Ortho Chloro Para Nitro Aniline
A high-purity substituted nitroaniline supplied as an azo colour base for organic pigment and dye manufacture.
What is Ortho Chloro Para Nitro Aniline?
Ortho Chloro Para Nitro Aniline — OCPNA, or 2-chloro-4-nitroaniline — is a yellow crystalline powder carrying an amine with chlorine beside it and a nitro group across the ring.
It is one of a closely related pair of colour bases. Its isomer, 4-chloro-2-nitroaniline, carries the same three groups in swapped positions and the same molecular formula, but the two give visibly different shades and are ordered separately in pigment work.
At Chelora Chemicals, OCPNA is crystallised and refined with isomer content, melting range, and moisture held to specification, giving pigment manufacturers reproducible diazotisation and coupling between batches.
- Appearance
- Yellow crystalline powder
- Odour
- Faint amine odour
- Solubility
- Slightly soluble in water; soluble in alcohol, acetone, dilute acid
- Function
- Azo colour base / intermediate
- Grade
- Technical / dye
Formula diagram
Aniline with an ortho chlorine and a para nitro group
- Molecular formulaC6H5ClN2O2
- Molecular weight172.57 g/mol
- IUPAC name2-Chloro-4-nitroaniline
- Functional groupsPrimary aromatic amine, nitro, aryl chloride
- CAS number121-87-9
Technical product information
Standard specification for Chelora Chemicals' technical and dye grade Ortho Chloro Para Nitro Aniline. Custom-grade and bulk specifications are available on request.
| Chemical name | Ortho Chloro Para Nitro Aniline |
|---|---|
| Synonyms | OCPNA, 2-Chloro-4-nitroaniline, Fast Red 3GL Base variants |
| CAS number | 121-87-9 |
| Molecular formula | C6H5ClN2O2 |
| Molecular weight | 172.57 g/mol |
| Assay (purity) | ≥ 99.0% |
| Appearance | Yellow crystalline powder |
| Melting point | 107–109°C |
| Isomer content | ≤ 0.5% |
| Moisture | ≤ 0.5% |
| Residue on ignition | ≤ 0.2% |
| Packaging | 25 kg bags, 500 kg jumbo bags |
| Shelf life | 24 months from date of manufacture |
Applications of Ortho Chloro Para Nitro Aniline
Azo colour bases
Diazotised as a colour base for red and orange azo shades on textiles and leather.
Organic pigments
A diazo component in red and orange pigment manufacture for inks and coatings.
Dye intermediates
Feeds azo dye synthesis requiring a chloro-nitro substituted aniline.
Pharmaceutical intermediates
Used where a trifunctional aromatic core is needed in fine chemical synthesis.
Agrochemical intermediates
Applied in crop-protection routes built on substituted nitroaniline cores.
Analytical standards
Supplied as a reference material for aromatic amine testing.
Why choose Chelora Chemicals
Every batch of Ortho Chloro Para Nitro Aniline 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
Assay controlled at ≥99% with isomer content and melting range verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Flexible volumes
From 25 kg bags to 500 kg jumbo bags and full container loads.
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 away from heat, ignition sources, and direct sunlight.
- 03Segregate from strong oxidising agents, acids, and reducing agents.
- 04Keep bags palletised and dry; avoid dust generation and mechanical damage.
- 05Re-seal opened packaging promptly to prevent moisture pick-up and caking.
- 06Prevent release to drains, surface water, and soil.
Handling precautions
OCPNA is toxic by inhalation, ingestion, and skin absorption. It is for industrial use by trained personnel only.
Substituted nitroanilines are absorbed through intact skin and may affect the blood by forming methaemoglobin. Chemical-resistant gloves, coveralls, eye protection, and respiratory protection are required.
Control dust during bag emptying, sieving, and charging, and use local exhaust ventilation at all transfer points.
The product stains skin and surfaces strongly; treat any yellow discolouration of skin as evidence of contact and wash immediately.
Refer to the full Safety Data Sheet for exposure limits, spill response, and first-aid measures before use.
Frequently asked questions
What is Ortho Chloro Para Nitro Aniline used for?
It is an azo colour base, used mainly as a diazo component in red and orange pigment manufacture and in azoic dyeing. It also serves pharmaceutical and agrochemical intermediate synthesis.
How does it differ from 4-chloro-2-nitroaniline?
They are isomers. Both are C6H5ClN2O2 with a weight of 172.57 and carry the same three groups, but the chlorine and nitro positions are swapped. They melt at different temperatures and give visibly different shades, so they are ordered separately and are not interchangeable.
How do I make sure I order the right one?
Order against the CAS number. This product is 121-87-9; the isomer is 89-63-4. The written names are similar enough that transposition is a common source of error in pigment purchasing.
What does each substituent contribute to the colour?
The amine is the diazotisation site. The nitro group deepens the shade and improves lightfastness. The chlorine shifts the hue and improves wash and solvent fastness in the finished pigment.
Is it soluble in water?
Only slightly. It dissolves in alcohols, acetone, and dilute mineral acid, and acid dissolution is the normal first step before diazotisation.
Does it need a special diazotising agent?
Often, yes. Nitroanilines are weakly basic and can diazotise poorly in dilute aqueous acid, so nitrosyl sulfuric acid is commonly used instead of sodium nitrite for bases of this type.
What purity do you supply?
Standard grade is supplied at a minimum assay of 99% with isomer content at or below 0.5% and moisture at or below 0.5%. Tighter specifications can be produced to order.
What packaging sizes are available?
25 kg bags and 500 kg jumbo bags, with full container loads for bulk users. Samples are available for shade and coupling trials.
Are there regulatory restrictions on azo colourants?
Several jurisdictions restrict azo dyes that can release certain aromatic amines in consumer textiles and leather. Check whether your finished-article market imposes limits before committing to a route using this base.
Is OCPNA hazardous?
Yes. It is acutely toxic by several routes, absorbed through skin, and hazardous to aquatic life. Trained personnel, dust control, 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 assay, isomer content, melting range, moisture, and appearance.