Ortho Nitroaniline
Ortho Nitroaniline is a yellow-orange crystalline intermediate used chiefly as the entry point to o-phenylenediamine, the building block behind the benzimidazole fungicide family — carbendazim and benomyl — and a range of azo pigments and sulfur dyes.
What Ortho Nitroaniline is, and why buyers source it
A working overview of the compound's chemistry, its place in the aniline-derivative family, and the grades Chelora Chemicals keeps in regular supply.
Ortho Nitroaniline (2-nitroaniline) is one of three positional isomers of nitroaniline, distinguished from its meta- and para- counterparts by having the nitro and amino groups adjacent on the ring. That adjacency is exactly what makes it useful: it sets up an intramolecular hydrogen bond between the two groups, which is part of why the ortho isomer melts lower (71–72°C) than the para isomer and behaves differently in downstream reduction chemistry.
Commercially, this compound is valued less for what it is and more for what it becomes. Catalytic or chemical reduction of the nitro group converts it to o-phenylenediamine (OPDA), a diamine that sits at the head of the benzimidazole family of compounds — most visibly the fungicides carbendazim and benomyl, both long-established agricultural actives. The same diamine chemistry also reaches into corrosion inhibitors and heterocyclic dye intermediates.
Where it fits in the synthesis chain
We supply this grade as the nitro precursor itself — we do not manufacture or supply o-phenylenediamine, carbendazim, or benomyl, and buyers sourcing this material for that downstream chain should confirm their own reduction and purification capability or route to a qualified toller.
Grades we supply
Technical grade (98% min) suits most pigment and chemical-intermediate uses; a tighter 99% min cut is offered where downstream reduction chemistry is sensitive to isomeric or dinitro contamination.
How Ortho Nitroaniline is made
An overview of the production route for orientation purposes. Our manufacturing partners' own process parameters and in-process controls are proprietary and are not disclosed beyond what is needed to interpret the certificate of analysis.
Ortho Nitroaniline is produced by nucleophilic aromatic substitution: ortho-nitrochlorobenzene (or ortho-nitrobromobenzene) is reacted with ammonia under pressure and heat, displacing the halogen and installing the amino group. This is the inverse order from most of the chloroaniline products in our range, where the amino group is already present and a reduction step follows — here, the nitro group is installed first (by nitrating chlorobenzene) and the amine is added second, directly, with no reduction step at this stage at all.
The reaction runs in aqueous or aqueous-alcoholic ammonia at elevated pressure, typically 150–180°C, in an autoclave. Excess ammonia drives the substitution and suppresses competing hydrolysis to the nitrophenol. After the reaction, the mixture is cooled, the product crystallises, and it is separated from unreacted ammonia and dissolved ammonium chloride by filtration and washing.
Crude product is purified by recrystallisation — commonly from aqueous ethanol — to remove residual ortho-nitrochlorobenzene, the para-isomer formed as a minor side-product during the upstream nitration-chlorination step, and inorganic salts. The isomer separation matters commercially: ortho- and para-nitroaniline have distinct melting points and reactivity downstream, and a blend that looks fine on a colour-and-assay certificate can still behave inconsistently in a customer's own reduction step if isomeric purity isn't controlled.
Why the halogen-displacement route, not nitration of aniline
A reasonable question is why this isn't simply made by nitrating aniline directly. In practice, nitrating aniline is not a clean route to this compound: the free amino group is a strong activator and the reaction is difficult to control, tends to over-oxidise, and gives poor isomer selectivity. Starting instead from pre-formed ortho-nitrochlorobenzene and displacing the chlorine with ammonia gives a cleaner, more controllable, and more isomerically selective synthesis — which is why this ammonolysis route, not direct nitration, is the standard industrial process.
Industries and processes that use it
Ortho Nitroaniline is consumed almost entirely as a synthesis intermediate. The four fields below account for most of the demand we see through our export desk.
o-Phenylenediamine Precursor
Catalytic or chemical reduction converts this to o-phenylenediamine, the entry point to the benzimidazole family of agrochemicals and heterocyclic intermediates.
Benzimidazole Fungicide Chain
Via o-phenylenediamine, this feeds the synthesis of carbendazim and benomyl, two long-established benzimidazole fungicides used in agriculture.
Azo Pigments & Dyes
Used as a diazotisable intermediate in select azo pigment and dye syntheses where the ortho-amino/nitro arrangement is specifically required.
Corrosion Inhibitor Intermediates
o-Phenylenediamine derivatives reached through this intermediate are used in some corrosion-inhibitor and heterocyclic-compound synthesis.
How the molecule is typically carried forward
The reaction chemistry of Ortho Nitroaniline centres on the nitro group, which is the reactive handle for every downstream use — reduced to an amine, retained as-is for its electron-withdrawing effect in further substitution, or occasionally used for diazotisation chemistry on the existing amino group.
Catalytic hydrogenation to o-phenylenediamine
Hydrogen over a palladium, platinum, or Raney nickel catalyst reduces the nitro group cleanly to an amine, giving o-phenylenediamine. This is the standard route to the benzimidazole-chain intermediate and is normally run by the downstream processor, not supplied by us as a finished reduction.
Chemical reduction (iron/HCl, sulfide, or catalytic transfer hydrogenation)
Where catalytic hydrogenation infrastructure isn't available, classical chemical reductants (iron filings with acid, sodium sulfide, or transfer hydrogenation agents) achieve the same nitro-to-amine conversion at smaller scale, at the cost of more aqueous waste to manage.
Diazotisation of the existing amino group
The amino group, not the nitro group, can be diazotised under standard cold nitrous-acid conditions to generate a diazonium salt for azo coupling — used in select pigment and dye syntheses that specifically need the ortho-nitro-substituted azo intermediate rather than the fully reduced diamine.
Ortho Nitroaniline against its near relatives
Ortho, meta, and para-nitroaniline are the three positional isomers of mononitroaniline, differing only in where the nitro group sits relative to the amine — but that single difference drives real differences in melting point, use, and the chemistry each one feeds into.
| Product | CAS Number | Typically Used In | Notes |
|---|---|---|---|
| Ortho Nitroaniline | 88-74-4 | o-Phenylenediamine → benzimidazole fungicides | The product on this page. mp 71–72°C. |
| Para Nitroaniline | 100-01-6 | p-Phenylenediamine → Para Red pigment chemistry | Also supplied — see its product page. mp 147–148°C. |
| 2,4-Dinitroaniline | 97-02-9 | Pigment Orange 5 intermediate | Also supplied — see its product page. mp 177–180°C. |
| Aniline | 62-53-3 | Parent amine for the entire product range | The unsubstituted parent compound — see its product page. |
Exact physical constants and purity specifications are confirmed per batch on the certificate of analysis — treat the notes above as a sourcing guide rather than a specification sheet.
Safety classification at a glance
Based on GHS classification as commonly listed for this substance. This is a summary for orientation only — always work from the current safety data sheet supplied with your specific batch.
Harmful if swallowed.
Harmful in contact with skin.
Harmful if inhaled.
Very toxic to aquatic life.
Very toxic to aquatic life with long lasting effects.
Warning
Ortho Nitroaniline carries no harmonised CMR classification under EU CLP Annex VI, and IARC has not evaluated this specific isomer. Its hazard profile is dominated by acute oral/dermal/inhalation toxicity and pronounced aquatic toxicity (H400/H410) rather than carcinogenicity — the aquatic hazard is the one we see suppliers understate most often, and it drives real handling requirements around spill containment and wastewater discharge. Supplier self-classifications under CLP Article 4(3) vary somewhat in which acute-toxicity category is assigned; our SDS reflects our own registered classification and should be checked against the version that ships with each shipment.
Keeping it on spec between delivery and use
General storage guidance for this grade. Site-specific storage rules, segregation requirements and re-test intervals should follow your own EHS procedures and the MSDS issued with your batch.
Store in a cool, dry, well-ventilated area away from oxidising agents, strong reducing agents, and direct sunlight, which can promote gradual darkening. Keep containers tightly sealed to prevent moisture pickup and caking of the crystalline product.
How it ships from Indonesia
Standard packing and export terms for this product. Confirm exact figures against your order — they vary slightly by destination and quantity.
What travels with every batch
Specification is agreed before the purchase order, not discovered on arrival. Every shipment of Ortho Nitroaniline leaves with a documented, checkable paper trail.
Certificate of Analysis
Batch-wise assay (by GC), isomer purity, melting point range and moisture, issued against the agreed specification so your QC team can check it, not just file it.
Safety Data Sheet
GHS-format SDS in English covering hazard classification, handling, storage, first-aid and spill response for the exact grade shipped.
Technical Data Sheet
Reference physical and chemical properties, recommended storage and typical applications, for internal circulation to your process or R&D teams.
Certificate of Origin
Confirms Indonesian origin for customs clearance and any preferential-duty claim at your destination port.
Dangerous Goods Declaration
UN packing group, classification and shipper's declaration prepared ahead of loading so documentation never holds up customs.
Third-Party Inspection
Independent pre-shipment inspection and re-sampling can be arranged on request, at your cost, for buyers who require it as a matter of policy.
Frequently asked questions
What buyers most often ask our sales desk about this grade.
01What is Ortho Nitroaniline used for?+
02What is the CAS number of Ortho Nitroaniline?+
03What purity grades does Chelora Chemicals supply?+
04Is Ortho Nitroaniline hazardous?+
05Do you supply o-phenylenediamine or carbendazim directly?+
06Is this the same as Meta or Para Nitroaniline?+
07Why does the aquatic toxicity hazard (H410) matter more here than for some of your other anilines?+
08What packing options are available?+
09How long does delivery take?+
10Can I get a sample before placing a bulk order?+
11How is Ortho Nitroaniline manufactured?+
12What is the shelf life, and how should it be stored?+
Need Ortho Nitroaniline on spec, on time?
Send us your required purity, quantity, packing preference and destination port. Our desk quotes most enquiries within one working day.