelled container.
- Plan for both phases. A drum that arrived solid can be liquid by the time it is opened in a hot store — brief your team on handling ONCB as either a melt or a solid.
- Assume skin absorption. Nitrochlorobenzenes are absorbed through intact skin — contaminated clothing is a continuing exposure route; remove it immediately and wash thoroughly.
- Have the SDS with the casualty. Nitroaromatic exposure can cause methaemoglobinaemia, and the treating clinician needs the product identity and CAS number in hand.
- Record the exposure. Given the IARC 2B listing, many occupational regimes expect an exposure record to be created and retained. That is a decision for your EHS function.
Storage
- Cool, dry, well-ventilated store, below 30 °C where practical, away from direct sunlight and heat sources. The melting point is only around 32 °C, so an uncooled store in a hot climate will keep the material molten.
- Keep containers tightly closed. Limits vapour loss and moisture pick-up, and keeps the assay stable across a long transit.
- Segregate from reducing agents, strong bases and alkali metals. ONCB can react vigorously, and in some conditions explosively, with strong reducing agents and with ammonia under pressure — keep well clear of these classes.
- Access-controlled storage. For an IARC-listed, acutely toxic material, restricting who can reach the store is part of the control, not an administrative nicety.
- Shelf life is typically 24 months in sealed original packing under these conditions. Re-assay before use after long storage.
Handling & PPE
- Design exposure out, do not manage it down. Closed transfer and mechanical charging first, ventilation second, PPE last — especially where the material is handled molten.
- Skin protection is the priority. Nitrochlorobenzenes are absorbed through intact skin — chemical-resistant gloves and coveralls, not just splash protection, and particular care around hot, molten material.
- Respiratory protection where dust or vapour may be generated — particularly when breaking a solidified drum or transferring molten product — per your own exposure assessment.
- Health surveillance and exposure records. Where the IARC 2B listing triggers obligations at your site, your occupational health provider and EHS function own the detail. We flag the classification; the programme is yours to run.
- Never discharge to drain or watercourse. H411 applies — collect spills and dispose of them as regulated chemical waste.
Transport
ONCB moves as regulated cargo (commonly shipped under UN 1578, Class 6.1, Packing Group II, subject to your carrier's classification). We classify each consignment, apply UN-approved packaging and labelling, and file the dangerous-goods declaration before the booking is made — 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, isomer content, moisture and acidity — 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 out of this nitro-chloride
Almost everything made from ONCB leaves by one of two doors: nucleophilic displacement of the chlorine, or reduction of the nitro group — and most of the interesting downstream chemistry uses both, in sequence. The routes below are the general industrial pattern, not a process disclosure.
Start with the nitro-chloride
ONCB provides a chlorine activated toward displacement by the adjacent nitro group — an ortho pair of functional groups very few other cheap aromatics offer together.
Door one — displace the chlorine
Ammonia under pressure displaces chlorine to give 2-nitroaniline; alkoxides give ortho-nitroanisoles; other nucleophiles open further substitution routes.
Door two — reduce the nitro group
Catalytic hydrogenation or chemical reduction converts the nitro group to an amine, giving 2-chloroaniline directly, or ortho-phenylenediamine once the chlorine has already been displaced.
Finish to grade
The crude product is purified, crystallised or distilled, then standardised to whatever the end market demands — colour target, agro spec or pharmaceutical limit.
Why isomer purity carries through the whole route
Both doors are sensitive to what else is in the feed. Anything that competes for the reaction site, or carries its own reactivity, follows the material down the line:
- Para-isomer carryover reacts in parallel through the same chemistry, giving para-substituted contaminants that are difficult to strip once the ring has already been functionalised twice.
- Residual acidity from an incomplete wash can attack sensitive downstream intermediates and corrode process equipment over a campaign.
- Moisture is generally tolerable in the reduction step but interferes with anhydrous ammonolysis conditions and can affect reaction rate and yield.
- Colour bodies from oxidation or thermal stress dull the finished dye or pigment shade in colour-chemistry applications.
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 | Principal outlet |
|---|---|
| Ortho Nitro Chloro Benzene CAS 88-73-3 — this product | Ortho-phenylenediamine (OPDA) Benzimidazole fungicides Dyes & rubber chemicals |
| Para Nitro Chloro Benzene CAS 100-00-5 | Para-phenylenediamine Para-aminophenol Rubber antidegradants |
| 3,4-Dichloro Nitro Benzene CAS 99-54-7 | 3,4-Dichloroaniline Diuron, linuron, propanil |
If your route calls for a different nitrochlorobenzene or nitroaniline grade, we supply those as well — see our full product range. Send the CAS number and we will confirm the correct material before quoting.
What actually moves the price of this intermediate
ONCB 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.
Co-product economics
ONCB and its para isomer are always made together in the same nitration step. Demand for one isomer running ahead of the other changes the effective cost of both, since a producer cannot make more of one without making more of the other.
- Isomer ratio from the plant is roughly fixed
- An imbalanced demand cycle moves both prices
- We track this across our supplier panel
Upstream feedstock
The route back to ONCB runs through chlorobenzene and mixed-acid nitration. Movements in benzene, chlorine and nitric/sulfuric acid feed through to the nitrochlorobenzene within a quarter or so.
- Chlorine and benzene set the floor
- Acid and energy costs weigh on nitration economics
- We flag feedstock-driven moves in the quote
Regulatory pressure
An IARC 2B listing and acute-toxicity classification raise the compliance cost of producing, storing and moving this material. That cost sits inside the price, and it is one reason nitration capacity has consolidated in some regions.
- Handling obligations vary by jurisdiction
- Some markets restrict certain end uses
- We check destination rules before quoting
Pack format & phase
Molten (liquid) bulk movement is the cheapest way to move large volumes, but it needs heated storage and pumping at the receiving end. Drummed solid costs more per kilo but needs no special infrastructure.
- Molten bulk cuts cost at real volume
- Drums suit occasional or smaller buyers
- We help you choose based on your receiving setup
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 nitration 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 |
|---|---|
| OPDA / benzimidazole route | High assay with tight para-isomer limit |
| Dyes & pigments | Colour ceiling, tight isomer limit, low residue |
| Ammonolysis (2-nitroaniline) | Low moisture, controlled acidity |
| Pharmaceutical chain | Tight isomer limit; metals and residues reported |
| 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 the hazard profile. We state the acute-toxicity classification and IARC 2B listing 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 drummed store in a Gulf summer will keep the material molten, which is a different handling problem from a solid at a European site.
- Review your specification before it goes into a contract, so you are not locked into an isomer limit that no plant can consistently hit.
Regulatory & compliance notes
- IARC 2B obligations are jurisdiction-specific. Several regimes impose exposure monitoring, health surveillance and record retention for Group 2B substances. 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 this material. 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 colourant, agrochemical 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 drum
Send the specification
Product name or CAS 88-73-3, the assay and isomer limits you work to, quantity, pack preference (solid or molten) 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 nitrochlorobenzenes, anilines and diamines our agrochemical, rubber-chemical and dye customers most often order in the same programme. Each of the grades below is part of our wider range — visit the products page for current availability and specifications.
What buyers ask us about Ortho Nitro Chloro Benzene
Is this material classified as a carcinogen?
Can I use the para isomer instead?
What purity do you normally supply?
Will it arrive as a solid or a liquid?
What is the minimum order quantity?
How long does delivery take?
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 Ortho Nitro Chloro Benzene
Send your required assay, quantity, pack format (solid or molten) 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 drum or a contracted container programme for the year.