Tri-tert-butylphosphine tetrafluoroborate
[CAS# 131274-22-1]

Identification

• Classification: Organic raw materials >> Organic phosphine compound
• Name: Tri-tert-butylphosphine tetrafluoroborate
• Molecular Formula: C₁₂H₂₈P.BF₄
• Molecular Weight: 290.13
• CAS Registry Number: 131274-22-1
• EC Number: 672-603-2
• SMILES: [B-](F)(F)(F)F.CC(C)(C)[PH+](C(C)(C)C)C(C)(C)C

Properties

• Melting point: 261 °C

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H302-H314-H315-H318-H319-H332-H335
• Safety Statements: P260-P261-P264-P264+P265-P270-P271-P280-P301+P317-P301+P330+P331-P302+P352-P302+P361+P354-P304+P340-P305+P351+P338-P305+P354+P338-P316-P317-P319-P321-P330-P332+P317-P337+P317-P362+P364-P363-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2	H319
Serious eye damage	Eye Dam.	1	H318
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Skin corrosion	Skin Corr.	1B	H314
Skin corrosion	Skin Corr.	1C	H314
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

Tri-tert-butylphosphine tetrafluoroborate, chemically known as P(t-Bu)3 . HBF4, is an important phosphine reagent and ligand in the fields of synthetic and organometallic chemistry. The synthesis of tri-tert-butylphosphine tetrafluoroborate stems from the need for highly sterically hindered and electron-rich phosphine ligands to enhance reactivity and selectivity in transition metal catalyzed reactions. It is generated by the reaction of tri-tert-butylphosphine with tetrafluoroboric acid (HBF₄). This combination yields a stable crystalline salt that is easy to handle and incorporate into catalytic systems. Tri-tert-butylphosphine tetrafluoroborate consists of a phosphine (P(t-Bu)₃) coordinated with a tetrafluoroborate (BF₄⁻) anion. The bulky tert-butyl groups around the phosphorus atom provide significant steric hindrance, while tetrafluoroborate provides stability and solubility in polar solvents. This unique structure makes P(t-Bu)₃•HBF₄ an efficient ligand in a variety of catalytic reactions.

Tri-tert-butylphosphine tetrafluoroborate is widely used as a ligand in transition metal catalysis. Its steric bulk and electron-donating properties enhance the reactivity of metal centers in palladium, platinum, and nickel complexes, promoting key transformations in organic synthesis. For example, it is used in cross-coupling reactions such as Suzuki-Miyaura, Heck, and Sonogashira couplings to form carbon-carbon and carbon-heteroatom bonds. The steric properties of the ligand also facilitate its use in asymmetric catalysis, helping to achieve high enantioselectivities. P(t-Bu)₃•HBF₄ is used to form chiral metal complexes that catalyze enantioselective reactions, which are essential for the production of optically active pharmaceuticals and fine chemicals.

In homogeneous catalysis, tri-tert-butylphosphine tetrafluoroborate is used to improve the efficiency and selectivity of catalytic systems. Its ability to stabilize reaction intermediates and influence reaction pathways makes it valuable in processes such as hydroformylation, hydrogenation, and hydroamination.

Tri-tert-butylphosphine tetrafluoroborate is used in C-H activation reactions, promoting direct functionalization of C-H bonds. This ability to activate inert C-H bonds opens new avenues for the efficient construction of complex organic molecules.

P(t-Bu)₃•HBF₄ can be used as a versatile reagent for ligand substitution reactions, replacing less efficient ligands in metal complexes to improve their catalytic performance. This substitution allows the catalytic system to be fine-tuned to achieve the desired reactivity and selectivity.

The tetrafluoroborate form of tri-tert-butylphosphine provides a stable, non-volatile phosphine source, simplifying its handling and use in sensitive reactions. The salt form is particularly advantageous in reactions that require tight control of moisture and air-sensitive conditions.

In the pharmaceutical industry, tri-tert-butylphosphine tetrafluoroborate is used to synthesize drug candidates and intermediates. Its role in catalysis and C-H activation facilitates the efficient production of complex molecules with therapeutic potential.

The reagent is used in materials science to prepare functional materials and polymers. Its application in polymerization reactions and material modification facilitates the development of advanced materials with tailored properties.

In academic research, P(t-Bu)₃•HBF₄ is used to explore new catalytic methods and reaction mechanisms. Their versatility provides a platform for developing innovative synthetic strategies and expanding the understanding of catalysis.

References

2003. A rapid microwave protocol for Heck vinylation of aryl chlorides under air. Molecular Diversity, 7(2-4).
DOI: 10.1023/b:modi.0000006798.53091.a2

2009. Catalysis with Phosphonium Salts as Ligand Precursors. Science of Synthesis.
URL: https://science-of-synthesis.thieme.com/app/text/?id=SD-042-00431

2011. C-Arylation. Science of Synthesis.
URL: https://science-of-synthesis.thieme.com/app/text/?id=SD-116-00325