Properties and Applications of 1-Butyl-3-methylimidazolium Hexafluorophosphate

1-Butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆, CAS number: 174501-64-5) is a representative imidazolium-based ionic liquid, characterized by its exceptional chemical stability, low volatility, and favorable solubility and extraction capabilities. At room temperature, it presents as a light yellow, transparent, and viscous liquid. Its molecular formula is C₈H₁₅N₂F₆P,with a molecular weight of 284.18 g/mol, a density of approximately 1.38 g/mL, a melting point of 6.5°C, and a boiling point exceeding 340°C. This ionic liquid is miscible with organic solvents like methanol, chloroform, and ethyl acetate, while remaining insoluble in water.

Purity: ≥97%

Packaging: 25g 100g 1kg 25kg

Transport conditions: Regular transport

Ionic liquids play a pivotal role in advancing environmentally benign chemical reactions, with 1-butyl-3-methylimidazolium hexafluorophosphate being a prime example utilized across a spectrum of green chemistry applications. Beyond its general utility, this ionic liquid acts as a reaction medium for specialized transformations such as the ring-closing metathesis of diene and enyne substrates using a recyclable ruthenium carbene complex, the nickel(II) acetylacetonate-catalyzed oxidation of aromatic aldehydes to acids with hydrogen peroxide, the lipase-mediated enantioselective acylation of allyl alcohols, and the allylation of aldehydes with tetraallylstannane to yield homoallylic alcohols.

Synthesis Method

It is primarily synthesized through the reaction of N-methylimidazole with butyl bromide, resulting in the formation of 1-butyl-3-methylimidazole chloride ([C4mim]Cl). Subsequently, this chloride salt undergoes ion exchange with either sodium hexafluorophosphate (Na[PF6]) or potassium hexafluorophosphate. Typically, the reaction is conducted in an ice-water bath to maintain low temperatures. Following the reaction, the product is dissolved in dichloromethane, thoroughly washed with water to remove impurities, subjected to distillation under reduced pressure to purify it further, and finally dried under vacuum conditions.

Optimizing the synthesis process represents a significant area of research focus, with the primary objectives of enhancing yield, minimizing costs, and mitigating environmental impacts. For instance, research findings indicate that meticulous control of reaction conditions can lead to improved purity of the resulting ionic liquids.

In terms of physical and chemical properties, phase behavior studies have revealed that at a temperature of 298.15 K, the phase behavior of ternary systems comprising [BMIM][PF6] along with water and various alcohols (such as methanol, ethanol, 2-propanol, etc.) is influenced by the size and structural characteristics of the alcohol molecules. Notably, certain systems exhibit miscibility at specific molar fractions.

Application Scenario

Electrochemistry Applications

Battery Electrolyte: This substance serves as an electrolyte in both lithium-ion and sodium-ion batteries, enhancing ion conductivity and electrochemical stability. Its use contributes to the efficient operation and longevity of these energy storage systems.

Electrodeposition: It functions as an electrolyte in the electrodeposition of tantalum chloride (TaCl₅). Research has demonstrated its ability to facilitate the gradual reduction of Ta(V) to metallic tantalum and low-valent chlorides, rendering it ideal for the production of corrosion-resistant coatings. This application highlights its utility in advanced material synthesis and surface engineering.

Electrochemical Sensor: In the realm of biosensors, composite modified electrodes incorporating nanogold, chitosan, and other materials utilize this substance to elevate detection sensitivity and stability, particularly in glucose oxidase-based sensors. This advancement is pivotal for enhancing the performance of diagnostic devices in medical and biological applications.

General Electrochemical Use: Within the broader field of electrochemistry, it finds application as an electrolyte or solvent in battery and capacitor research, playing a crucial role in the development of next-generation energy storage and conversion technologies.

Organic Synthesis

Green Solvent:This substance serves as an environmentally friendly alternative to traditional organic solvents, finding utility in various organic synthesis processes such as enzymatic ester synthesis and the Suzuki cross-coupling reaction. Its adoption enhances reaction efficiency and yield, contributing to more sustainable and effective synthetic methodologies. For instance, in the presence of a phase-transfer catalyst, a two-phase system comprising [BMIM]PF₆ and toluene can facilitate the Beckmann rearrangement of cyclohexanone oxime to caprolactam, achieving a remarkable conversion rate of 99.7% and a selectivity of 98.9%.

Chromatographic Applications:It is employed as a mobile phase or stationary phase in advanced chromatographic techniques like gas chromatography and countercurrent chromatography. These applications leverage its unique properties to improve separation efficiency and resolution, making it invaluable in both analytical and preparative organic chemistry.

Extraction and Separation

Harnessing its exceptional dissolving and extraction capabilities, this substance enables the extraction of complex molecules from natural products. It plays a crucial role in separation processes within pharmaceutical chemistry, facilitating the isolation and purification of active compounds. This application underscores its potential in drug discovery and development, where the efficient extraction and purification of bioactive molecules are paramount.

Solid Phase Microextraction (SPME):Utilizing a PEG 20M composite coating, SPME has been optimized for the detection of o-chlorophenol and 4-nitrotoluene in water samples. This technique offers significant improvements in detection limits and reproducibility, making it a valuable tool for environmental monitoring and water quality assessment. The enhanced sensitivity and reliability of SPME with PEG 20M coating facilitate the accurate detection of trace contaminants, contributing to safer and cleaner water resources.

Biochemistry and Medicinal Chemistry

Alternative Organic Solvents: In enzyme-catalyzed reactions, this substance serves as an eco-friendly alternative to traditional organic solvents. It supports environmentally sustainable biocatalytic processes, such as asymmetric synthesis, by enhancing product formation rates and enantioselectivity. This application promotes green chemistry practices in biochemical research and industrial biotechnology.

Medicinal Chemistry: Within the realm of medicinal chemistry, it finds utility in the synthesis of drug intermediates and the extraction of complex molecules. Its use in these processes aids in the development of novel pharmaceuticals and the isolation of bioactive compounds from natural sources. By facilitating efficient and selective extractions, it contributes to the advancement of drug discovery and the optimization of synthetic routes for active pharmaceutical ingredients.