N-Butylimidazolium Bis((Trifluoromethyl)Sulfonyl)Imide, commonly referred to under the abbreviation [Bmim][NTf2], stands as an ionic liquid composed of an N-butylimidazolium cation and a bis((trifluoromethyl)sulfonyl)imide anion. This material falls into the family of room-temperature ionic liquids, notable for their non-volatile and non-flammable nature. Its chemical formula is C11H20F6N3O4S2, and the CAS number most often cited is 174899-82-2. In daily lab work, this compound introduces new possibilities for electrochemistry, solvents in synthesis, and advanced energy storage systems, serving as an example of how molecular design impacts real-world innovation.
Looking at its physical characteristics, N-Butylimidazolium Bis((Trifluoromethyl)Sulfonyl)Imide comes in several forms. It often appears as a colorless to pale yellow liquid, though solid crystals or snow-like flakes may be observed at lower temperatures due to its melting point, which sits around 2°C to 4°C. In the lab, I have handled it both in thick, syrupy solutions and as glassy, transparent solid forms. Its density stands close to 1.43 g/cm³ at room temperature. On contact, it does not carry the pungency or irritation commonly associated with strong acids or volatile solvents, which makes it relatively friendly for measured handling, but gloves and protection should still be worn since ionic liquids occasionally penetrate skin or trigger sensitivity reactions. The substance’s molecular weight is about 422.42 g/mol.
One property that often draws chemists to [Bmim][NTf2] is its remarkable thermal and chemical stability. It withstands temperatures exceeding 300°C before decomposing, supporting applications where regular organic solvents would break down. Its hydrophobic character – it doesn’t mix well with water – opens up creative uses in biphasic reaction systems. The bis(trifluoromethyl) group lends strong electron-withdrawing ability, further boosting its resistance to oxidation and hydrolysis. The viscosity of this ionic liquid sits higher than typical organic solvents, which affects how easily it mixes and flows; this feature sometimes benefits processes that require retention of reactants or precise control over reaction speed.
The structure of N-Butylimidazolium Bis((Trifluoromethyl)Sulfonyl)Imide blends a planar imidazolium ring with a straight butyl side chain, combining flexibility and directional polarity. The anion’s large, delocalized electron cloud—derived from sulfonyl and trifluoromethyl groups—disperses charge efficiently, which explains why this compound shows such low vapor pressure and forms stable ionic matrices even when exposed to heat. The crystalline arrangement seen under microscopy often reflects stacked arrangements, with cations and anions alternating in a loose, yet ordered pattern. From my work, this unique structure cooperates with both organic and metallic species, making the compound a versatile partner in catalysis and industrial synthesis.
High-purity [Bmim][NTf2] grades are supplied for use in advanced material synthesis, lithium battery research, and high-precision chemical transformations. Specifications frequently mention purity above 99%, water content below 0.2%, appearance as clear to pale yellow liquid or colorless crystals, and strict limits for halide or organic impurity residues. The compound is packed in sealed glass or high-density polyethylene bottles for bulk purchase. I always check for dry ice packs in shipping because even a small amount of moisture can shift its conductivity and impurity profile.
Even though [Bmim][NTf2] does not burn or explode under usual lab conditions, safety remains key. Direct exposure can irritate skin or eyes, so standard protocol includes nitrile gloves, goggles, and long sleeves. Its relatively low toxicity doesn’t mean outright safety; some studies suggest ionic liquids accumulate in the environment, impacting aquatic life if disposed improperly. Waste should not go down the drain or ordinary trash—dedicated solvent recovery or chemical waste streams are required. As for storage, sealed dark bottles at ambient temperatures keep it stable for months, minimizing risks of hydrolysis or decomposition.
N-Butylimidazolium Bis((Trifluoromethyl)Sulfonyl)Imide arrives to customers in a diverse set of physical forms. Large commercial suppliers offer options including viscous liquid, crystalline flakes, fine white powder, glassy solid wafers, and uniform pearls. This variety depends greatly on temperature and humidity control during shipping and storage. In energy device labs, I have received both bottle and ampule formats, chosen to preserve purity from air and moisture intrusion. Scaling up, raw materials used for production center on 1-butylimidazole, chlorinated intermediates, bis(trifluoromethylsulfonyl)imide, and solvents like acetonitrile—each tightly controlled to avoid contamination.
The mixture’s density, hydrophobic nature, and resistance to chemical breakdown position it as desirable for solvent-free extractions, electrochemical devices, and advanced polymer structuring. In my direct work with lithium battery materials, blends incorporating [Bmim][NTf2] provided not just safer alternatives to volatile carbonate electrolytes, but opened doors for flexible device formats and longer cycle lives. In many organic transformations, chemists replace toxic or noxious solvents like dichloromethane or toluene with this ionic liquid, cutting emission hazards and lowering environmental impact.
Shipments of N-Butylimidazolium Bis((Trifluoromethyl)Sulfonyl)Imide typically assign Harmonized System (HS) code 2933.39 for customs processing, classifying it among heterocyclic compounds with nitrogen hetero-atom(s) only. While regulatory frameworks still evolve for ionic liquids, importers and users must pay attention to regional restrictions, labeling, Safety Data Sheet (SDS) requirements, and safe transport protocols. The unique status of ionic liquids—being neither conventional solvents nor hazardous waste—sometimes delays clear classification, prompting ongoing updates from international agencies.
Concerns around [Bmim][NTf2] stem from the persistence and possible accumulation of fluorinated moieties in ecosystems. Research teams publish continual updates on its low volatility, minimizing air emission, but some ionic liquids do build up in aquatic environments, impacting algae and small invertebrates. My own laboratory approach stresses containment, solvent recovery, and waste minimization to curb these effects. An outright hazard to users remains low if handled with basic chemical hygiene, but regulatory agencies continue to review whether lingering raw materials or improper disposal might contribute to long-term environmental stress.
To address sustainability and safety, production facilities and buyers should implement strict containment and waste treatment systems. Closed-cycle recovery, distillation of spent liquids, and rigorous water treatment protocols help limit leaching or accidental discharge. Researchers developing next-generation ionic liquids can focus on finding more biodegradable variants, swapping perfluoroalkyl groups for less persistent options. On my end, I consistently favor remote work-up and in-lab capture using activated carbon beds or selective absorbents, cutting down the risk that [Bmim][NTf2] leaves the lab environment or industrial setting. Education and best-practice sharing among chemists, engineers, and procurement specialists strengthen the safe and impactful use of this flexible chemical across its growing array of applications.
