Methyl trifluoromethanesulfonate, also commonly called methyl triflate and abbreviated MeOTf, is the

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

. It is a colourless liquid which finds use in organic chemistry as a powerful methylating 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.

Synthesis

Methyl triflate is commercially available, however it may also be prepared in the laboratory by treating

dimethyl sulfate Dimethyl sulfate (DMS) is a chemical compound with formula (CH3O)2SO2. As the diester of methanol and sulfuric acid, its formula is often written as ( CH3)2 SO4 or Me2SO4, where CH3 or Me is methyl. Me2SO4 is mainly used as a methylating agen ...

with triflic acid. :

Reactivity

Hydrolysis

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

Methylation

One ranking of methylating agents is . Methyl triflate will alkylate many functional groups which are very poor nucleophiles such as

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula , where R, R', and R″ represent any group, typically organyl functional group, groups or hydrogen at ...

s, and

nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The name of the compound is composed of a base, which includes the carbon of the , suffixed with "nitrile", so for example is called " propionitrile" (or pr ...

s. It does not methylate benzene or the bulky 2,6-di-''tert''-butylpyridine. Its ability to methylate ''N''-heterocycles is exploited in certain

deprotection A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic synthesis. In man ...

schemes.

Cationic polymerization

Methyl triflate initiates the living cationic polymerization of

lactide Lactide is the lactone cyclic ester derived by multiple esterification between two (usually) or more molecules from lactic acid (2-hydroxypropionic acid) or other hydroxy carboxylic acid. They are designated as dilactides, trilactides, etc., acc ...

and other lactones including β-propiolactone, ε-caprolactone and

glycolide Glycolide (1,4-dioxane-2,5-dione) is a dimer of glycolic acid. Its structure is six-membered ring containing two lactones, an oxidized variant of ''p''-dioxane. The compound can be synthesized from glycolic acid, via a high-temperature oligomeri ...

Kationische_Polymerisation_von_Caprolacton_mit_Methyltriflat

Cyclic 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.

Applications

Radiochemistry

Carbon-11 methyl triflate ( 1CeOTf), or methyl triflate containing the carbon-11 isotope, is commonly used in

radiochemistry Radiochemistry is the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads t ...

to synthesize radioactively labeled compounds that can be traced in living organisms using

positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, r ...

(PET). For example, 1CeOTf 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

{{Reflist Methylating agents Methyl esters Triflate esters