Methyl trifluoromethanesulfonate

 ( Methylating Agents ) 

Methyl trifluoromethanesulfonate, also commonly called methyl triflate and abbreviated MeOTf, is the organic compound with the chemical formula . It is a colourless liquid which finds use in organic chemistry as a powerful Methylation agent.

The compound is closely related to methyl fluorosulfonate (). 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. Miscited as ——— (1976) Chem. Eng. News, vol. 54, no. 36, p. 56 in

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

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Reactivity

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

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Methylation One ranking of methylating agents is . Methyl triflate will alkylate many functional groups which are very poor nucleophiles such as , , and . It does not methylate benzene or the bulky 2,6-di- tert-butylpyridine. Its ability to methylate N-heterocycles is exploited in certain Protecting group schemes.

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Cationic polymerization

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

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

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Applications

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Radiochemistry

Carbon-11 methyl triflate (11CMeOTf), 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, 11CMeOTf has been used extensively in the production of Pittsburgh Compound B, which first allowed β-amyloid plaques to be imaged in a living brain.

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See also

• Triflate
• Magic methyl

Categories: Methylating Agents, Methyl Esters, Triflate Esters

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