1-Hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, known in labs as [HMIM][NTf2] or HMIM TFSI, bridges pure science and practical innovation. With a formula of C10H19F6N3O4S2, this ionic liquid carves out space in applications ranging from advanced batteries to specialty solvents. The dual identity, with a hexyl-methylimidazolium cation and the robust bis(trifluoromethanesulfonyl)imide anion, sets up a unique molecular structure where organic meets highly fluorinated sulfonyls. This combination reveals itself through an oil-like viscosity, thermal stability, and low volatility. Experiencing its use means moving away from volatile organic compounds and toward safer, greener lab practices. The CAS number for reference is 174899-83-3, and its HS Code slots under 2933 (heterocyclic compounds with nitrogen hetero-atom only).
In practice, this chemical rarely limits itself to one appearance. Depending on how you buy it—straight from the manufacturer or custom-purified—it can show up as clear liquid, crystalline powder, or even pearlescent flakes. At room temperature, one often finds a colorless or pale yellow liquid. Its density hovers near 1.42 grams per cubic centimeter, a trait most can verify with a simple graduated cylinder and careful balance. Refractive index ranges around 1.420 to 1.435. Melting points can shift based on purity, but reports usually cluster in the -4 to -1°C range. This means a bottle left in a cold room often looks gel-like or semi-solid by morning. The ionic nature means extremely low vapor pressure and resistance to evaporation, which laboratory workers come to appreciate for safety and consistency.
HMIM TFSI stands apart because it resists hydrolysis and breakdown, even around strong acids or oxidizers. This quality means shelf life extends beyond many traditional solvents. It plays a role in electrolytes, catalysis, and separation processes, as it will not degrade into hazardous byproducts under typical experimental conditions. That said, contact with strong bases or at high temperatures—above 300°C—sets off decomposition and unpleasant fumes. From a safety perspective, eye and skin contact feels irritating, especially as microdroplets stick to gloves or benches, so a robust splash protocol matters. The trifluoromethanesulfonyl group drives its hydrophobicity, so water barely dissolves it, while polar organics like acetonitrile mix thoroughly. This enables the chemical to carry out phase transfers others can't.
Working with this material, the literature and personal experience both push for safe habits. Ingesting, inhaling, or getting this ionic liquid on your skin can irritate and cause more severe symptoms with high overexposure. Safety data sheets highlight it as harmful if swallowed, with potential for respiratory distress. The chemical does not ignite easily, but in a fire, the bis(trifluoromethanesulfonyl)imide group can release toxic gases, particularly fluorinated compounds that challenge standard ventilation. Gloves, goggles, and a fresh lab coat become essentials, and a dedicated chemical hood adds another layer of protection against inhalation.
From a waste management side, disposal should not happen down a drain. The persistence of fluorinated sulfonyl groups gives it environmental staying power, with aquatic impact still under research. Waste collection containers labeled for hazardous chemicals guarantee responsible end-of-life handling.
The design of this ionic liquid has fueled demand in cutting-edge research, especially in lithium ion and sodium ion batteries. Here, it serves as an electrolyte, offering a wide electrochemical window, flame resistance, and the ability to run at higher voltages. Research on supported catalysts finds this ionic liquid valuable as a stable solvent, while separation technologies embrace it for environmentally friendlier extractive operations. Synthesis of 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide starts with 1-hexylimidazole, methyl iodide, and lithium bis(trifluoromethanesulfonyl)imide as raw materials. Access to high-purity precursors impacts final yield and quality. These raw ingredients, when handled properly, make scalable production straightforward—even for research institutions pushing for ton-scale batches.
Large-scale storage prefers airtight, inert, and light-excluding containers. Over time, exposure to light can start to degrade the imidazolium ring, so maintenance of strict inventory protocols becomes routine for any high-volume user.
Labs and manufacturers exploring alternatives to volatile organic solvents find this imidazolium-based compound promising. Its low environmental emissions, high chemical stability, and non-flammable nature give it clear advantages. The rise of green chemistry, sustainable electronics, and regulations curbing VOCs turns this from a specialty product into a mainstream staple. Education makes a huge difference—training researchers and technicians ensures correct handling, from weighing to final disposal.
From a solutions perspective, investing in closed-loop recycling, improved PPE, and awareness of emergent regulations can cut risks and chemical costs. Encouraging broader data sharing on long-term health and environmental impacts of ionic liquids, including this one, will fill knowledge gaps. Manufacturers stepping up transparency on sourcing and purity will help end-users make informed decisions without unnecessary hazards or waste.
1-Hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide marks an important shift—from fossil-based solvents toward safer, more adaptable materials. Its molecular design, robust physical properties, and adaptability to a wide range of research and industrial settings move technology forward. Careful handling, ongoing research, and a commitment to best practices keep this innovation safe and sustainable.
