Chemical Identity and Physical Properties

1-Butyl-4-methylpyridinium Bromide is a quaternary nitrogen salt formed by the N-alkylation of 4-methylpyridine with 1-bromobutane. The compound belongs to the family of pyridinium-based ionic liquid precursors, which are characterized by a positively charged nitrogen-containing aromatic ring balanced by a bromide counterion.

The salt is typically a solid or low-melting crystalline material at room temperature. Its molecular formula is C₁₀H₁₆BrN, yielding a molecular weight of approximately 242.15 g/mol. As a hygroscopic material, it should be handled and stored under dry conditions to prevent moisture absorption that could alter its physical state and purity.

The compound is generally soluble in polar solvents such as water, methanol, and acetonitrile, which is characteristic of ionic salts with a delocalized cationic charge. Its melting point and other thermophysical data should be verified against the product Certificate of Analysis (CoA) provided with each lot.

Synthesis and Anion Metathesis

1-Butyl-4-methylpyridinium Bromide is most commonly synthesized via a straightforward quaternization reaction: 4-methylpyridine is reacted with 1-bromobutane under neat conditions or in an appropriate solvent at elevated temperature. The reaction proceeds via an S_N2 mechanism, with the nucleophilic pyridine nitrogen attacking the terminal carbon of the bromoalkane chain.

The resulting bromide salt serves as a key intermediate for the preparation of a wide range of ionic liquids with different anions. Anion metathesis reactions — using silver salts, ion-exchange resins, or direct acid-base neutralization — allow researchers to exchange the bromide anion for more complex, less coordinating anions such as hexafluorophosphate (PF₆⁻), bis(trifluoromethylsulfonyl)imide (NTf₂⁻), or tetrafluoroborate (BF₄⁻). These derived ionic liquids often exhibit lower melting points and improved electrochemical stability compared to the parent bromide salt.

Researchers should monitor reaction completion via NMR spectroscopy and verify bromide content in the final ionic liquid product to ensure thorough anion exchange, as residual bromide can negatively affect electrochemical window measurements.

Applications in Research

Electrochemistry and Energy Storage: Pyridinium-based ionic liquids derived from 1-Butyl-4-methylpyridinium Bromide are investigated as electrolytes or electrolyte additives in batteries, supercapacitors, and electrodeposition processes. The tunability of the ionic liquid's physicochemical properties makes it attractive for optimizing ion transport and electrochemical stability windows.

Catalysis and Organic Synthesis: Ionic liquids based on the 1-butyl-4-methylpyridinium cation have been explored as reaction media or co-catalysts in various organic transformations, including Diels-Alder reactions, esterifications, and transition-metal-catalyzed coupling reactions. The structured ionic environment can influence reaction selectivity and rate.

Extraction and Separation Science: The ability to engineer the hydrophilicity or hydrophobicity of derived ionic liquids through anion selection enables their use in liquid-liquid extraction, supported ionic liquid membranes, and chromatographic stationary phases for separation of target analytes.

Green Chemistry Platform: As an ionic liquid precursor, 1-Butyl-4-methylpyridinium Bromide aligns with green chemistry principles by enabling the design of low-volatility, recyclable reaction media that can reduce reliance on conventional volatile organic solvents.

Handling, Safety, and Storage Guidelines

Personal Protective Equipment (PPE): When handling 1-Butyl-4-methylpyridinium Bromide, wear appropriate personal protective equipment including chemical-resistant gloves, laboratory coat, and safety goggles. Avoid inhalation of dust or aerosols, particularly when weighing or transferring the material.

Storage: Store the compound in a tightly sealed container in a cool, dry, well-ventilated area away from moisture, heat, and incompatible materials such as strong oxidizers. Due to its hygroscopic nature, use desiccant in storage areas and minimize exposure to ambient air during handling.

Stability: The compound is expected to be stable under recommended storage conditions. Users should consult the Safety Data Sheet (SDS) and Certificate of Analysis (CoA) supplied with the product for lot-specific stability and purity data.

Disposal: Dispose of waste material in accordance with local, regional, and national regulations. Do not pour down the drain without verifying local regulatory compliance for ionic liquid waste streams.

Note: Specific GHS hazard classifications, H-statements, and P-statements should be confirmed in the product SDS. Review flags have been added where specific regulatory data are not confirmed in the source material.

Quality Specifications and Ordering Information

Purity and Grade: Aladdin Scientific supplies 1-Butyl-4-methylpyridinium Bromide (SKU: B120511) for research use. Researchers should consult the product page or contact Aladdin Scientific directly for the current purity specification, available pack sizes, and lot-specific Certificate of Analysis (CoA).

Analytical Characterization: The identity and purity of each lot are typically confirmed by standard analytical techniques including ¹H NMR, elemental analysis, and/or HPLC. Residual solvent and water content may also be reported. Detailed specifications are available upon request or via the product CoA.

Ordering: To order or request bulk pricing, researchers and procurement teams may contact Aladdin Scientific through the official website or authorized distributors. Ensure you reference SKU B120511 when placing orders to receive the correct product.