Trioctylphosphine

Trioctylphosphine (TOP) (CAS 4731-53-7) is a long-chain tertiary alkylphosphine, often referred to as a "workhorse" in the field of nanomaterials chemistry. It presents as a colorless to pale yellow, oily, and slightly viscous liquid with a very mild phosphine odor compared to its shorter-chain counterparts. The extended octyl chains grant TOP exceptional thermal stability, extremely low volatility, and high lipophilicity. These properties make it indispensable for its dual role as a high-boiling, non-coordinating solvent and a capping ligand in the high-temperature synthesis of semiconductor quantum dots (QDs) and other metal nanocrystals.

Basic Information of TOP

CAS No.:	4731-53-7
EC No.:	225-234-2
Linear Formula:	C24H51P
Molecular Weight:	370.64
Appearance:	Colorless to pale yellow, oily liquid
Odor:	Mild, faint phosphine/garlic-like
Melting Point:	30°C
Boiling Point:	284-291 °C50 mm Hg(lit.)
Density:	0.831 g/mL at 25 °C(lit.)
Solubility:	Insoluble in water; excellent solubility in non-polar solvents, oils, and high-boiling ethers.
Flash Point:	297 °F
RIDADR:	UN 2845 4.2/PG 1
Chemical Structure:

Application Overview

Trioctylphosphine is a highly specialized reagent whose role is often non-negotiable in specific high-end chemical and materials science applications:

• Nanocrystal Synthesis (Quantum Dots): TOP is crucial for the synthesis of Cadmium Selenide (CdSe), Lead Sulfide (PbS), and other II-VI/IV-VI quantum dots. It acts as a solvent and as a surface-capping ligand that controls the growth, size, and shape uniformity of the nanocrystals during high-temperature injection synthesis.

• High-Temperature Organic Synthesis: Its extremely high boiling point and low vapor pressure make it an ideal, non-volatile ligand for metal-catalyzed reactions (e.g., cross-couplings) that require reaction temperatures exceeding $200\text{ °C}$.

• Reducing Agent: Used in specialized reductions (e.g., Mitsunobu reaction, Staudinger reduction) where its solubility in highly non-polar or oily media is necessary, or where a non-volatile reagent is required for post-reaction purification.

• Phase-Transfer and Extraction: The high lipophilicity of TOP and its oxidized derivative (TOPO) makes them excellent agents for the extraction and separation of metal ions in solvent extraction processes, particularly in rare-earth metal processing.

• High-Temperature Stability Verification: Our Certificate of Analysis (CoA) includes data verifying the material's thermal stability profile at typical nanocrystal synthesis temperatures (e.g., $300\text{ °C}$), providing assurance of performance and minimizing the risk of thermal degradation during your process.

• Advanced Packaging for Trace Purity: TOP is shipped in precision-cleaned, inert gas-blanketed containers with specialized high-barrier seals. This meticulous handling prevents oxygen or moisture contamination, which is paramount for maintaining the material's reactivity and surface-binding efficacy.

Hazards Classification

• GHS Classification: Pyr. Liq. 1 (GHS01), Skin Corr. 1B (GHS05), Eye Dam. 1 (GHS05)

• Hazard Statements: Catches fire spontaneously if exposed to air; Causes severe skin burns and eye damage.

• UN Number: UN 2845

• Hazard Class: 4.2 (Spontaneously combustible)

• Packing Group: I