Ortho Nitro Chloro Benzene
A high-purity nitroaromatic intermediate supplied in flake and molten form for o-nitroaniline, o-anisidine, dye, pigment, and agrochemical synthesis.
What is Ortho Nitro Chloro Benzene?
Ortho Nitro Chloro Benzene — ONCB, or 1-chloro-2-nitrobenzene — is a yellow crystalline solid separated from the ortho/para mixture produced when chlorobenzene is nitrated. It melts just above 32°C, which is why it is frequently handled molten.
As with the para isomer, the nitro group activates the neighbouring chlorine toward nucleophilic aromatic substitution. Because that chlorine sits directly beside the nitro group, the products carry an ortho relationship between the two functional groups — the arrangement needed for benzimidazoles, o-phenylenediamine, and a range of heterocyclic intermediates.
At Chelora Chemicals, ONCB is refined with para-isomer content, melting range, and moisture held to specification, giving consistent conversion in amination, methoxylation, and reduction steps.
- Appearance
- Yellow crystalline flakes or molten liquid
- Odour
- Faint, sweetish aromatic
- Solubility
- Insoluble in water; soluble in alcohol, ether, benzene
- Function
- Chemical intermediate
- Grade
- Technical
Formula diagram
Chlorine and a nitro group on adjacent ring positions
- Molecular formulaC6H4ClNO2
- Molecular weight157.55 g/mol
- IUPAC name1-Chloro-2-nitrobenzene
- Functional groupsAryl chloride, nitro
- CAS number88-73-3
Technical product information
Standard specification for Chelora Chemicals' technical grade Ortho Nitro Chloro Benzene. Custom-grade and bulk specifications are available on request.
| Chemical name | Ortho Nitro Chloro Benzene |
|---|---|
| Synonyms | ONCB, 2-Nitrochlorobenzene, o-Chloronitrobenzene |
| CAS number | 88-73-3 |
| Molecular formula | C6H4ClNO2 |
| Molecular weight | 157.55 g/mol |
| Assay (purity) | ≥ 99.5% |
| Para isomer | ≤ 0.3% |
| Appearance | Yellow crystalline flakes or molten liquid |
| Melting point | 32–34°C |
| Boiling point | 246°C |
| Flash point | 127°C (closed cup) |
| Moisture | ≤ 0.1% |
| Packaging | 25 kg & 50 kg bags, 250 kg drums, molten tanker |
| Shelf life | 24 months from date of manufacture |
Applications of Ortho Nitro Chloro Benzene
o-Nitroaniline production
Aminated to o-nitroaniline, itself a major dye and heterocycle intermediate.
o-Anisidine & o-phenetidine
Methoxylated or ethoxylated to produce alkoxyaniline intermediates for dye chemistry.
Dyes & pigments
Feeds azo and sulfur dye routes as well as organic pigment intermediates.
Agrochemicals
Used in the synthesis of benzimidazole fungicides and other crop-protection actives.
Pharmaceutical intermediates
Provides an ortho-functionalised aromatic core for heterocyclic API building blocks.
Rubber & specialty chemicals
Applied in antioxidant, corrosion inhibitor, and specialty amine synthesis.
Why choose Chelora Chemicals
Every batch of Ortho Nitro Chloro 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
Ortho-isomer assay controlled at ≥99.5% with para content verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Flexible volumes
From 25 kg bags to drums and molten tanker supply.
Technical support
Process, handling, and compliance guidance from our chemistry team.
Storage and guidelines
- 01Store in tightly closed original packaging in a cool, dry, well-ventilated store.
- 02Keep below 25°C — the product melts near 32°C and will fuse in warm storage.
- 03Keep away from heat, sparks, open flame, and direct sunlight.
- 04Segregate from strong oxidising agents, strong bases, and reducing agents.
- 05Molten product requires dedicated heated lines, temperature control, and vapour extraction at charge points.
- 06Store in a locked or access-controlled area away from food, feed, and drinking water.
Handling precautions
ONCB is toxic by inhalation, ingestion, and skin absorption and is classified as a suspected carcinogen. It is for industrial use by trained personnel only.
Absorbed material can affect the blood by forming methaemoglobin. Chemical-resistant gloves, coveralls, eye protection, and respiratory protection are required for dust, vapour, and molten handling.
Molten product presents both a chemical and a thermal burn hazard. Use face protection and heat-resistant gloves during molten transfer and sampling.
Prevent release to drains, surface water, and soil; the product is hazardous to aquatic life.
Refer to the full Safety Data Sheet for exposure limits, medical surveillance, spill response, and first-aid measures before use.
Frequently asked questions
What is ONCB used for?
It is an intermediate. The chlorine is displaced by ammonia, methoxide, or other nucleophiles to give o-nitroaniline, o-anisidine, and related compounds, which then go into dyes, pigments, agrochemicals, and pharmaceutical building blocks.
What is the difference between ONCB and PNCB?
Both are C6H4ClNO2 with a molecular weight of 157.55, but ONCB has the nitro group next to the chlorine and PNCB has it opposite. ONCB melts near 33°C and PNCB near 83°C, and they lead to entirely different downstream products, so isomer purity is critical.
Why are the two isomers produced together?
Nitrating chlorobenzene gives a mixture in which the ortho and para products dominate. Plants separate them by crystallisation and distillation, and the isomer ratio and separation efficiency largely determine the economics of both products.
Can ONCB be supplied molten?
Yes, and many bulk users prefer it. Because the melting point is only about 33°C, molten supply in heated tankers avoids dust exposure and handling losses. The receiving site needs dedicated heated lines and temperature control.
Why does the flake fuse in the bag?
Warm-weather storage above roughly 30°C softens the material and causes flakes to cake or fuse. Keeping the store cool and out of direct sun prevents this; the assay is not affected.
Is ONCB soluble in water?
No. It is practically insoluble in water but dissolves readily in alcohols, ether, acetone, and aromatic solvents, so reactions are run in organic media or on the molten material.
What purity do you supply?
Standard technical grade is supplied at a minimum assay of 99.5% with para isomer at or below 0.3% and moisture at or below 0.1%. Tighter specifications can be produced to order.
What packaging sizes are available?
25 kg and 50 kg bags, 250 kg drums, and molten product in heated tankers. Samples are available for trial work.
Is ONCB hazardous?
Yes. It is classified as acutely toxic by several routes, harmful to the blood on repeated exposure, a suspected carcinogen, and hazardous to aquatic life. Trained personnel, engineering controls, and full PPE are required.
Do you provide a Certificate of Analysis?
Yes. Every batch ships with a Certificate of Analysis and Safety Data Sheet covering assay, isomer content, melting range, moisture, and appearance.