XPhos Pd G4 is a fourth-generation palladium catalyst widely used in organic synthesis, particularly in cross-coupling reactions like Suzuki-Miyaura and Buchwald-Hartwig amination. This catalyst is known for its high stability, efficiency, and selectivity, making it a valuable tool in pharmaceutical, material science, and fine chemical industries.
This topic explores the CAS number, chemical properties, synthesis, applications, and safety considerations of XPhos Pd G4.
What Is XPhos Pd G4?
Definition and Significance
XPhos Pd G4 is an advanced palladium catalyst featuring the XPhos ligand, known for its electron-rich and sterically hindered properties. The G4 (fourth-generation) version has further improvements in reactivity, solubility, and substrate compatibility compared to previous generations.
CAS Number of XPhos Pd G4
The CAS (Chemical Abstracts Service) number is a unique identifier assigned to every chemical substance. The CAS number for XPhos Pd G4 ensures accurate reference in scientific research and industrial applications.
Chemical Properties of XPhos Pd G4
Molecular Structure
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Core Metal: Palladium (Pd)
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Ligand System: XPhos (bulky biaryl phosphine ligand)
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Oxidation State of Pd: Typically +2
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Reactivity: Highly reactive under mild conditions
Physical Properties
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Appearance: Solid powder or crystalline form
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Color: Yellow to brown (depending on purity)
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Solubility: Soluble in organic solvents like toluene, THF, and dichloromethane
Synthesis of XPhos Pd G4
The synthesis of XPhos Pd G4 involves the coordinating of an XPhos ligand with a palladium source. The key steps include:
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Ligand Coordination: XPhos ligand reacts with Pd(II) or Pd(0) precursors.
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Purification: Recrystallization or chromatography is used to achieve high purity.
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Characterization: Techniques like NMR, IR, and mass spectrometry confirm the compound’s structure and purity.
Applications of XPhos Pd G4 in Organic Synthesis
1. Suzuki-Miyaura Cross-Coupling Reactions
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Forms carbon-carbon (C-C) bonds between aryl or vinyl halides and boronic acids.
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Produces biaryl compounds, crucial in pharmaceuticals, agrochemicals, and material science.
2. Buchwald-Hartwig Amination
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Facilitates the formation of C-N bonds between amines and aryl halides.
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Widely used in drug discovery and polymer chemistry.
3. Heck and Sonogashira Reactions
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Enables C-C and C≡C bond formations, important in complex molecule synthesis.
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Applied in the production of fine chemicals and advanced materials.
4. Industrial and Pharmaceutical Applications
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Plays a key role in the synthesis of active pharmaceutical ingredients (APIs).
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Used in OLED materials and conductive polymer production.
Advantages of XPhos Pd G4 Over Other Catalysts
1. High Efficiency and Selectivity
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Requires lower catalyst loading compared to earlier versions.
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Minimizes side reactions, leading to higher yields and purity.
2. Greater Stability
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Resistant to air and moisture, reducing degradation over time.
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Can be used under ambient conditions without significant loss of activity.
3. Broad Substrate Compatibility
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Works with electron-rich, electron-poor, and sterically hindered substrates.
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Enables reactions in mild conditions, preserving sensitive functional groups.
Comparison: XPhos Pd G4 vs. Other Palladium Catalysts
| Catalyst | Ligand Type | Advantages | Common Applications |
|---|---|---|---|
| XPhos Pd G4 | Biaryl phosphine | High stability, low catalyst loading | Suzuki, Buchwald-Hartwig, Heck |
| XPhos Pd G2 | Biaryl phosphine | Good solubility, improved activity | Suzuki, Buchwald-Hartwig |
| Pd(PPh₃)₄ | Triphenylphosphine | General-purpose, easy to handle | Suzuki, Heck |
| Pd(OAc)₂ + Ligand | Variable ligands | Customizable reactivity | General cross-coupling |
Handling and Safety Precautions
1. Storage Conditions
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Store in a dry, inert atmosphere (e.g., nitrogen or argon).
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Keep at room temperature, away from moisture and air.
2. Handling Procedures
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Use protective gloves, lab coats, and safety goggles.
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Work in a fume hood to minimize exposure to airborne ptopics.
3. Disposal Considerations
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Dispose of catalyst waste according to hazardous waste regulations.
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Can be recycled or recovered for future use.
XPhos Pd G4 is a highly advanced palladium catalyst, offering superior stability, efficiency, and selectivity in organic synthesis. Its applications in cross-coupling reactions make it invaluable in pharmaceutical, material science, and fine chemical industries. Proper handling and storage ensure optimal performance and safety in both laboratory and industrial settings.