Tetraoctylphosphonium Bromide

Tetraoctylphosphonium Bromide (TOPB) (CAS 23906-97-0) is a specialized quaternary phosphonium salt characterized by four long C₈ octyl chains. It typically appears as a white to off-white, waxy crystalline solid with minimal odor. The extended alkyl chains confer exceptional lipophilicity and high molecular weight to the phosphonium cation. This makes TOPB highly effective as a Phase-Transfer Catalyst (PTC) for reactions involving extremely non-polar organic media, and crucially, as a superior extractant and phase separator for complex metal ions, particularly in the demanding fields of hydrometallurgy and rare-earth element (REE) recovery. TOPB's thermal stability also makes it a key precursor for advanced ionic liquids.

Basic Information of TOPB

CAS No.:	23906-97-0
EC No.:	245-935-7
Linear Formula:	C32H68BrP
Molecular Weight:	563.76
Appearance:	White to off-white crystalline solid/waxy powder
Melting Point:	38-43 °C(lit.)
Solubility:	Negligible in water; highly soluble in non-polar solvents (hexane, toluene, oils), alcohol, and chloroform.
Flash Point:	>230 °F
RIDADR:	UN 3261 8/PG 3
Chemical Structure:

Application Overview

TOPB's pronounced lipophilicity makes it ideal for specialized applications that require strong partitioning into organic or non-polar phases:

• Solvent Extraction (Hydrometallurgy): A primary component in advanced liquid-liquid extraction systems for the separation and recovery of valuable metals, particularly heavy metals, platinum-group metals (PGMs), and rare-earth elements (REEs), where its large, lipophilic cation forms stable, easily extractable ion pairs.

• Phase-Transfer Catalyst (PTC): Used as a highly effective PTC in reactions involving highly non-polar organic solvents, where standard shorter-chain catalysts (like TBAB) are insufficiently soluble to bridge the two phases effectively.

• Ionic Liquid Precursor: The tetraoctylphosphonium cation is synthesized into various advanced ionic liquids (ILs), imparting very high thermal stability, exceptional hydrophobicity, and low viscosity to the resulting IL for specialized high-temperature or non-aqueous electrochemical applications.

• Polymer and Materials Science: Employed as a non-volatile stabilizer or additive in polymers and resins, often to enhance compatibility or to introduce specific ionic properties into non-polar matrices.

• Metal-Free Purity Certification: Our TOPB is certified with guaranteed ultra-low levels of transition metal and heavy metal contamination (<5 ppm for key elements). This is non-negotiable for solvent extraction used in high-purity rare-earth or PGM recovery, ensuring zero cross-contamination.

Hazards Classification

• GHS Classification: Skin Corr. 1B (GHS05), Eye Dam. 1 (GHS05)

• Hazard Statements: Causes severe skin burns and eye damage.

• UN Number: UN 3261

• Hazard Class: 8 (Corrosive substances)

• Packing Group: III