Summary
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][better source needed]
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| Names | |
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| Preferred IUPAC name
Methyl trifluoromethanesulfonate | |
| Other names
Trifluoromethanesulfonic acid, methyl ester
Triflic acid, methyl ester, methyl triflate | |
| Identifiers | |
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3D model (JSmol)
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| ECHA InfoCard | 100.005.793 |
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PubChem CID
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| UNII |
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| UN number | 2924 |
CompTox Dashboard (EPA)
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| Properties | |
| 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) |
| Hydrolyzes | |
| Hazards[1] | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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Corrosive |
| GHS labelling: | |
| Danger | |
| H226, H301, H311, H314, H330 | |
| P210, P233, P303+P361+P353, P304+P340+P310, P305+P351+P338, P380 | |
| Flash point | 38 °C (100 °F; 311 K) |
| Related compounds | |
Related compounds
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Methyl fluorosulfonate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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Synthesis edit
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 edit
Hydrolysis edit
Upon contact with water, methyl triflate loses its methyl group, forming triflic acid and methanol:
- CF3SO2OCH3 + H2O → CF3SO2OH + CH3OH
Methylation edit
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 edit
Methyl triflate initiates the living cationic polymerization of lactide[5] and other lactones including β-propiolactone, ε-caprolactone and glycolide.[6]
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 edit
Radiochemistry edit
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.
See also edit
References edit
- ^ "Methyl trifluoromethanesulfonate". Sigma-Aldrich. Retrieved 31 October 2021.
- ^ a b c 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.
- ^ a b 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; Collected Volumes, 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.