chemistry

Bistriflimide

Bistriflimide is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Bistriflimide rather than just read about it. In short: Bistriflimide, also known variously as bis(trifluoromethane)sulfonimide, bis(trifluoromethanesulfonyl)imide, bis(trifluoromethanesulfonyl)imidate (and variations thereof), informally and somewhat inaccurately as triflimide or triflimidate, or by the abbreviations TFSI or NTf2, is a non-coordinating anion with the chemical formula [(CF3SO2)2N]−. Its salts are typically referred to as being metal triflimidates.

Key takeaways

Bistriflimide belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Bistriflimide to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Bistriflimide from memory before moving on to harder problems.

Reference excerpt

Bistriflimide, also known variously as bis(trifluoromethane)sulfonimide, bis(trifluoromethanesulfonyl)imide, bis(trifluoromethanesulfonyl)imidate (and variations thereof), informally and somewhat inaccurately as triflimide or triflimidate, or by the abbreviations TFSI or NTf2, is a non-coordinating anion with the chemical formula [(CF3SO2)2N]−. Its salts are typically referred to as being metal triflimidates.

Applications The anion is widely used in ionic liquids (such as trioctylmethylammonium bis(trifluoromethylsulfonyl)imide), since it is less toxic and more stable than more "traditional" counterions such as tetrafluoroborate. This anion is also of importance in lithium-ion and lithium metal batteries (LiTFSI) because of its high dissociation and conductivity. It has the added advantage of suppressing crystallinity in poly(ethylene oxide), which increases the conductivity of that polymer below its melting point at 50 °C.

Bistriflimidic acid

The conjugate acid of bistriflimide, which is frequently referred to by the trivial name bistriflimidic acid (sometimes shortened to triflimidic acid; CAS: 82113-65-3), is a commercially available superacid. It is a crystalline compound, but is hygroscopic to the point of being deliquescent. Owing to its very high acidity and good compatibility with organic solvents it has been employed as a catalyst in a wide range of chemical reactions. Its pKa value in water cannot be accurately determined but in acetonitrile it has been estimated as −0.10 and in 1,2-dichloroethane −12.3 (relative to the pKa value of 2,4,6-trinitrophenol (picric acid), anchored to zero to crudely approximate the aqueous pKa scale), making it more acidic than triflic acid (pKaMeCN = 0.70, pKaDCE(relative to picric acid) = −11.4).

Naming Developing an IUPAC name for bistriflimide that indicates the structure and reactivity is challenging, and changes to current names have been proposed. The main difficulty arises from the ambiguous use of the word amide to mean an acylated (including sulfonylated) amine or the anionic form of an amine. Likewise, imide can refer to a bisacylated amine or a twice deprotonated amine. Thus, depending on the system used, there is ambiguity as to whether amide or imide is being used to refer to the parent acid or the anion. (The anion has been referred to as an amidate or imidate in an attempt to distinguish it from the acid.) The complications in naming these compounds was highlighted in an article by the IUPAC. Since then, the IUPAC has recommended (2013) that derivatives of anionic nitrogen can be named as azanides, so bis(trifluoromethanesulfonyl)azanide would be an acceptable and unambiguous name for the bistriflimide anion. The parent acid, whose trivial name is bistriflimidic acid, would then be called bis(trifluoromethanesulfonyl)azane. The name 1,1,1-trifluoro-N-((trifluoromethyl)sulfonyl)methanesulfonamide is also an unambiguous IUPAC-acceptable name, though the symmetry of the molecule is not apparent from this construction.

See also Triflic acid Triflidic acid Comins' reagent

References

Illustrations

Worked examples

Example 1 — a first encounter with Bistriflimide

Start with the simplest possible case. Write down what Bistriflimide claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Bistriflimide before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Bistriflimide ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Bistriflimide

In research: Bistriflimide appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Bistriflimide in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Bistriflimide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Non-coordinating anions, Organic compounds with 2 carbon atoms, Sulfonamides, so understanding it makes those chapters shorter.
In everyday life: Look for Bistriflimide outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Bistriflimide in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Bistriflimide means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Bistriflimide out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Bistriflimide in simple terms?

Why does Bistriflimide matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Bistriflimide?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Bistriflimide.