Trihexylphosphine Oxide

Trihexylphosphine Oxide (THPO) (CAS 3084-48-8) is the stable, oxidized form of trihexylphosphine. It is typically a white to off-white, waxy solid or low-melting liquid with a minimal odor. Unlike its highly reactive phosphine precursor, THPO is a chemically and thermally robust compound. Its structure, featuring a highly polar P=O bond and three long lipophilic hexyl chains, gives it exceptional characteristics: it is a powerful extractant for metal ions (especially rare-earth metals) from aqueous solutions into organic phases, and it serves as an effective capping ligand/stabilizer in high-temperature nanomaterials synthesis due to its low volatility.

Basic Information of THPO

CAS No.:	3084-48-8
EC No.:	221-392-1
Linear Formula:	C18H39OP
Molecular Weight:	302.48
Appearance:	White to off-white waxy solid or low-melting liquid
Odor:	Low odor (minimal or non-existent phosphine/garlic notes)
Melting Point:	34-35 °C
Boiling Point:	163°C
Density:	0.864±0.06 g/cm3(Predicted)
Solubility:	Slightly soluble in water; highly soluble in organic solvents, oils, and non-polar media.
Chemical Structure:

Application Overview

THPO is particularly valuable in applications that rely on its highly polar P=O group combined with its excellent solubility in non-polar organic systems:

• Solvent Extraction (Rare Earths): A critical reagent in the hydrometallurgy industry for the highly selective liquid-liquid extraction and separation of metal ions, including rare-earth elements (REEs), from mining leachates and recycled materials.

• Nanomaterials Synthesis: Used as a stabilizing and surface-capping ligand in the high-temperature synthesis of semiconductor nanocrystals and quantum dots. Its low volatility and coordinating ability ensure controlled growth and stabilization of the particle surface.

• Specialty Polymer Additive: Employed as a non-volatile plasticizer, flame retardant, or processing aid in various non-polar polymer formulations, where its high molecular weight and thermal stability are advantageous.

• Organic Synthesis: Used as a strong Lewis base additive in specific organic reactions, often to sequester or coordinate to metal ions or acidic protons, thereby accelerating or modifying reaction pathways.

• Purity for Hydrometallurgy: Our THPO is certified for ultra-low metal contamination, a non-negotiable requirement for high-purity rare-earth separation processes where trace metals must be carefully managed to ensure the final purity of the extracted elements.

• Thermal Stability Verification: Every batch is tested and verified for its thermal decomposition profile, guaranteeing that the material maintains its structural integrity and functional efficacy when used in high-temperature operations, such as nanocrystal growth above 250°C.

Hazards Classification

• GHS Classification: Skin Corrosion (GHS05), Environmental Hazard (GHS09)

• Hazard Statements: Causes severe skin burns and eye damage; Toxic to aquatic life with long lasting effects.

• UN Number: N/A

• Hazard Class: N/A

• Packing Group: N/A