2-(Dicyclohexylphosphino)-2'-methylbiphenyl
[CAS# 251320-86-2]

Identification

• Classification: Chemical reagent >> Organic reagent >> Phosphine ligand
• Name: 2-(Dicyclohexylphosphino)-2'-methylbiphenyl
• Synonyms: dicyclohexyl-[2-(2-methylphenyl)phenyl]phosphane
• Molecular Formula: C₂₅H₃₃P
• Molecular Weight: 364.50
• CAS Registry Number: 251320-86-2
• EC Number: 607-557-4
• SMILES: CC1=CC=CC=C1C2=CC=CC=C2P(C3CCCCC3)C4CCCCC4

Properties

• Melting point: 107-111 ºC
• Water solubility: insoluble

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H315-H317-H319-H335
• Precautionary Statements: P261-P264-P264+P265-P271-P272-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P333+P317-P337+P317-P362+P364-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
Skin sensitization	Skin Sens.	1A	H317

Discovory and Applicatios

2-(Dicyclohexylphosphino)-2'-methylbiphenyl is a noteworthy chemical compound in the field of organometallic chemistry, particularly valued for its role as a ligand in transition metal catalysis. Its discovery and applications have highlighted its utility in various catalytic processes, contributing to advancements in both research and industrial chemistry.

The compound was first introduced in the 1990s during a period of intensive research into novel phosphine ligands. The ligand features a biphenyl backbone with a dicyclohexylphosphino group attached at the 2 position of one of the biphenyl rings, and a methyl group attached at the 2' position. This design was aimed at combining the steric protection provided by the dicyclohexyl groups with the electronic influence of the methyl group, resulting in a ligand with unique properties.

The synthesis of 2-(Dicyclohexylphosphino)-2'-methylbiphenyl involves several key steps. The process typically starts with the preparation of the biphenyl core, which can be synthesized through coupling reactions of phenyl-containing precursors. The dicyclohexylphosphino group is then introduced via a reaction with a phosphorus-containing reagent, followed by the installation of the methyl group. The product is purified using standard techniques such as column chromatography to obtain the desired high-purity ligand.

One of the primary applications of 2-(Dicyclohexylphosphino)-2'-methylbiphenyl is in homogeneous catalysis. The ligand is used to create catalysts for a variety of reactions, including hydrogenation, hydroformylation, and cross-coupling reactions. The combination of the dicyclohexyl groups and the methyl group imparts distinctive steric and electronic effects, which can significantly influence the reactivity and selectivity of metal catalysts.

In hydrogenation reactions, 2-(Dicyclohexylphosphino)-2'-methylbiphenyl serves as a ligand in catalysts that facilitate the reduction of unsaturated compounds. The bulky nature of the dicyclohexyl groups helps stabilize the metal center and control the selectivity of the hydrogenation process, leading to improved yields and desired product formation.

The compound is also used in hydroformylation reactions, where it helps create catalysts for the conversion of alkenes into aldehydes. The presence of the dicyclohexylphosphino ligand can influence the efficiency and selectivity of the reaction, enabling the production of aldehydes with high precision.

In cross-coupling reactions, 2-(Dicyclohexylphosphino)-2'-methylbiphenyl acts as a ligand that enhances the formation of carbon-carbon bonds. The unique steric and electronic properties provided by the ligand contribute to higher yields and better selectivity in the synthesis of complex organic molecules.

The advantages of using 2-(Dicyclohexylphosphino)-2'-methylbiphenyl include its ability to provide a well-defined steric and electronic environment around the metal center, which can enhance catalytic performance. However, challenges associated with its use may include the need for careful optimization of reaction conditions to achieve the desired results and the potential for ligand deactivation under certain conditions.

Future research into 2-(Dicyclohexylphosphino)-2'-methylbiphenyl may focus on exploring new catalytic applications and optimizing the ligand’s performance in various processes. Researchers may also investigate modifications to the ligand structure to further enhance its properties and develop new derivatives with improved reactivity and selectivity.

References

2022. Palladium-Catalyzed Site-Selective Arylation of α,β-Unsaturated Carbonyl Compounds through a Ligand-Controlled Strategy. *Synlett*, 33(3).
DOI: 10.1055/s-0040-1719877

2014. Design and Development of Ligands for Palladium-Catalyzed Carbonylation Reactions. *Synthesis*, 46(12).
DOI: 10.1055/s-0033-1338635

2003. Insights into the Origin of High Activity and Stability of Catalysts Derived from Bulky, Electron-Rich Monophosphinobiaryl Ligands in the Pd-Catalyzed C-N Bond Formation. *Journal of the American Chemical Society*, 125(44).
DOI: 10.1021/ja037932y