Tetrabutyl-ammonium hydrogensulfate forms part of the quaternary ammonium salt family, specifically showing up as a single-organic-cation paired with a hydrogensulfate anion. The chemical formula appears as C16H37NO4S, while its structure reveals four butyl chains around a central nitrogen atom tied to the sulfate group. What stands out is its relatively large, bulky organic cation, giving the material properties not typically found in smaller ammonium salts. Out in the lab or production facility, you'll see it sold as white or off-white solid flakes, crystalline powders, sometimes in the form of granules or even pearls—occasionally as a liquid when dissolved, but always a robust and usable raw material. The HS Code that covers this chemical typically falls under 292390, marking it as a subject of interest for customs, import, and hazard cataloging.
Tetrabutyl-ammonium hydrogensulfate shows real staying power as a phase transfer catalyst and supporting electrolyte, carving its niche in organic synthesis, chemical manufacturing, and pharmaceutical processes. In one of my own projects, switching to this salt made two-phase reactions more manageable, letting organic solutes cross boundaries—an essential twist for yield and efficiency. That's the heart of phase transfer: breaking the usual solubility limits, smoothing the path for reactions in water-organic systems. I’ve watched chemists return to this material when reactions stall, grateful for its overlooked but crucial role in breaking stubborn barriers in synthesis.
Tetrabutyl-ammonium hydrogensulfate shows up as a solid at room temperature with a melting point falling into a comfortable, controllable range—usually between 100°C and 110°C. The material often appears as dense flaky crystals or pearlescent powder, reflecting its purity and suitability for direct use in chemical processes. The molecular weight sits at roughly 339.54 g/mol, and it typically carries a density around 1.08 g/cm³, values which matter when handling in bulk or dosing by volume. Since the salt shows hygroscopic tendencies, it will absorb moisture from the air, so storage in tightly sealed containers is essential, as any chemist handling kilogram runs quickly learns. Solubility fits the “dual-nature” role: freely dissolving in both polar solvents like water and less polar ones such as alcohols, expanding its use across varied systems. My own experience storing this chemical taught me the importance of humidity control—not only does moisture spoil the flowability, but it can trigger slow decomposition and reduction in reactivity, affecting final yields.
The structural story reflects why this salt works in so many places. With four butyl groups splaying out from a charged core, the molecular bulk helps push the boundaries where smaller ammonium salts struggle. Each butyl chain gives extra hydrophobic character, meaning it mixes well with both organic solutions and aqueous ones when broken up. In the lab, visualizing this big, soft cation nudging solutes from water into organic solvents anchoring chemical change deepens respect for chemical design. The sulfate end brings the necessary acid-base reactivity and ion-pair capability—the foundation for most catalytic applications.
Grade matters: industrial, analytical, or pharmaceutical preparations differ in specified purity, with high-end uses requiring 98% or greater, sometimes demanding HPLC or electrochemical analysis for quality. Color leans white, but off-white or faint beige tones show up without much issue for most uses. Handling these crystals or flakes, even in large quantities, poses minimal hazard under standard chemical practice. Yet, this is a strong irritant—glove use is mandatory, and dusts should never be inhaled. The pungent, slightly ammoniacal odor marks it for seasoned chemists, a subtle warning to limit open-air exposure. Whether you encounter technical grade bags on a warehouse pallet or small bottles labeled for the lab, clarity on contamination and water content plays a core role in performance.
Working with tetrabutyl-ammonium hydrogensulfate means taking usual chemical safety steps seriously. The compound presents moderate hazards—risk of irritation to the skin, eyes, and respiratory tract, and significant environmental impact if mismanaged. In laboratory settings, goggles and nitrile gloves prevent contact injuries, while weighing inside ventilated hoods or gloveboxes avoids dust inhalation. Environmental persistence comes up in regulatory documents, since quaternary ammonium salts may disrupt aquatic environments when released—the chemical's popularity brings responsibility for containment and proper waste disposal. Incineration or controlled chemical treatment remains preferred for wastes. In my past roles, even minor spills called for fast brooming—otherwise, slippery residues or static-laden powders attach to everything in reach. Safety sheets provided by producers offer detailed storage, handling, and transport requirements, worth reading closely because regulations around toxicological and OEL (occupational exposure limits) shift as research develops.
Market supply comes from specialized chemical vendors, who often tailor batch sizes to fit from gram-scale research to multi-ton industrial runs. Raw materials for production—typically butylamine and sulfuric acid—set the base, but the quality of these reagent streams directly affects the salt’s purity and bulk properties. During procurement, sourcing from REACH-compliant or otherwise regulated suppliers provides peace of mind about trace contaminants and batch traceability. In several procurement cycles, I found that price swings and raw supply disruptions for quaternary ammonium reagents affect lead times—placing early orders and verifying technical certificates can preempt production headaches down the line.
To keep both safety and environmental concerns at bay, adopting closed-system transfers, investing in on-site neutralization or recycling for waste streams, and training staff on both acute and chronic toxicity features should figure in any serious chemical handling operation. For researchers, pilot-scale tests addressing moisture content, reactivity drift, and impurity control promote reproducible outcomes through the scale-up process. Open communication with chemical suppliers to update on tighter specs or new regulatory changes also helps align both research and production with evolving standards. For those dealing with regulatory filings, keeping accurate records on HS Codes, batch traceability, and safety data improves both compliance and transparency, bringing peace of mind and smoothing customs and audit processes.
