Methyl fluorosulfonate

Methyl fluorosulfonate, also known as magic methyl, is the organic compound with the formula FSO₂OCH₃. It is a colorless liquid that is used as a strong methylating agent in organic synthesis. Because of its extreme toxicity, it has largely been replaced by the related reagent methyl trifluoromethanesulfonate.

Methyl fluorosulfonate

Names
Preferred IUPAC name Methyl sulfurofluoridate
Other names Methyl fluorosulphonate Fluorosulfonic acid, methyl ester Methyl fluorosulphate Magic methyl
Identifiers
CAS Number	421-20-5 Y
3D model (JSmol)	Interactive image
ChemSpider	9486 Y
ECHA InfoCard	100.006.369
PubChem CID	9870
UNII	N015VFJ94Z Y
CompTox Dashboard (EPA)	DTXSID8073180
InChI InChI=1S/CH3FO3S/c1-5-6(2,3)4/h1H3 Y Key: MBXNQZHITVCSLJ-UHFFFAOYSA-N Y InChI=1/CH3FO3S/c1-5-6(2,3)4/h1H3 Key: MBXNQZHITVCSLJ-UHFFFAOYAW
SMILES FS(=O)(=O)OC
Properties
Chemical formula	CH3FO3S
Molar mass	114.09 g·mol−1
Density	1.45 g/mL
Boiling point	93 °C (199 °F; 366 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Synthesis and reactions

It is prepared by distillation of an equimolar mixture of fluorosulfonic acid and dimethyl sulfate. It was originally produced by the reaction of methanol with fluorosulfonic acid.^[1]

Methyl fluorosulfonate is a highly electrophilic reagent for methylation. It is ranked as less powerful than methyl trifluoromethanesulfonate.^[2]

Toxicity

Toxicity of this reagent is equivalent to that of phosgene with an inhaled LC₅₀ (rat, 1 hour) of about 5 ppm. Several cases of poisoning resulting in death from pulmonary edema have been reported.^[3]