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 (LC
50 (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 ...
s, 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 ...
.
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.
See also
* Triflate
In organic chemistry, triflate (Preferred IUPAC name, systematic name: trifluoromethanesulfonate), is a functional group with the Chemical formula, formula and Chemical structure, structure . The triflate group is often represented by , as opp ...
* Magic methyl
References
{{Reflist
Methylating agents
Methyl esters
Triflate esters