- Zinc triflate, also known as zinc trifluoromethanesulfonate or zinc trifluoromethanesulfonate dihydrate, is an inorganic compound with the formula Zn(OTf)₂, where OTf stands for the trifluoromethanesulfonate anion (CF₃SO₃⁻), commonly called triflate. It is usually encountered as a white to off-white crystalline powder and is highly soluble in water and polar organic solvents such as acetonitrile, methanol, and dimethylformamide (DMF). The compound is often used in its hydrated form and is considered air-stable under normal laboratory conditions.
- Zinc triflate is primarily valued for its role as a Lewis acid catalyst in organic synthesis. The triflate anion is a non-coordinating, weakly basic counterion, which allows the zinc cation (Zn²⁺) to remain highly electrophilic and available for interaction with reactants. This makes zinc triflate particularly effective in promoting a wide range of reactions, such as Friedel–Crafts acylations and alkylations, Diels–Alder reactions, Michael additions, acetalizations, and transesterifications. It is also used to activate carbonyl compounds and to catalyze the formation of carbon-carbon and carbon-heteroatom bonds under mild conditions.
- In polymer chemistry, zinc triflate has been explored as a catalyst for ring-opening polymerization, especially for producing polyesters and polycarbonates. Its solubility and reactivity in both aqueous and non-aqueous media make it useful for homogeneous catalysis and facilitate its recovery and reuse. Compared to traditional Lewis acids like aluminum chloride or ferric chloride, zinc triflate is often preferred because of its higher moisture tolerance, lower corrosivity, and easier handling, making it attractive for environmentally conscious synthesis protocols.
- In coordination chemistry and materials science, zinc triflate serves as a precursor for synthesizing zinc-organic frameworks and zinc-containing complexes. The combination of a strongly Lewis acidic center with weakly coordinating anions also makes it useful in developing ionic liquids and electrolytes for electrochemical devices, such as batteries or capacitors.
- Despite its usefulness, zinc triflate should be handled with care. It can cause skin and eye irritation, and like other metal triflates, it may release toxic or corrosive byproducts (e.g., triflic acid) if exposed to strong acids or elevated temperatures. It should be stored in a cool, dry environment in tightly sealed containers, preferably under inert atmosphere for moisture-sensitive applications.
- Overall, zinc triflate is a highly versatile reagent and catalyst, combining the reactivity of zinc with the beneficial properties of the triflate anion. It plays an important role in modern organic synthesis, catalysis, and materials development, particularly where strong Lewis acidity and non-nucleophilic counterions are desired.
