Cyclohexyldichlorophosphine: Properties, Synthesis & Applications

Cyclohexyldichlorophosphine is a highly reactive organophosphorus building block bearing two hydrolytically labile P–Cl bonds, making it an essential intermediate for the preparation of phosphine ligands, phosphoramidites, and a broad range of phosphorus-based compounds used in catalysis and materials science.

Chemical Name

Cyclohexyldichlorophosphine

Molecular Formula

C₆H₁₁Cl₂P

Molecular Weight

181.03 g/mol

Aladdin SKU

C281947

Strem Catalog Number

15-0800

Key Reactive Groups

Two P–Cl bonds (electrophilic phosphorus center)

Storage Conditions

Inert atmosphere, sealed, away from moisture

Chemical Structure and Physical Properties

Cyclohexyldichlorophosphine (molecular formula C₆H₁₁Cl₂P, MW 181.03 g/mol) belongs to the class of alkylphosphonous dichlorides, characterised by a trivalent phosphorus atom bearing one cyclohexyl substituent and two chlorine atoms. The phosphorus centre is strongly electrophilic due to the electron-withdrawing effect of the two P–Cl bonds, rendering the compound highly susceptible to nucleophilic attack by oxygen, water, and nitrogen nucleophiles.

The compound is typically described as a colourless to pale-yellow liquid at room temperature with a pungent odour. It fumes readily in moist air, generating hydrogen chloride gas upon hydrolysis. These properties necessitate careful handling under strictly anhydrous and inert-atmosphere conditions.

Synthesis and Key Reactions

Cyclohexyldichlorophosphine is most commonly prepared by the reaction of phosphorus trichloride (PCl₃) with cyclohexyl Grignard reagents (e.g., cyclohexylmagnesium chloride) or, alternatively, by the direct Friedel–Crafts-type phosphonation routes applicable to cycloaliphatic substrates. Industrial preparations frequently rely on the reaction of PCl₃ with cyclohexene in the presence of radical initiators or aluminium chloride catalysts, though the exact commercial synthesis route should be confirmed with the supplier.

Its principal chemical transformations include:

• Hydrolysis: Reaction with water yields cyclohexyldichlorophosphine oxide intermediates and ultimately cyclohexylphosphonic acid.
• Alcoholysis / aminolysis: Controlled addition of alcohols or amines allows stepwise substitution of the two P–Cl bonds to afford phosphonites, phosphonamidites, or bis(amino)phosphines.
• Reduction: Treatment with hydride reagents (e.g., LiAlH₄) converts the dichlorophosphine to cyclohexyldiphosphine or cyclohexy phosphine (H-substituted products).
• Organometallic coupling: Reaction with organolithium or Grignard reagents installs additional carbon substituents, enabling access to unsymmetrical dialkyl- or arylalkylphosphines.

Applications in Research and Synthesis

The bifunctional electrophilic phosphorus centre of cyclohexyldichlorophosphine makes it a versatile precursor in multiple fields:

• Ligand synthesis for transition-metal catalysis: The compound serves as a building block for secondary phosphines and chelating diphosphine ligands used in palladium-, rhodium-, and nickel-catalysed cross-coupling, hydroformylation, and asymmetric hydrogenation reactions.
• Phosphoramidite and nucleotide chemistry: Controlled aminolysis provides access to phosphoramidite intermediates relevant to oligonucleotide synthesis, though alternative P(III) sources are more common in automated DNA synthesis.
• Materials science and flame retardants: Cyclohexyl-substituted phosphorus compounds derived from this reagent find use as intermediates in the preparation of phosphorus-containing polymers and flame-retardant additives.
• Agrochemical and pharmaceutical intermediates: Phosphonic acid derivatives and phosphonamides accessible from cyclohexyldichlorophosphine appear in the synthetic routes of certain pesticidal and pharmaceutical active ingredients.

Researchers should note that the high reactivity of the P–Cl bonds requires strict exclusion of moisture and oxygen during all synthetic operations.

Safe Handling, Storage, and Regulatory Considerations

Cyclohexyldichlorophosphine is classified as a corrosive and moisture-sensitive reagent. Contact with water or humid air generates hydrogen chloride, posing a serious inhalation hazard. The following precautions are strongly recommended:

• Handle exclusively inside a well-ventilated fume hood or glovebox under an inert atmosphere (nitrogen or argon).
• Use appropriate personal protective equipment: chemical-resistant gloves (e.g., butyl rubber), safety goggles, and a lab coat.
• Store in tightly sealed containers under inert gas, in a cool, dry location away from moisture, bases, and alcohols.
• In the event of skin or eye contact, flush immediately with copious amounts of water and seek medical attention.
• Dispose of waste in accordance with local regulations governing organophosphorus and corrosive chemical waste.

Researchers should consult the full Safety Data Sheet (SDS) provided by Aladdin Scientific (SKU C281947) before use. Regulatory classification and transport requirements may vary by jurisdiction.

Frequently asked questions

What is Cyclohexyldichlorophosphine used for in the laboratory?

Cyclohexyldichlorophosphine is primarily used as a reactive intermediate for synthesising phosphine ligands, phosphonites, phosphoramidites, and other organophosphorus compounds. It is particularly valued in transition-metal catalyst development and in the preparation of phosphorus-containing materials.

How should Cyclohexyldichlorophosphine be stored to maintain stability?

The reagent must be stored under an inert atmosphere (nitrogen or argon) in tightly sealed containers, in a cool, dry location. Exposure to moisture or air causes rapid hydrolysis and generation of corrosive HCl gas, degrading the material.

What safety hazards are associated with Cyclohexyldichlorophosphine?

The compound is corrosive and reacts vigorously with water and moisture to produce hydrogen chloride, which is toxic by inhalation. It should be handled exclusively in a fume hood or glovebox with appropriate personal protective equipment, including chemical-resistant gloves and eye protection. Full SDS review before use is mandatory.

Can Cyclohexyldichlorophosphine be used to prepare chiral phosphine ligands?

Yes, the two reactive P–Cl bonds of cyclohexyldichlorophosphine allow sequential substitution with chiral or prochiral nucleophiles, enabling construction of phosphine ligands with defined stereochemistry. The cyclohexyl group also contributes steric bulk that can influence enantioselectivity in catalytic applications.

What is the Aladdin Scientific SKU for Cyclohexyldichlorophosphine?

Cyclohexyldichlorophosphine is available from Aladdin Scientific under SKU C281947, also corresponding to Strem Catalog Number 15-0800.

References

1. Quin, L. D. A Guide to Organophosphorus Chemistry. Wiley-Interscience, 2000.
2. Strem Chemicals Catalog, Entry 15-0800, Cyclohexyldichlorophosphine.
3. Imamoto, T. Phosphine Ligands in Asymmetric Catalysis. In Comprehensive Asymmetric Catalysis, Jacobsen, E. N.; Pfaltz, A.; Yamamoto, H. Eds., Springer, 1999.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.