CAS 8014-95-7 · Oleum 23%

Oleum 23%: direct from source to Europe

Oleum 23% (CAS 8014-95-7) is a fuming solution of sulfur trioxide in sulfuric acid, nominally 23% free SO₃, used for sulfonation, nitration mixed-acid systems and other strongly dehydrating and sulfonating processes.

  • COA, SDS & TDS with every batch
  • REACH status confirmed before quote
  • Samples available for qualification
Purity23% ±0.5%Free SO₃ content, standard grade
Lead time3 – 6 weeksOrigin to European port
FormLiquid (fuming)ISO tank / bulk
Response1 business dayQuotation after receiving your spec
Product identification

Oleum 23%: 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: Oleum 23%, CAS 8014-95-7.

  • Confirmed CAS number on every COA
  • Premium grade with free SO₃ 23% ±0.3% available
  • TDS and SDS supplied with every shipment
Common name
Oleum 23%
Synonyms
Fuming sulfuric acid 23% · Oleum (20–24% SO₃) · Disulfuric acid solution
CAS number
8014-95-7
Formula / MW
H2SO4 + SO3  /  Mixture g/mol
Chemical family
Fuming sulfuric acid (oleum)
HS code
2807 (sulphuric acid; oleum). Confirm the full code with your broker.

⚠ Always state the free SO₃ strength (nominally 23%) together with CAS 8014-95-7 when ordering; oleum strengths are not interchangeable without recalculating your process.

Technical data

Oleum 23% 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
Fuming, colourless to pale straw liquid
Fumes strongly in moist air
Freezing point
Approx. 5–10 °C
Varies with exact SO₃ content
Boiling point
Decomposes on heating
Releases SO₃ fumes
Free SO₃ content
23% nominal
By weight
Composition
H2SO4 + free SO3
Fuming sulfuric acid
Solubility
Reacts violently with water
Always add oleum to water, never the reverse, and only under controlled conditions
Density
Approx. 1.87 g/cm³
At 20 °C
Storage
Sealed, dry, vented tanks
Acid-resistant, moisture-excluded storage
Quality & specification

Oleum 23% 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
Free SO₃ content
22.5–23.5%
22.8–23.2%
Titration
Iron (Fe)
≤ 50 ppm
≤ 15 ppm
Colorimetric or ICP
Residue on ignition
≤ 0.05%
≤ 0.02%
Gravimetric
Colour
Colourless to pale straw
Colourless to pale straw
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 Oleum 23% is used

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

Sulfonation

Aromatic sulfonation for dyes, surfactants and pharma intermediates.

Mixed-acid nitration

Component of nitrating mixtures for nitroaromatic synthesis.

Dehydration reactions

Strong dehydrating agent in specialty organic synthesis.

Battery and specialty acid blending

Feed for adjusting sulfuric acid concentration and specialty acid grades.

Packaging & logistics

Packed to your site, documented for customs

Oleum 23% is handled as a dangerous good. Every shipment leaves with UN-approved packaging, CLP labelling and the full document set for European import.

Drums

Drums & carboys

UN-approved acid-resistant drums and carboys on pallets, suitable for FCL and LCL.

25–250 kg net
IBC

IBC totes

UN-approved acid-rated IBCs for medium-volume users.

1,000–1,500 kg
Bulk

ISO tank / bulk

ISO tank containers or bulk supply for suitable receiving sites.

20–25 t
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

Oleum 23%: frequently asked questions

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

It is also sold as Fuming sulfuric acid 23%, Oleum (20–24% SO₃), Disulfuric acid solution. All refer to CAS 8014-95-7. 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.

Oleum 23% (CAS 8014-95-7) is a fuming solution of sulfur trioxide in sulfuric acid, nominally 23% free SO₃, used for sulfonation, nitration mixed-acid systems and other strongly dehydrating and sulfonating processes.

Standard grade holds free SO₃ at 22.5–23.5%. Premium grade holds a tighter 22.8–23.2% band with lower iron and residue. Premium is recommended for sulfonation processes needing precise, reproducible stoichiometry.

Both are fuming sulfuric acid, but they differ in free SO₃ content: 23% versus 65% by weight. The higher-strength grade delivers more SO₃ per tonne shipped and is used for more demanding sulfonation or where less sulfuric acid dilution is wanted. The two are not interchangeable without recalculating your stoichiometry; confirm which strength your process needs.

Oleum is corrosive and reactive, and is a reportable substance under the EU explosives precursors rules (Regulation (EU) 2019/1148) as fuming sulfuric acid, in addition to REACH obligations. We confirm the current status for your application before quoting.

Store in sealed, vented, acid-resistant tanks under dry conditions, away from water, organics, metals and combustible materials. Oleum reacts violently with water and releases SO₃ fumes on exposure to moist air.

It is a corrosive dangerous good (Class 8, UN 1831, fuming sulfuric acid; always confirm on the current SDS). We pack it in UN-approved tanks or 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 Oleum 23% 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