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Aliphatic and alicyclic building blocks

Methyl fluorosulfate

Also known as Methyl fluorosulfonate, Magic methyl, Methyl fluorosulphonate

CAS 421-20-5Formula CH3FO3SMolar mass 114.10 g/molEC 207-004-3
GHS signal word: Danger. Pictograms: Flammable, Corrosive, Acute toxicity (severe)
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Methyl fluorosulfate chemical structure, CH3FO3S, CAS 421-20-5
2D chemical structure

Key facts

What buyers check first

All properties
Physical form
Liquid
Boiling point
92 °C
Density
1.427 @ 16 °C
HS code
294200
Category
Aliphatic and alicyclic building blocks
Illustrative photo, 200 litre blue HDPE drums of liquid in a warehouse
Typical packagingIllustrative packaging image, not the actual product

What is Methyl fluorosulfate?

Plain description, key identifiers and synonyms

Methyl fluorosulfate is a chemical substance with the molecular formula CH3FO3S and a molar mass of 114.10 g/mol. Its CAS registry number is 421-20-5. The IUPAC name is fluorosulfonyloxymethane.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
fluorosulfonyloxymethane
CAS number
421-20-5 CAS number cross-checked
EC number
207-004-3
Molecular formula
CH3FO3S
UNII
N015VFJ94Z
MDL number
MFCD00014721
InChIKey
MBXNQZHITVCSLJ-UHFFFAOYSA-N
InChI
InChI=1S/CH3FO3S/c1-5-6(2,3)4/h1H3
SMILES (canonical and isomeric)
COS(=O)(=O)F

Synonyms

  • Methyl fluorosulfonate
  • Magic methyl
  • Methyl fluorosulphonate
  • fluorosulfonyloxymethane
  • methylfluorosulfonate
  • Methyl fluorosulphate
  • Methyl fluosulfonate
  • methyl sulfurofluoridate
  • Fluorosulfuric Acid Methyl Ester
  • Fluorosulfuric acid, methyl ester
  • Methyl Fluorosulfonate (stabilized with KF) [for Esterification]
  • Sulfuryl fluoride methyl ester
  • methyl fluoridosulfate
  • methyl sulfofluoridate
  • Fluorosulfonic Acid Methyl Ester
  • fluoridosulfuric acid (HSO_3_), methyl ester

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Physical form
Liquidexp.
Boiling point
92 °Cexp.
Density
1.427 @ 16 °Cexp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
114.10 g/molcalc.
Exact mass
113.9787 Dacalc.
LogP (octanol/water)
-0.15calc.
Topological polar surface area
43.37 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
3calc.
Rotatable bonds
1calc.
Heavy atoms
6calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
1calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS02: Flammable
Flammable
GHS05: Corrosive
Corrosive
GHS06: Acute toxicity (severe)
Acute toxicity (severe)

Hazard statements

  • H225Highly flammable liquid and vapour.
  • H301Toxic if swallowed.
  • H311Toxic in contact with skin.
  • H315Causes skin irritation.
  • H318Causes serious eye damage.
  • H330Fatal if inhaled.
Precautionary statements (32)
  • P210Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P233Keep container tightly closed.
  • P240Ground and bond container and receiving equipment.
  • P241Use explosion-proof electrical, ventilating and lighting equipment.
  • P242Use non-sparking tools.
  • P243Take action to prevent static discharges.
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P262Do not get in eyes, on skin, or on clothing.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P270Do not eat, drink or smoke when using this product.
  • P271Use only outdoors or in a well-ventilated area.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P284In case of inadequate ventilation wear respiratory protection.
  • P301 + P316If swallowed: Get emergency medical help immediately.
  • P302 + P352If on skin: Wash with plenty of water.
  • P303 + P361 + P353If on skin (or hair): Take off immediately all contaminated clothing. Rinse skin with water or shower.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316Get emergency medical help immediately.
  • P317Get medical help.
  • P320Specific treatment is urgent (see supplemental first aid instructions on the label).
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P330Rinse mouth.
  • P332 + P317If skin irritation occurs: Get medical help.
  • P361 + P364Take off immediately all contaminated clothing. And wash it before reuse.
  • P362 + P364Take off contaminated clothing. And wash it before reuse.
  • P370 + P378In case of fire: Use appropriate media to extinguish.
  • P403 + P233Store in a well-ventilated place. Keep container tightly closed.
  • P403 + P235Store in a well-ventilated place. Keep cool.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

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Methyl fluorosulfate price

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Uses and applications

What the substance is used for, by industry and function

Regulatory status

Inventories, regulations and trade controls that list this substance

No regulatory list memberships are recorded for this substance yet. Always check the rules of the importing and exporting country before trade.

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Methyl fluorosulfate is traded under.

HS 2942.00Indicative HS code

Organic compounds not elsewhere classified in chapter 29

World exports in 2024
$589M
−43.5% vs 2023, imports $614M
2019 to 2024
Top exporters
  1. India * partner reported20.7%
  2. United States18.6%
  3. Italy10.4%
Top importers
  1. United States15.1%
  2. Italy6.7%
  3. Japan5.3%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Methyl fluorosulfate is indicative (it is known at chapter level only). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Methyl fluorosulfate, based on the data on this page

What is Methyl fluorosulfate?

Methyl fluorosulfate is a chemical substance with the molecular formula CH3FO3S and a molar mass of 114.10 g/mol. Its CAS registry number is 421-20-5. The IUPAC name is fluorosulfonyloxymethane.

What is the CAS number of Methyl fluorosulfate?

The CAS registry number of Methyl fluorosulfate is 421-20-5.

What is the molecular formula and weight of Methyl fluorosulfate?

The molecular formula of Methyl fluorosulfate is CH3FO3S and its molar mass is 114.10 g/mol.

What is Methyl fluorosulfate used for?

Known uses and roles of Methyl fluorosulfate include building blocks in research and laboratory.

Is Methyl fluorosulfate hazardous?

Methyl fluorosulfate carries the GHS signal word "Danger". Main hazards: highly flammable liquid and vapour, toxic if swallowed, toxic in contact with skin. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Methyl fluorosulfate?

Methyl fluorosulfate is usually classified under HS code 294200 (XIII. OTHER ORGANIC COMPOUNDS, other organic compounds). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Methyl fluorosulfate?

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What is the price of Methyl fluorosulfate?

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Guides for buyers

Practical guides that help when you source, ship or handle Methyl fluorosulfate

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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