Tetrabutylphosphonium acetate belongs to a family of organic phosphonium salts where a central phosphorus atom bonds to four butyl groups and an acetate anion. This chemical has the molecular formula C18H39O2P, with a molecular weight that lands near 318.48 g/mol. The substance appears in several forms, with color ranging from pale white to off-white depending on purity. Physical appearances include solid, powder, crystalline flakes, and sometimes pearls. Less frequently, this material is offered as a highly concentrated liquid or suspension. If someone has handled ionic liquids and related phosphonium salts before, tetrabutylphosphonium acetate brings to mind that unmistakable combination of smooth texture and faint chemical odor.
Looking closely at the structure, the phosphonium cation features a central phosphorus atom carrying a positive charge surrounded by four long butyl chains, which lend a greasy, slippery feel in solid and powdered forms. The acetate anion balances the charge and brings a touch of hydrophilicity, making this salt notably more soluble in water and polar organic solvents than many alkyl phosphonium relatives. At room temperature, most batches present as a waxy or granular powder, and the material transitions to a viscous liquid above roughly 50-60°C. Crystal habits tend toward irregular flakes, and under high magnification, one can spot the layered morphology characteristic of salts capable of easy redissolution.
Most reputable measurements put density in the range of 0.94 to 1.02 g/cm³ at 20°C, close to the lighter end for organophosphorus chemicals, which makes storage and shipping easier. Tetrabutylphosphonium acetate dissolves freely in water, ethanol, and many common solvents, which suggests wide potential for solution-phase chemistry and industrial extractions. The raw material status means that users end up working with flakes, powder, or pearls, each suitable for different dosing and process requirements. Solid material typically comes in tamper-proof packaging, sometimes vacuum-sealed, because of its tendency to absorb moisture from ambient air.
CAS number provides a unique identifier, while the Harmonized System (HS) code sorts it under organic chemicals—used to clear customs and meet international trade requirements. Based on experience with export paperwork, this chemical often falls within the HS code 2921.19, tying it to quaternary ammonium and phosphonium compounds. Standard product specs cover purity (often 98% or higher), melting range, residual water, color, and sometimes trace impurity content. Bulk packages run from small laboratory bottles up to drums; each label must provide formula, density, and basic physicochemical profile to comply with both REACH and GHS guidelines.
Tetrabutylphosphonium acetate carries its risks like any strong organic salt. Direct skin contact or accidental ingestion leads to irritation and possible toxicity, as both the phosphonium cation and acetate anion are active participants in biological systems. Safety data emphasize handling with gloves and goggles in a ventilated area, with proper labeling so everyone on the shop floor recognizes its hazardous status. Powder forms generate dust hazards when decanted too fast, and liquid or dissolved forms can seep through fabric gloves. Even with seemingly ordinary appearance, it pays to consult a chemical safety datasheet regularly—spills need containment with inert absorbents, and disposal routes should follow local environmental protocols to avoid aquifer contamination.
Tetrabutylphosphonium acetate acts as a workhorse in organic synthesis, ionic liquid development, phase transfer catalysis, and materials science. Because its gentle basicity and good ion mobility, researchers and chemical engineers value it for tasks ranging from extraction of metal ions to enzyme immobilization and solubilization of lignocellulosic biomass. It serves as a building block—raw material—for new phosphonium ionic liquids, which have become crucial in green chemistry for their low volatility and tunable properties. Large-scale users should focus on verifying product traceability, since off-spec raw materials ruin downstream processes and impact yields dramatically in specialty chemical manufacture.
The tetrabutylphosphonium core gives the salt bulk and hydrophobic character, while the acetate anion tugs in the opposite direction with a strong dipole and polar character. This dual behavior enhances miscibility across solvent types. The molecular structure—four butyl arms and a phosphonium center—means that material resists oxidative decomposition better than lower alkyl phosphonium salts. Such stability factors into decisions about storage time and compatibility with other chemical reagents.
Tetrabutylphosphonium acetate proves versatile because it arrives in so many forms. Flake and crystalline states offer easy measurement and dissolution in laboratory-scale syntheses, while powder or pearl grades suit large-scale applications where metering with dosing equipment is needed. The solid state presents minimal risk of accidental air release, whereas liquid or solution grades ease mixing and dilute dosing. Volume by liter or kilogram depends on buyer needs, and consistent lot-to-lot properties help avoid process interruptions. End users pay close attention to factors like clumping, moisture uptake, and color shift, all of which provide early warning for improper storage or age degradation.
Accurate, clear hazard communication proves critical for this chemical. Regulatory labels must flag it as hazardous, with statements covering safe handling, fire risk, and first aid measures. Experience in plant settings shows that compliance with these measures keeps incident rates down. In the push toward safer materials, some researchers aim to tweak the butyl chain length or swap acetate for other anions, searching for better performance with less risk. For now, proper storage, robust personal protective gear, and strict batch validation offer the best insurance against accidents and compromised research.
