Formula CF3SO3CH3 Boiling point 100 °C Appearance Colourless Liquid | Molar mass 164.1 g/mol Density 1.5 g/cm³ | |
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Methyl trifluoromethanesulfonate, also commonly called methyl triflate (abbreviated MeOTf), is the organic compound with the formula CF3SO2OCH3. It is a colourless liquid which finds use in organic chemistry as a very powerful (and very dangerous) methylating agent.
Contents
Synthesis
Methyl triflate is commercially available, however it may also be prepared in the laboratory via a number of routes. For instance: the reaction of methanol with trifluoromethanesulfonic anhydride in the presence of pyridine. In this approach the methyl triflate may be removed from the triflic acid by-product by fractional distillation. Alternatively, triflic acid can be methylated by high temperature reactions with other alkylating agents, such as methyl iodide or dimethyl carbonate.
Reactivity
The compound hydrolyzes violently upon contact with water:
CF3SO2OCH3 + H2O → CF3SO2OH + CH3OHThis compound is closely related to methyl fluorosulfonate (FSO2OCH3), which is an older reagent, now less commonly used. These compounds alkylate faster and with wider range of substrates than traditional methylating agents such as methyl iodide. One ranking of alkylating agents is (CH3)3O+ > CF3SO2OCH3 ≈ FSO2OCH3 > (CH3)2SO4 > CH3I. It will alkylate many functional groups that are only weakly basic such as aldehydes, amides, and nitriles. It does not methylate benzene or the bulky 2,6-di-tert-butylpyridine. Its ability to methylate N-heterocycles is exploited in certain deprotection schemes.