1-Propyl-3-Methylimidazolium Tetrafluoroborate, better known in chemical circles as [BMIM][BF4], has become a go-to ionic liquid for folks working across electrochemistry, organic synthesis, and separation technologies. With a molecular formula of C7H15BF4N2 and a structure made up of a positively charged imidazolium cation linked to a tetrafluoroborate anion, this compound handles a set of applications where traditional solvents often fall short. In labs and industrial plants, people see it in different physical forms: sometimes as clear or faintly yellow liquid, sometimes as solid crystals, or even as a fine powder, pearls, or flakes, depending on temperature and specific composition.
This compound comes with a molecular weight of about 212.01 g/mol. It typically appears as a viscous liquid at room temperature, but it can present as crystals at lower temperatures or under certain storage conditions. Its density usually hovers around 1.24 g/cm³ at 25°C. That’s a notch heavier than water, so it has a grounded, substantial feel when handled. Solubility offers another practical advantage: it mixes well with a range of polar solvents, and, thanks to its ionic nature, doesn’t evaporate easily. That’s a significant property. The odds of it causing headaches through fumes are lower than with conventional volatile organic solvents. In reality, this means fewer environmental emissions and a safer workplace atmosphere, which matters to anyone who has spent time working with hazardous chemicals.
At its core, BMIM BF4 carries a bulky, aromatic imidazolium ring substituted with propyl and methyl groups, balanced by the [BF4]– anion. Chemists appreciate this arrangement—the cation forms strong ionic interactions, while the anion confers thermal and chemical stability. In electrochemical systems, it stands out for its broad electrochemical window and good ionic conductivity, pushing forward research in batteries and capacitors. I have seen researchers turn to this ionic liquid when more common materials failed either due to reactivity or breakdown at high voltages. Its high thermal stability also gives it an edge in catalytic and separation processes, as it resists degradation over broader temperature ranges.
One of the details that often comes up in procurement and safety reviews is the range of formats available. In supply, you find this compound packaged by the liter as a dense, clear liquid, but also in bulk as flakes, powder, pearls, or crystals. Storage and shipment require sealed containers—moisture and contamination run the risk of altering its properties. In the raw materials sector, purity ranks high, with specifications often demanding 99% or greater. This ensures maximum performance in technical applications. People working with large volumes—say, in pilot-scale syntheses or electrochemical screens—lean toward liquid or crystalline forms for ease of measurement and mixing.
BMIM BF4 does not carry the flammability risk of many traditional organic solvents, which, from years in the lab, always entered our risk assessments. But that doesn’t mean it comes off scot-free. Direct contact with skin or eyes can cause irritation, and gloves are standard protection. Some reports note mild toxicity upon ingestion or long-term exposure, especially in aquatic systems—this raises concern about safe disposal and spill control. In my experience, training often skips over proper ionic liquid waste procedures, but with BMIM BF4, collection and incineration through approved chemical disposal channels are critical. According to the Globally Harmonized System (GHS), this material holds a “Harmful” tag for aquatic environments, prompting companies to overhaul wastewater treatment protocols. The HS Code often aligns with 2933.29 for customs purposes, which streamlines international shipments but also flags it for specialized hazard inspections.
As demand rises, safety protocols deserve attention. Eye protection, nitrile gloves, and splash-resistant lab coats—these all cut incident rates. Ventilation, spill containment kits, and clear labeling reduce misuse and contamination. Recycling Ionic liquids is still in early stages; research teams are now evaluating re-refining and purification to make repeated use feasible, lowering environmental loads. Integrating these materials into closed-loop industrial systems also reduces leakage and disposal challenges. Looking at global supply chains, traceability and full documentation now come up more frequently as customers and regulators want to track where each liter came from, down to the batch and originating supplier. I have seen major labs in Europe and Asia start to implement these measures as pressure grows for transparency and accountability.
From electroplating and catalysis to advanced batteries and hydrogen storage, 1-Propyl-3-Methylimidazolium Tetrafluoroborate builds in flexibility. Researchers tap into its chemical stability and strong solvating power to extract metals, support transition-metal catalysts, and boost reaction selectivity in green chemistry projects. Pharmaceutical companies experiment with it for drug synthesis. People pushing into energy storage use its broad electrochemical window to build safer and higher performing devices. This growth opens questions about sourcing raw materials responsibly and managing waste. Suppliers with an eye for sustainability are now publishing safety data and life-cycle assessments, responding to customer requests and regulatory requirements. In the end, those in the lab and on the factory line both look for reliability—and, increasingly, for responsible stewardship of every kilogram or liter bought, used, and eventually, disposed.
