4,5-Bis(diphenylphosphino)-9,9-dimethylxanthene

Name: 4,5-Bis(diphenylphosphino)-9,9-dimethylxanthene
Other Names: Xantphos; 9,9-dimethyl-4,5-bisdiphenylphosphinoxanthene; 4,5-bisdiphenylphosphino-9,9-dimethylxanthene; dimethylbisdiphenylphosphinoyloxanthene
English Other Names: XANT PHOS; Dimethylbisdiphenylphosphinoxanthene; (9,9-Dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane); 9,9-DIMETHYL-4,5-BIS(DIPHENYLPHOSPHINO)XANTHENE
CAS No.: 161265-03-8
EINECS No.: 605-249-4
Chemical Formula: C₃₉H₃₂OP₂
Molecular weight 578.62
ikB InChI=1S/C39H32OP2/c1-39(2)33-25-13-19-29(35(33)40-30-20-14-26-34(39)36(30)41(31-21-9-5-3-6-10-21)32- 22-11-7-4-8-12-22)37(41)27-15-17-23(18-16-27)42(2,3)38(33)28-24-14-10-9-13-25(28)37/h3-20,25-26H,1-2H3
InChIKey CXNIUSPIQKWYAI-UHFFFAOYSA-N
Density: 1.21 g/cm³ (crystals)
Boiling Point: 665.7±55.0 °C (predicted, 760 mmHg)
Flash Point: 450 °C (or 449.9 °C)
Water Solubility: Insoluble in water
Vapor Pressure: 7.61×10⁻¹⁷ mmHg (25°C)
Storage Conditions: Store protected from light, in a sealed, dry place at room temperature; under inert gas protection.
Sensitivity: Sensitive to air and moisture (inert atmosphere recommended)
Appearance: White to pale yellow crystalline powder
Specific Gravity: 1.21
Color: White to pale yellow
BRN: Undetermined
MDL Number: MFCD00191819
Hazard Symbol: Xi (Irritant)
Risk Terms: R37 (Irritant to Respiratory System), R20/22 (Harmful if Inhaled or Ingested)
Safety Terms S26 (If contact with eyes occurs, immediately rinse with plenty of water and consult a doctor), S37/39 (Wear appropriate gloves and goggles or a mask)

Customs Code 2931.39 (Organophosphorus Compounds)

Properties: 4,5-Bis(diphenylphosphine)-9,9-dimethyloxanthracene is an organophosphorus compound derived from oxanthracene heterocycles, belonging to bidentate ligands. The most notable characteristic of this compound is its exceptionally wide bite angle, approximately 111°, with a flexibility range of 97°–135°. This unique spatial configuration gives it excellent performance in catalytic reactions.

This compound is a white to pale yellow crystalline powder at room temperature and pressure, with a melting point of 224–228°C. It is relatively stable in air and can be stored for a long time. It is readily soluble in organic solvents such as dichloromethane, but insoluble in water and petroleum ether. This compound exhibits good chemical and thermal stability, with a boiling point as high as 665.7°C.

As an electron-rich ligand, Xantphos possesses significant steric hindrance, enabling it to effectively stabilize metal centers and activate substrates in transition metal-catalyzed reactions.

Applications
4,5-Bis(diphenylphosphino)-9,9-dimethyloxanthracene is primarily used as a ligand in the following areas:
* Coupling Reactions: Widely used as a highly efficient ligand in palladium-catalyzed Suzuki, Negishi, Stille, and Heck coupling reactions.
* Buchwald-Hartwig Coupling Reactions: A commonly used ligand in Buchwald-Hartwig amination reactions for the preparation of aromatic amines from aryl halides or aryl sulfonates.
* Hydroformylation Reactions: Used for the hydroformylation of alkenes; its wide bite angle characteristic enhances reaction selectivity and activity.
* C-N Cross Coupling: Used in palladium-catalyzed C-N cross coupling reactions to synthesize heterocyclic compounds.
* Pharmaceutical Intermediates: Used as an organic reagent and pharmaceutical intermediate.
* OLED Materials: Used for material research and preparation of organic light-emitting diodes (OLEDs). Preparation Method 1: Lithification Method (Traditional Method)
Raw Materials: 9,9-Dimethyloxanthracene, sec-butyllithium (or n-butyllithium), diphenylphosphine chloride, N,N,N’,N’-tetramethylethylenediamine (TMEDA)
Steps:

Under argon protection, dissolve 9,9-dimethyloxanthracene and TMEDA in methyl tert-butyl ether (MTBE).

Slowly add the sec-butyllithium solution dropwise at low temperature (6-10°C), stirring for 14-16 hours to achieve double lithiation.

Slowly add diphenylphosphine chloride dropwise at 10-20°C, controlling the mild exothermic reaction.

After stirring at room temperature for 5 hours, quench the reaction with methanol.

Filter to obtain the product, wash successively with MTBE, methanol, and water, and dry to obtain a white solid.

Yield: Approximately 77-88% Method 2: High-Temperature Condensation Method (Improved Method)

Raw Materials: Bis(2-diphenylphosphine) ether, acetone, trifluoromethanesulfonic acid

Steps:

Under argon protection, dissolve bis(2-diphenylphosphine) ether in toluene.

Add trifluoromethanesulfonic acid and acetone.

Heat to 150°C and react for 16 hours.

After cooling, extract, dry, and recrystallize to obtain the target product.

Yield: Approximately 90%

Safety Information

Hazard Overview: Solid, severely irritating to eyes and respiratory tract.

GHS Classification:

Serious Eye Injury/Eye Irritation: Category 2A

Specific Target Organ Toxicity – Single Exposure (Respiratory Irritation): Category 3

First Aid Measures:

Inhalation: Move patient to fresh air; if breathing stops, perform artificial respiration.

Skin Contact: Wash with soap and plenty of water.

Eye Contact: Rinse immediately with plenty of water and seek medical attention.

Ingestion: Rinse mouth with water; do not induce vomiting; seek immediate medical attention. Protective Measures:
Wear an N95 dust mask and chemical protective gloves.
Use goggles or a face shield to protect eyes and face.
Handle in a well-ventilated environment.
Storage Requirements:
Store in a cool, dry, and dark place.
Store at room temperature.
Recommended storage under an inert gas atmosphere (such as nitrogen or argon).
Incompatible Materials: Strong oxidizers.
Disposal: Dispose of any remaining or unrecovered solutions to a professional disposal company.