Methyl trifluoromethanesulfonate

Methyl trifluoromethanesulfonate
Names
	Preferred IUPAC name Methyl trifluoromethanesulfonate
	Other names Trifluoromethanesulfonic acid, methyl ester; Triflic acid, methyl ester, methyl triflate
Identifiers
CAS Number	333-27-7 ;
3D model (JSmol)	Interactive image;
ChemSpider	9153 ;
ECHA InfoCard	100.005.793
EC Number	206-371-7;
PubChem CID	9526;
UNII	7B25Z22EPV ;
UN number	2924
CompTox Dashboard (EPA)	DTXSID6049272 ;
	InChI InChI=1S/C2H3F3O3S/c1-8-9(6,7)2(3,4)5/h1H3 Key: OIRDBPQYVWXNSJ-UHFFFAOYSA-N ; InChI=1/C2H3F3O3S/c1-8-9(6,7)2(3,4)5/h1H3 Key: OIRDBPQYVWXNSJ-UHFFFAOYAL;
	SMILES COS(=O)(=O)C(F)(F)F;
Properties
Chemical formula	C2H3F3O3S
Molar mass	164.10 g·mol−1
Appearance	Colourless Liquid
Density	1.496 g/mL
Melting point	−64 °C (−83 °F; 209 K)
Boiling point	100 °C (212 °F; 373 K)
Solubility in water	Hydrolyzes
Hazards[1]
	Occupational safety and health (OHS/OSH):
Main hazards	Corrosive
	GHS labelling:
Signal word	Danger
Hazard statements	H226, H301, H311, H314, H330
Precautionary statements	P210, P233, P303+P361+P353, P304+P340+P310, P305+P351+P338, P380
Flash point	38 °C (100 °F; 311 K)
Related compounds
Related compounds	Methyl fluorosulfonate
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Methyl trifluoromethanesulfonate, also commonly called methyl triflate and abbreviated MeOTf, is the organic compound with the formula CF₃SO₂OCH₃. It is a colourless liquid which finds use in organic chemistry as a powerful methylating agent.[2] The compound is closely related to methyl fluorosulfonate (FSO₂OCH₃). Although there has yet to be a reported human fatality, several cases were reported for methyl fluorosulfonate (LC₅₀ (rat, 1 h) = 5 ppm), and methyl triflate is expected to have similar toxicity based on available evidence.[2]

Synthesis

Methyl triflate is commercially available, however it may also be prepared in the laboratory by treating dimethyl sulfate with triflic acid.[3]

CF₃SO₂OH + (CH₃O)₂SO₂ → CF₃SO₂OCH₃ + CH₃OSO₂OH

Reactivity

Hydrolysis

Upon contact with water, methyl triflate loses its methyl group, forming triflic acid and methanol:

CF₃SO₂OCH₃ + H₂O → CF₃SO₂OH + CH₃OH

Methylation

One ranking of methylating agents is (CH₃)₃O⁺ > CF₃SO₂OCH₃ ≈ FSO₂OCH₃ > (CH₃)₂SO₄ > CH₃I.[3] Methyl triflate will alkylate many functional groups which are very poor nucleophiles such as aldehydes, amides, and nitriles. It does not methylate benzene or the bulky 2,6-di-tert-butylpyridine.[2] Its ability to methylate N-heterocycles is exploited in certain deprotection schemes.[4]

Cationic polymerization

Methyl triflate initiates the living cationic polymerization of lactide[5] and other lactones including β-propiolactone, ε-caprolactone and glycolide.[6]

Polymerization of ε-caprolactone initiated by methyl triflate

Cyclic carbonates like trimethylene carbonate and neopentylene carbonate (5,5-dimethyl-1,3-dioxan-2-one) can be polymerized to the corresponding polycarbonates.[7] 2-alkyl-2-oxazolines, for example 2-ethyl-2-oxazoline, are also polymerized to poly(2-alkyloxazoline)s.[8]

Applications

Radiochemistry

Carbon-11 methyl triflate ([11C]MeOTf[9]), or methyl triflate containing the carbon-11 isotope, is commonly used in radiochemistry to synthesize radioactively labeled compounds that can be traced in living organisms using positron emission tomography (PET). For example, [11C]MeOTf has been used extensively in the production of Pittsburgh Compound B, which first allowed β-amyloid plaques to be imaged in a living brain.

References

"Methyl trifluoromethanesulfonate". Sigma-Aldrich. Retrieved 31 October 2021.
Roger W. Alder; Justin G. E. Phillips; Lijun Huang; Xuefei Huang (2005). "Methyltrifluoromethanesulfonate". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rm266m.pub2. ISBN 0471936235.
Stang, Peter J.; Hanack, Michael; Subramanian, L. R. (1982). "Perfluoroalkanesulfonic Esters: Methods of Preparation and Applications in Organic Chemistry". Synthesis. 1982 (2): 85–126. doi:10.1055/s-1982-29711. ISSN 0039-7881.
Albert I. Meyers & Mark E. Flanagan (1998). "2,2′-Dimethoxy-6-formylbiphenyl". Organic Syntheses.; Collective Volume, vol. 9, p. 258
Rangel, Irma; Ricard, Michèle; Ricard, Alain (1994). "Polymerization of L-lactide and ε-caprolactone in the presence of methyl trifluoromethanesulfonate". Macromolecular Chemistry and Physics. 195 (9): 3095–3101. doi:10.1002/macp.1994.021950908.
Jonté, J. Michael; Dunsing, Ruth; Kricheldorf, Hans R. (1985). "Polylactones. 4. Cationic Polymerization of Lactones by Means of Alkylsulfonates". Journal of Macromolecular Science: Part A - Chemistry. 22 (4): 495–514. doi:10.1080/00222338508056616. ISSN 0022-233X.
Kricheldorf, Hans R.; Weegen-Schulz, Bettina; Jenssen, Jörg (1998). "Cationic polymerization of aliphatic cyclocarbonates". Macromolecular Symposia. 132 (1): 421–430. doi:10.1002/masy.19981320139.
Glassner, Mathias; D’hooge, Dagmar R.; Young Park, Jin; Van Steenberge, Paul H.M.; Monnery, Bryn D.; Reyniers, Marie-Françoise; Hoogenboom, Richard (2015). "Systematic investigation of alkyl sulfonate initiators for the cationic ring-opening polymerization of 2-oxazolines revealing optimal combinations of monomers and initiators". European Polymer Journal. 65: 298–304. doi:10.1016/j.eurpolymj.2015.01.019. hdl:1854/LU-5924229.
Jewett, D. M. (1992). "A simple synthesis of [11C]methyl triflate". International Journal of Radiation Applications and Instrumentation, Part A. 43 (11): 1383–1385. doi:10.1016/0883-2889(92)90012-4. hdl:2027.42/29777. ISSN 0883-2889. PMID 1333459.

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[1] "Methyl trifluoromethanesulfonate". Sigma-Aldrich. Retrieved 31 October 2021.

[eEROS-2] Roger W. Alder; Justin G. E. Phillips; Lijun Huang; Xuefei Huang (2005). "Methyltrifluoromethanesulfonate". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rm266m.pub2. ISBN 0471936235.

[Stang-3] Stang, Peter J.; Hanack, Michael; Subramanian, L. R. (1982). "Perfluoroalkanesulfonic Esters: Methods of Preparation and Applications in Organic Chemistry". Synthesis. 1982 (2): 85–126. doi:10.1055/s-1982-29711. ISSN 0039-7881.

[4] Albert I. Meyers & Mark E. Flanagan (1998). "2,2′-Dimethoxy-6-formylbiphenyl". Organic Syntheses.; Collective Volume, vol. 9, p. 258

[5] Rangel, Irma; Ricard, Michèle; Ricard, Alain (1994). "Polymerization of L-lactide and ε-caprolactone in the presence of methyl trifluoromethanesulfonate". Macromolecular Chemistry and Physics. 195 (9): 3095–3101. doi:10.1002/macp.1994.021950908.

[6] Jonté, J. Michael; Dunsing, Ruth; Kricheldorf, Hans R. (1985). "Polylactones. 4. Cationic Polymerization of Lactones by Means of Alkylsulfonates". Journal of Macromolecular Science: Part A - Chemistry. 22 (4): 495–514. doi:10.1080/00222338508056616. ISSN 0022-233X.

[7] Kricheldorf, Hans R.; Weegen-Schulz, Bettina; Jenssen, Jörg (1998). "Cationic polymerization of aliphatic cyclocarbonates". Macromolecular Symposia. 132 (1): 421–430. doi:10.1002/masy.19981320139.

[8] Glassner, Mathias; D’hooge, Dagmar R.; Young Park, Jin; Van Steenberge, Paul H.M.; Monnery, Bryn D.; Reyniers, Marie-Françoise; Hoogenboom, Richard (2015). "Systematic investigation of alkyl sulfonate initiators for the cationic ring-opening polymerization of 2-oxazolines revealing optimal combinations of monomers and initiators". European Polymer Journal. 65: 298–304. doi:10.1016/j.eurpolymj.2015.01.019. hdl:1854/LU-5924229.

[9] Jewett, D. M. (1992). "A simple synthesis of [11C]methyl triflate". International Journal of Radiation Applications and Instrumentation, Part A. 43 (11): 1383–1385. doi:10.1016/0883-2889(92)90012-4. hdl:2027.42/29777. ISSN 0883-2889. PMID 1333459.