CAS 7790-94-5 · Chlorosulfonic Acid

Chlorosulfonic Acid: direct from source to Europe

Chlorosulfonic Acid (CAS 7790-94-5) is a fuming, corrosive liquid used as a powerful sulfonating and chlorosulfonating agent in the manufacture of dyes, pharmaceuticals, surfactants and sulfonamide intermediates.

  • COA, SDS & TDS with every batch
  • REACH status confirmed before quote
  • Samples available for qualification
Purityup to 99%+Assay, premium grade
Lead time3 – 6 weeksOrigin to European port
FormLiquid (fuming)Drums to ISO tank
Response1 business dayQuotation after receiving your spec
Product identification

Chlorosulfonic 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: Chlorosulfonic Acid, CAS 7790-94-5.

  • Confirmed CAS number on every COA
  • Premium grade with assay 99%+ available
  • TDS and SDS supplied with every shipment
Common name
Chlorosulfonic Acid
Synonyms
Chlorosulphonic acid · Sulfurochloridic acid · CSA
CAS number
7790-94-5
Formula / MW
ClSO3H  /  116.52 g/mol
Chemical family
Sulfonating and chlorosulfonating agent
HS code
2812 (halides and halide oxides of non-metals). Confirm the full code with your broker.

⚠ Reacts violently and exothermically with water, releasing HCl and SO₃/H₂SO₄ fumes. Always match CAS 7790-94-5 and handle strictly per the current SDS.

Technical data

Chlorosulfonic 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
Colourless to pale yellow fuming liquid
Pungent, acrid odour
Melting point
Approx. −80 °C
Typical value
Boiling point
Approx. 151–152 °C
Decomposes on heating
Molecular weight
116.52
g/mol
Molecular formula
ClSO3H
Sulfonating and chlorosulfonating agent
Solubility
Reacts violently with water
Hydrolyses to sulfuric acid and hydrogen chloride
Density
Approx. 1.75 g/cm³
At 20 °C
Storage
Sealed, dry, vented containers
Acid-resistant, moisture-excluded storage
Quality & specification

Chlorosulfonic 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 (ClSO₃H)
≥ 98.0%
≥ 99.0%
Titration
Sulfuric acid content
≤ 1.5%
≤ 0.5%
Titration
Residue on evaporation
≤ 0.10%
≤ 0.05%
Gravimetric
Colour
Colourless to pale yellow
Colourless to pale yellow
Visual check
Appearance
Clear, fuming liquid
Clear, fuming liquid
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 Chlorosulfonic Acid is used

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

Sulfonamide and dye synthesis

Direct sulfonyl chloride formation for sulfa drugs, dyes and pigments.

Surfactant intermediate

Feed for sulfonate-based surfactant chemistry.

Saccharin and specialty synthesis

Key reagent in saccharin and related heterocyclic sulfonamide routes.

Custom synthesis

Reagent for contract synthesis at industrial scale, for verified users only.

Packaging & logistics

Packed to your site, documented for customs

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

Drums

Lined steel drums

UN-approved acid-resistant lined steel drums with vented, sealed closures.

Up to 250 kg net
IBC

IBC / ISO tank

UN-approved acid-rated IBCs or ISO tank containers for higher-volume users.

On request
Bulk

Bulk supply

Bulk supply packed to agreement 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

Chlorosulfonic Acid: frequently asked questions

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

It is also sold as Chlorosulphonic acid, Sulfurochloridic acid, CSA. All refer to CAS 7790-94-5. 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.

Chlorosulfonic Acid (CAS 7790-94-5) is a fuming, corrosive liquid used as a powerful sulfonating and chlorosulfonating agent in the manufacture of dyes, pharmaceuticals, surfactants and sulfonamide intermediates.

Standard grade offers 98.0% minimum assay. Premium grade offers 99.0% minimum with lower sulfuric acid content and residue. Premium is recommended for pharmaceutical and fine-chemical sulfonation routes needing tight impurity control.

It reacts violently and exothermically with water and moisture, releasing corrosive hydrogen chloride and sulfuric acid/SO₃ fumes, and it is strongly corrosive to skin, eyes and metals. It must be handled under strictly anhydrous conditions with appropriate PPE, closed transfer systems and trained personnel, per the current SDS. We supply it only to verified industrial users.

Chlorosulfonic Acid is classified as corrosive and reacts dangerously with water, and can face REACH, CLP and transport obligations depending on use. We confirm the current status for your application before quoting.

Store in sealed, vented, acid-resistant containers under strictly dry conditions, away from water, organics, metals and combustible materials, in a dedicated, access-controlled area.

It is a corrosive dangerous good (Class 8, UN 1754; always confirm on the current SDS). We pack it in UN-approved, moisture-excluded 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 Chlorosulfonic 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