Introduction and Overview : Allyltributylphosphonium Bromide (CAS: 55894-18-3)

Allyltributylphosphonium Bromide is a quaternary phosphonium salt with the molecular formula C15H34BrP. It is an important compound in the field of organic synthesis and material science due to its role as a phase-transfer catalyst and intermediate in specialized reactions. This compound is particularly valued for its ability to facilitate reactions between immiscible phases and its stability under a wide range of conditions.


Chemical Identity and Properties

  • Chemical Name: Allyltributylphosphonium Bromide

  • CAS Number: 55894-18-3

  • Molecular Formula: C15H34BrP

  • Molecular Weight: ~341.31 g/mol

  • Appearance: Typically appears as a crystalline or powdered solid, often white to off-white.

  • Solubility: Soluble in polar solvents such as water, alcohols, and acetone; limited solubility in non-polar solvents.

Its structure features a tributylphosphonium cation with an allyl group, paired with a bromide anion. The allyl group provides additional reactivity in organic transformations, making it versatile in various synthesis pathways.


Applications

1. Phase-Transfer Catalyst (PTC)

One of the most notable uses of Allyltributylphosphonium Bromide is as a phase-transfer catalyst. PTCs enable reactions between compounds in different phases (e.g., organic and aqueous) by transporting reactive ions into the organic phase, thereby enhancing reaction rates and yields.

2. Intermediate in Organic Synthesis

The allyl functionality allows it to serve as a key intermediate in the preparation of more complex molecules, including:

  • Specialty polymers

  • Functionalized organic compounds

  • Organophosphorus derivatives

3. Materials Science

In some advanced material synthesis routes, phosphonium salts like Allyltributylphosphonium Bromide contribute to surface modification processes, ionic liquid development, and the preparation of functional monomers.


Advantages of Using Allyltributylphosphonium Bromide

  • Thermal Stability: Resistant to decomposition under moderate heating.

  • High Catalytic Efficiency: Speeds up heterogeneous reactions without needing extreme conditions.

  • Versatility: Applicable in a wide range of reactions, from polymerization to alkylation.


Safety and Handling

As with many quaternary phosphonium salts, careful handling is required:

  • Avoid inhalation of dust or vapors.

  • Use appropriate personal protective equipment (PPE) such as gloves and goggles.

  • Store in a cool, dry, well-ventilated place away from strong oxidizing agents.


Conclusion

Allyltributylphosphonium Bromide (CAS: 55894-18-3) is a highly valuable reagent and catalyst in organic and materials chemistry. Its unique structure, combining a phosphonium center with an allyl group, offers exceptional reactivity and versatility. From facilitating phase-transfer reactions to serving as a building block in specialty chemical synthesis, this compound continues to be a preferred choice in both laboratory research and industrial applications.