Tris(2-methylphenyl)phosphine
[CAS# 6163-58-2]

Identification

• Classification: Organic raw materials >> Organic phosphine compound
• Name: Tris(2-methylphenyl)phosphine
• Synonyms: Tri(o-tolyl)phosphine
• Molecular Formula: C₂₁H₂₁P
• Molecular Weight: 304.37
• CAS Registry Number: 6163-58-2
• EC Number: 228-193-9
• SMILES: CC1=CC=CC=C1P(C2=CC=CC=C2C)C3=CC=CC=C3C

Properties

• Melting point: 120-122 °C

Safety Data

• Hazard Symbols: GHS07;GHS09 Warning
• Risk Statements: H315-H319-H335-H400-H410-H413
• Safety Statements: P261-P264-P264+P265-P271-P273-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P391-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Skin sensitization	Skin Sens.	1	H317
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

Tris(2-methylphenyl)phosphine is an organophosphorus compound notable for its role as a versatile ligand in transition metal chemistry. Discovered in the early 1970s, this compound emerged from research aimed at developing new ligands that could offer enhanced stability and reactivity in various catalytic processes. The synthesis of tris(2-methylphenyl)phosphine involves the reaction of phosphorus trichloride with 2-methylphenyl lithium, followed by treatment with a base to yield the final phosphine product.

The compound's primary application lies in its function as a ligand in metal-catalyzed reactions. The 2-methylphenyl groups attached to the phosphorus center impart both steric and electronic effects that influence the behavior of the metal-ligand complex. This structural configuration enhances the compound's effectiveness in stabilizing transition metal centers, making it valuable in a variety of catalytic processes.

In hydrogenation reactions, tris(2-methylphenyl)phosphine is used to stabilize and activate metal catalysts, such as those based on palladium or platinum. The ligand's bulky substituents around the phosphorus atom create a shielded environment around the metal center, which helps to control the reactivity of the catalyst. This stabilization allows for more efficient hydrogenation of unsaturated compounds, including alkenes and alkynes, leading to high yields of saturated products.

The compound is also prominent in cross-coupling reactions, where it serves as a ligand for palladium and nickel catalysts. The steric effects provided by the tris(2-methylphenyl)phosphine group help to stabilize the metal-ligand complex, which enhances the selectivity and efficiency of the cross-coupling process. This application is particularly important in the synthesis of complex organic molecules, where precise control over the coupling process can lead to the formation of valuable chemical intermediates.

In addition to its role in hydrogenation and cross-coupling reactions, tris(2-methylphenyl)phosphine is used in various other catalytic processes, including hydroformylation and carbonylation. Its ability to stabilize metal centers and influence reaction pathways makes it a valuable tool in the development of new chemical methodologies and materials.

Research continues to explore new applications and improvements for tris(2-methylphenyl)phosphine. Advances in catalytic science and synthetic chemistry may uncover further uses for this ligand in emerging technologies and processes. As a result, tris(2-methylphenyl)phosphine remains a significant compound in both academic research and industrial applications.

References

2024. Anwendung von Organometallkatalysatoren in der API-Synthese. Organometallik in der Prozesschemie, 1.
DOI: 10.1007/978-3-031-52858-3_4

2024. Synthetic Transformations of Lappaconitine. Chemistry of Natural Compounds, 60(1).
DOI: 10.1007/s10600-024-04289-4

2024. Recent developments in the chemistry of Negishi coupling: a review. Chemical Papers, 78(5).
DOI: 10.1007/s11696-024-03369-7