Para Nitrotoluene Ortho Sulphonic Acid
A sulfonated nitrotoluene intermediate supplied by Chelora Chemicals — made by sulfonating Para Nitrotoluene, and oxidatively coupled into the stilbene core of fluorescent brightening agents and dyes — exported from Indonesia with full batch documentation on every shipment.
What Para Nitrotoluene Ortho Sulphonic Acid is, and why buyers source it
A working overview of the compound's chemistry, how sulfonation sets up its stilbene-forming coupling chemistry, and the grades Chelora Chemicals keeps in regular supply.
Para Nitrotoluene Ortho Sulphonic Acid (PNT-OSA, also abbreviated PNTSA) is Para Nitrotoluene with a sulfonic acid group introduced at the ring position ortho to the methyl group (and meta to the nitro group). The combination of the nitro group, the sulfonic acid group and the methyl group on one ring gives a molecule set up for a specific and commercially important reaction: base-mediated oxidative self-condensation of the methyl groups of two molecules to form a central carbon-carbon double bond, building the stilbene core that underlies a major family of fluorescent whitening agents.
It is typically supplied as an off-white to light yellow solid, or as an aqueous slurry depending on the grade and how the buyer's downstream process intends to use it. It is water-soluble, consistent with its sulfonic acid functionality, and like other nitroaromatics is handled as a material requiring full MSDS-guided handling.
Where it fits in the synthesis chain
This compound's single most important downstream reaction is oxidative coupling under alkaline conditions (classically using sodium hypochlorite or a related oxidant) to form 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS), the precursor to a large family of optical/fluorescent brightening agents (FBAs) used in textiles, paper and detergents. It therefore sits at the entry point of one of the largest-volume downstream chains built on the nitrotoluene family.
Grades we supply
Chelora Chemicals offers Para Nitrotoluene Ortho Sulphonic Acid in standard technical grade (>95% assay, anhydrous basis) as either a dry powder or an aqueous slurry, to suit how your downstream process intends to use it. Each batch is supplied with a batch-wise certificate of analysis.
How Para Nitrotoluene Ortho Sulphonic Acid 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.
Para Nitrotoluene Ortho Sulphonic Acid is manufactured by sulfonating Para Nitrotoluene with concentrated or fuming sulfuric acid under controlled temperature. The methyl group directs the incoming sulfonic acid group predominantly to the ring position ortho to itself, which is also meta to the existing nitro group, giving this specific substitution pattern as the major product.
After sulfonation, the crude product is diluted, neutralised as required, and either isolated as a dry solid or retained as an aqueous slurry, depending on the grade and the buyer's intended downstream process, before packing.
Why this exact substitution pattern matters
The stilbene-brightener chemistry built on this molecule depends on having the nitro, methyl and sulfonic acid groups in precisely this relative arrangement; a different sulfonation position would not couple into the same useful dinitrostilbene-disulfonic acid product, which is why buyers specify this named isomer rather than a generic “nitrotoluenesulfonic acid.”
Industries and processes that use it
Para Nitrotoluene Ortho Sulphonic Acid is consumed almost entirely as the entry point to optical/fluorescent brightening agent manufacture. The fields below cover the uses we see through our export desk.
Optical Brightening Agent Manufacture
Oxidative coupling under alkaline conditions gives 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS), the precursor to a large family of fluorescent whitening agents used in textiles, paper and detergents.
Dye Intermediate Chemistry
Used more broadly as a sulfonated nitroaromatic building block in dye intermediate synthesis.
Specialty & Fine-Chemical Synthesis
Supplied as a well-characterised reference compound for specialty sulfonated nitroaromatic synthesis.
Regulatory & Analytical Reference Chemistry
Used as a reference standard in analytical methods for stilbene-brightener content and purity testing.
How the molecule is typically carried forward
The methyl group is the reactive handle for the stilbene-forming coupling reaction, while the nitro and sulfonic acid groups are generally carried through unchanged into the finished brightener. Reaction classes below cover the main ways this material is converted downstream.
Oxidative Coupling to Dinitrostilbene Disulfonic Acid
Under alkaline conditions with an oxidant such as sodium hypochlorite, two molecules couple at their methyl groups, forming a central carbon-carbon double bond and giving 4,4'-dinitrostilbene-2,2'-disulfonic acid — the single most important reaction this molecule undergoes.
Reduction of the Nitro Groups (Downstream)
Later in the brightener synthesis chain, the nitro groups on the coupled dinitrostilbene intermediate are reduced to amines as part of building the finished fluorescent brightening agent structure.
Further Derivatisation of the Sulfonic Acid
The sulfonic acid groups can be converted to other salts or derivatives as required by the specific brightener formulation being targeted.
Acid-Base Salt Formation
The sulfonic acid readily forms salts with various bases, a property exploited in formulation and purification steps throughout the brightener synthesis chain.
Para Nitrotoluene Ortho Sulphonic Acid against other nitrotoluene derivatives we supply
Buyers sourcing PNT-OSA are almost always in the optical brightener supply chain, and may also need its parent nitrotoluene. A quick reference to what else is on our regular supply list.
| Product | CAS Number | Category | Notes |
|---|---|---|---|
| Para Nitrotoluene Ortho Sulphonic Acid | 121-03-9 | Sulfonated nitrotoluene | The product on this page — the entry point to optical brightener manufacture. |
| Para Nitrotoluene | 99-99-0 | Mono-methyl mono-nitro aromatic | The starting material for this product — see its product page. |
| Ortho Nitrotoluene | 88-72-2 | Mono-methyl mono-nitro aromatic | A related nitrotoluene isomer — see its product page. |
| Meta Nitrotoluene | 99-08-1 | Mono-methyl mono-nitro aromatic | A related nitrotoluene isomer — 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, not a specification sheet, for products other than Para Nitrotoluene Ortho Sulphonic Acid.
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.
As a sulfonic acid, concentrated solutions can be corrosive to skin and eyes; treat splashes as an acid-exposure incident.
Treat as harmful if swallowed or inhaled, consistent with other nitroaromatic sulfonic acids.
Treat as potentially hazardous to the aquatic environment; avoid any release to drains or waterways.
Acid-resistant gloves, splash-proof eye protection and suitable respiratory protection are the baseline for routine handling.
Dry powder form can generate dust; local exhaust ventilation is recommended during transfer and weighing.
If supplied as an aqueous slurry, treat with the same acid-handling precautions as the dry form; confirm concentration before dosing.
Warning — confirm full classification against the SDS for the exact grade and form shipped.
As a nitroaromatic sulfonic acid, this compound should be handled as both an acid-corrosive and a nitroaromatic acute-toxicity hazard; acid-resistant gloves, splash-proof eye protection and suitable respiratory protection are the baseline for routine handling, with any skin or eye contact treated as an acid-exposure incident requiring immediate first aid. Full first-aid, storage, spill and PPE guidance is in the MSDS issued with every shipment, and should be read in full before this material is handled.
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 (for powder) or temperature-stable (for slurry) area away from direct sunlight, strong bases and strong oxidizing agents, in tightly closed original packaging. Slurry-grade material should be checked periodically for settling or crystallisation and re-mixed before dosing. If a batch is held past its retest date, re-check assay and colour before use.
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 Para Nitrotoluene Ortho Sulphonic Acid leaves with a documented, checkable paper trail.
Certificate of Analysis
Batch-wise assay (anhydrous basis), colour and residual starting material, 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 and form 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 Para Nitrotoluene Ortho Sulphonic Acid used for?+
02What is the CAS number of PNT-OSA?+
03How is PNT-OSA made?+
04What forms and grades does Chelora Chemicals supply?+
05Is PNT-OSA hazardous?+
06Why does this molecule matter for optical brighteners specifically?+
07What packing options are available?+
08How long does delivery take?+
09Can I get a sample before placing a bulk order?+
10Do you supply the parent nitrotoluene as well?+
Need Para Nitrotoluene Ortho Sulphonic Acid on spec, on time?
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