Ortho Nitro Aniline
A high-purity nitroaniline supplied as orange-yellow crystals for azo dye and pigment manufacture, o-phenylenediamine production, and heterocyclic synthesis.
What is Ortho Nitro Aniline?
Ortho Nitro Aniline — ONA, or 2-nitroaniline — is an orange-yellow crystalline solid in which an amino group and a nitro group occupy adjacent positions on a benzene ring. It is produced by aminating ortho nitrochlorobenzene.
That ortho arrangement is the whole point of the molecule. The two groups can be closed into a five-membered heterocycle, or the nitro group can be reduced to give o-phenylenediamine, the direct precursor to benzimidazole chemistry used in fungicides and pharmaceuticals.
At Chelora Chemicals, ONA is crystallised and refined with assay, melting range, and moisture held to specification, giving dye and pigment manufacturers a diazo component with consistent shade and coupling behaviour.
- Appearance
- Orange-yellow crystalline powder
- Odour
- Faint amine odour
- Solubility
- Slightly soluble in water; soluble in alcohol, ether, hot acid
- Function
- Chemical intermediate
- Grade
- Technical / dye
Formula diagram
Amino and nitro groups on adjacent ring positions
- Molecular formulaC6H6N2O2
- Molecular weight138.13 g/mol
- IUPAC name2-Nitroaniline
- Functional groupsPrimary aromatic amine, nitro
- CAS number88-74-4
Technical product information
Standard specification for Chelora Chemicals' technical grade Ortho Nitro Aniline. Custom-grade and bulk specifications are available on request.
| Chemical name | Ortho Nitro Aniline |
|---|---|
| Synonyms | ONA, 2-Nitroaniline, o-Nitroaniline, Fast Orange Base GR |
| CAS number | 88-74-4 |
| Molecular formula | C6H6N2O2 |
| Molecular weight | 138.13 g/mol |
| Assay (purity) | ≥ 99.0% |
| Appearance | Orange-yellow crystalline powder |
| Melting point | 71–73°C |
| Boiling point | 284°C |
| Flash point | > 150°C (closed cup) |
| Isomer content | ≤ 0.5% |
| Moisture | ≤ 0.5% |
| Packaging | 25 kg bags, 500 kg jumbo bags |
| Shelf life | 24 months from date of manufacture |
Applications of Ortho Nitro Aniline
Azo dye intermediates
Diazotised as a colour base for azo dyes across textile and leather applications.
Organic pigments
Used as a diazo component in orange and red pigment manufacture for inks and coatings.
o-Phenylenediamine route
Reduced to o-phenylenediamine, the precursor to benzimidazole chemistry.
Agrochemical intermediates
Feeds benzimidazole fungicide synthesis and related crop-protection routes.
Pharmaceutical intermediates
Provides an ortho-difunctional aromatic core for heterocyclic API building blocks.
Specialty chemicals
Applied in corrosion inhibitors, photographic chemicals, and analytical reagents.
Why choose Chelora Chemicals
Every batch of Ortho 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 mechanical damage and dust generation.
- 05Re-seal opened packaging promptly to prevent moisture pick-up and caking.
- 06Prevent release to drains, surface water, and soil.
Handling precautions
ONA is toxic by inhalation, ingestion, and skin absorption. It is for industrial use by trained personnel only.
Nitroanilines can be 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 Nitro Aniline used for?
It is a dye and pigment intermediate, used as a diazo component for azo colours, and a precursor to o-phenylenediamine for benzimidazole fungicides and pharmaceutical intermediates.
How is ONA manufactured?
Commercially by ammonolysis of ortho nitrochlorobenzene, in which ammonia displaces the chlorine that is activated by the neighbouring nitro group. Isomer purity of the ONCB feed carries through to the finished amine.
Why does the ortho arrangement matter?
Having the amino and nitro groups on adjacent carbons means both can participate in forming a fused five-membered ring. That is the direct route into benzimidazoles, which is not available from the meta or para isomers.
What is the difference between ONA, MNA, and PNA?
They are the ortho, meta, and para isomers of nitroaniline, sharing the formula C6H6N2O2. They differ in melting point, colour, and coupling behaviour, and they are not interchangeable in dye or heterocycle synthesis.
Is it soluble in water?
Only slightly. It dissolves in alcohols, ether, and hot dilute acids. For diazotisation it is normally dissolved in mineral acid before treatment with sodium nitrite.
Why is the product orange rather than white?
The colour comes from the electronic interaction between the electron-donating amino group and the electron-withdrawing nitro group across the ring. The intense colour is intrinsic and is not an indication of impurity.
What purity do you supply?
Standard technical 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 manufactured 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.
How should ONA be stored?
In sealed original packaging in a cool, dry, ventilated store away from oxidising agents and acids, palletised and protected from moisture. Shelf life is 24 months from manufacture.
Is ONA hazardous?
Yes. It is classified as acutely toxic by several routes, harmful on repeated exposure, and hazardous to aquatic life. Handling requires trained personnel, dust control, and full PPE 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.