CAS 121-03-9 · Para Nitrotoluene Ortho Sulphonic Acid

Para Nitrotoluene Ortho Sulphonic Acid: direct from source to Europe

Para Nitrotoluene Ortho Sulphonic Acid (CAS 121-03-9), known in the trade as PNTOSA, is a sulfonated nitrotoluene used as an intermediate for azo dyes, optical brighteners and specialty sulfonated aromatics.

  • COA, SDS & TDS with every batch
  • REACH status confirmed before quote
  • Samples available for qualification
Purityup to 98%+HPLC assay, premium grade
Lead time3 – 6 weeksOrigin to European port
FormSolid25 kg bags to bulk
Response1 business dayQuotation after receiving your spec
Product identification

Para Nitrotoluene Ortho Sulphonic Acid: names, synonyms and identifiers

Buyers search for this material under several names. Whichever one appears on your specification, purchase order or REACH dossier, it is the same compound: Para Nitrotoluene Ortho Sulphonic Acid, CAS 121-03-9.

  • Confirmed CAS number on every COA
  • Premium grade with assay 98%+ available
  • TDS and SDS supplied with every shipment
Common name
Para Nitrotoluene Ortho Sulphonic Acid
Synonyms
PNTOSA · 4-Nitrotoluene-2-sulfonic acid · 4-Methyl-3-nitrobenzenesulfonic acid
CAS number
121-03-9
Formula / MW
C7H7NO5S  /  217.20 g/mol
Chemical family
Nitrotoluene sulfonic acid
HS code
2904 (halogenated, sulfonated, nitrated or nitrosated derivatives of hydrocarbons). Confirm the full code with your broker.

⚠ PNTOSA is an industry trade name for 4-nitrotoluene-2-sulfonic acid; it is supplied as the free acid or, on request, as the sodium salt. Always match CAS 121-03-9.

Technical data

Para Nitrotoluene Ortho Sulphonic Acid physical and chemical properties

Key parameters for process engineering, safety planning and storage design. Values are typical; always verify against the current TDS for your lot.

Appearance
Off-white to light yellow crystalline powder
Hygroscopic
Melting point
Decomposes above 100 °C
No sharp melting point
Boiling point
Not applicable
Decomposes before boiling
Molecular weight
217.20
g/mol
Molecular formula
C7H7NO5S
Nitrotoluene sulfonic acid
Solubility
Soluble in water
Also soluble in polar organic solvents
Physical form
Solid
Free acid or sodium salt on request
Storage
Cool & dry
Sealed, away from moisture
Quality & specification

Para Nitrotoluene Ortho Sulphonic Acid grade specifications: standard vs premium

Two grades are offered so your process chemist or quality team can pick what suits downstream requirements. COA parameters are confirmed before every shipment.

Parameter
Standard grade
Premium grade
Test method / note
Assay (HPLC)
≥ 96.0%
≥ 98.0%
HPLC area %
Water content
≤ 3.0%
≤ 1.0%
Karl Fischer titration
Sulfate ash
≤ 1.0%
≤ 0.5%
Gravimetric
Identity
Confirmed
Confirmed
HPLC or IR
Appearance
Off-white to light yellow crystalline powder
Off-white to light yellow crystalline powder
Visual check

All values are specification limits, not guaranteed minima. Actual COA figures for your lot are provided before dispatch. Non-standard specifications are available on enquiry.

Applications

Where Para Nitrotoluene Ortho Sulphonic Acid is used

Typical end uses and synthesis routes for European manufacturers, toll processors and laboratories.

Azo dye intermediate

Diazo component for water-soluble azo dyes.

Optical brightener intermediate

Sulfonated building block for stilbene-type brighteners.

Specialty sulfonated aromatics

Feed for further reduction to amino-sulfonic acid derivatives.

Custom synthesis

Starting material for contract synthesis of nitrotoluene sulfonic acid derivatives.

Packaging & logistics

Packed to your site, documented for customs

Para Nitrotoluene Ortho Sulphonic Acid is handled as a dangerous good. Every shipment leaves with UN-approved packaging, CLP labelling and the full document set for European import.

Bags

25 kg bags

UN-approved bags or lined fibre packs on pallets, suitable for FCL and LCL.

25 kg net
Drums

200 kg drums

UN-approved steel or fibre drums for higher volume users.

200 kg net
Bulk

Jumbo bags / bulk

Bulk bags for high-volume users, supplied on request for suitable receiving sites.

On request
Document set included: Bill of lading · Commercial invoice · Packing list · Certificate of analysis (COA) · Safety data sheet (SDS) · Dangerous goods declaration (IMDG/ADR) · Certificate of origin · Other certificates on request
Common questions

Para Nitrotoluene Ortho Sulphonic Acid: frequently asked questions

Quick answers for European buyers. For anything else, email source@cheloragroup.com.

It is also sold as PNTOSA, 4-Nitrotoluene-2-sulfonic acid, 4-Methyl-3-nitrobenzenesulfonic acid. All refer to CAS 121-03-9. Confirm the CAS number with any supplier before ordering.

Price depends on grade, volume, packing, Incoterm and destination port, and moves with raw material markets. Send us your requirement and we will quote in EUR or USD with a landed-cost breakdown, usually within one business day.

Para Nitrotoluene Ortho Sulphonic Acid (CAS 121-03-9), known in the trade as PNTOSA, is a sulfonated nitrotoluene used as an intermediate for azo dyes, optical brighteners and specialty sulfonated aromatics.

Standard grade offers 96.0% minimum HPLC assay. Premium grade offers 98.0% minimum with lower water content and ash. Premium is recommended for optical brightener routes needing tight impurity control.

We supply Para Nitrotoluene Ortho Sulphonic Acid primarily as the free acid. The sodium salt can be supplied on request; tell us which form your process needs, and confirm you mean CAS 121-03-9 rather than a related nitrotoluene sulfonic acid isomer.

Aromatic amines can face REACH, CLP and workplace-exposure obligations depending on use. We confirm the current status for your application before quoting.

Store sealed in a cool, dry place, away from moisture, strong bases and reducing agents. Use within the shelf life stated on the COA and TDS.

It is treated as a dangerous good (class and UN number per SDS; always confirm on the current SDS). We pack it in UN-approved containers, apply CLP labels and ship through licensed forwarders under IMDG for sea and ADR for European road.

Yes. Laboratory and pilot samples are supplied with a COA and SDS so your team can qualify the grade. Mention sample needs in your enquiry.

REACH status is confirmed before we quote. We advise on importer-of-record arrangements and whether the substance is registered for your use. Send your use descriptor and we will confirm.

Ready to source?

Get your Para Nitrotoluene Ortho Sulphonic Acid quotation today

Send us the grade, volume, destination and Incoterm. You will receive a clear price, packaging options and a full document checklist, usually within one business day.

  • Samples to full containers
  • COA, SDS and DG documents included as standard
  • Quote in EUR or USD, your choice of Incoterm