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In
organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J ...
, triflate ( systematic name: trifluoromethanesulfonate), is a
functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the r ...
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 ...
and
structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such a ...
. The triflate group is often represented by , as opposed to −Tf, which is the triflyl group, . For example, ''n''-butyl triflate can be written as . The corresponding triflate
anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
, , is an extremely stable
polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zero. The term molecule may or may no ...
; this comes from the fact that triflic acid () is a
superacid In chemistry, a superacid (according to the classical definition) is an acid with an acidity greater than that of 100% pure sulfuric acid (), which has a Hammett acidity function (''H''0) of −12. According to the modern definition, a superaci ...
; i.e. it is more acidic than pure
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
, already one of the strongest
acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...
s known.


Applications

A triflate group is an excellent leaving group used in certain
organic reactions Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemi ...
such as nucleophilic substitution,
Suzuki coupling The Suzuki reaction is an organic reaction, classified as a cross-coupling reaction, where the coupling partners are a boronic acid and an organohalide and the catalyst is a palladium(0) complex. It was first published in 1979 by Akira Suzuki, ...
s and
Heck reaction The Heck reaction (also called the Mizoroki–Heck reaction) is the chemical reaction of an unsaturated halide (or triflate) with an alkene in the presence of a base and a palladium catalyst (or palladium nanomaterial-based catalyst) to form a s ...
s. Since alkyl triflates are extremely reactive in SN2 reactions, they must be stored in conditions free of
nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they ar ...
s (such as
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
). The anion owes its stability to resonance stabilization which causes the negative charge to be spread symmetrically over the three oxygen atoms. An additional stabilization is achieved by the trifluoromethyl group, which acts as a strong electron-withdrawing group using the sulfur atom as a bridge. Triflates have also been applied as ligands for group 11 and 13 metals along with
lanthanide The lanthanide () or lanthanoid () series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yt ...
s.
Lithium triflate Lithium triflate (lithium triflouromethanesulfonate or LiOTf) is a salt with the chemical formula LiCF3SO3. It is composed of the lithium cation (Li+) and triflate anion (CF3SO3−; TfO−). It is very hygroscopic. The salt is used in lithium-ion ...
s are used in some lithium ion batteries as a component of the
electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon ...
. A mild triflating reagent is phenyl triflimide or ''N'',''N''-bis(trifluoromethanesulfonyl)aniline, where the by-product is F3SO2N−Phsup>−.


Triflate salts

Triflate
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
s are thermally very stable with melting points up to 350 °C for
sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...
,
boron Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the '' boron group'' it has t ...
and
silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
salts especially in water-free form. They can be obtained directly from triflic acid and the metal hydroxide or metal carbonate in water. Alternatively, they can be obtained from reacting metal chlorides with neat triflic acid or
silver triflate Silver trifluoromethanesulfonate, or silver triflate is the triflate (CF3SO3−) salt of Ag+. It is a white or colorless solid that is soluble in water and some organic solvents including, benzene. It is a reagent used in the synthesis of organi ...
, or from reacting barium triflate with metal sulfates in water: :MCl_\mathit + \mathit HOTf -> M(OTf)_\mathit + \mathit HCl :MCl_\mathit + \mathit AgOTf -> M(OTf)_\mathit + \mathit AgCl (v) :M(SO4)_\mathit + \mathit Ba(OTf)2 -> M(OTf)_ + \mathit BaSO4 v Metal triflates are used as
Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
catalysts in
organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J ...
. Especially useful are the lanthanide triflates of the type (where Ln is a lanthanoid). A related popular catalyst scandium triflate is used in such reactions as
aldol reaction The aldol reaction is a means of forming carbon–carbon bonds in organic chemistry. Discovered independently by the Russian chemist Alexander Borodin in 1869 and by the French chemist Charles-Adolphe Wurtz in 1872, the reaction combines two ...
s and
Diels–Alder reaction In organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a peric ...
s. An example is the
Mukaiyama aldol addition The Mukaiyama aldol addition is an organic reaction and a type of aldol reaction between a silyl enol ether and an aldehyde or formate. The reaction was discovered by Teruaki Mukaiyama (1927–2018) in 1973. His choice of reactants allows ...
reaction between
benzaldehyde Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor. ...
and the silyl enol ether of
cyclohexanone Cyclohexanone is the organic compound with the formula (CH2)5CO. The molecule consists of six-carbon cyclic molecule with a ketone functional group. This colorless oily liquid has an odor reminiscent of acetone. Over time, samples of cyclohex ...
with an 81%
chemical yield In chemistry, yield, also referred to as reaction yield, is a measure of the quantity of moles of a product formed in relation to the reactant consumed, obtained in a chemical reaction, usually expressed as a percentage. Yield is one of the pr ...
. The corresponding reaction with the
yttrium Yttrium is a chemical element with the symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a " rare-earth element". Yttrium is almost always found in co ...
salt fails: Triflate is a commonly used weakly coordinating anion.


See also

*
Methyl triflate 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. T ...
* Nonaflate *
Trifluoromethanesulfonic acid Triflic acid, the short name for trifluoromethanesulfonic acid, TFMS, TFSA, HOTf or TfOH, is a sulfonic acid with the chemical formula CF3SO3H. It is one of the strongest known acids. Triflic acid is mainly used in research as a catalyst for es ...
*
Metal triflimidate A metal triflimidate M(NTf2)''n'' in organic chemistry is a metal salt or complex of triflimidic acid and used as a catalyst. Metal triflimidates are prepared by reaction of metal oxides, carbonates, hydroxides, or halides with triflimidic acid in ...
*
Comins' reagent The Comins' reagent is a triflyl-donating reagent that is used to synthesize vinyl triflates from the corresponding ketone enolates or dienolates. It was first reported in 1992 by Daniel Comins. The vinyl triflates prepared are useful as su ...
*
Lithium Triflate Lithium triflate (lithium triflouromethanesulfonate or LiOTf) is a salt with the chemical formula LiCF3SO3. It is composed of the lithium cation (Li+) and triflate anion (CF3SO3−; TfO−). It is very hygroscopic. The salt is used in lithium-ion ...


References

{{reflist Sulfonic acids Leaving groups Anions Trifluoromethyl compounds