Tetraphenylphosphonium bromide
[CAS# 2751-90-8]

Identification

• Classification: Organic raw materials >> Organic phosphine compound
• Name: Tetraphenylphosphonium bromide
• Molecular Formula: C₂₄H₂₀BrP
• Molecular Weight: 419.30
• CAS Registry Number: 2751-90-8
• EC Number: 220-393-4
• SMILES: C1=CC=C(C=C1)[P+](C2=CC=CC=C2)(C3=CC=CC=C3)C4=CC=CC=C4.[Br-]

Properties

• Melting point: 295-300 °C (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

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

Discovery and Applications

Tetraphenylphosphonium bromide (C24H20PB) is a quaternary ammonium salt composed of a phosphonium cation, where a phosphorus atom is bonded to four phenyl groups (C6H5), and a bromide anion (Br−). It is commonly used in organic synthesis and as a phase-transfer catalyst.

The compound is synthesized by reacting triphenylphosphine with an alkyl or aryl bromide. In its solid form, it appears as a white crystalline powder, which is soluble in organic solvents such as acetone and chloroform, but insoluble in water.

Tetraphenylphosphonium bromide is primarily used as a phase-transfer catalyst, a role that enables the transfer of anionic species from an aqueous phase to an organic phase in reactions. This property is particularly useful in reactions that require the presence of ionic intermediates or reactants that would otherwise be insoluble in organic solvents. By facilitating the solubilization of ions into organic solvents, it enhances the rate and efficiency of several chemical reactions, such as nucleophilic substitution, alkylation, and esterification.

In addition to its catalytic applications, tetraphenylphosphonium bromide has been employed in the synthesis of a variety of organic compounds, particularly in the context of organic synthesis where the transformation of substrates in non-aqueous media is necessary. It has also been used as a precursor in the preparation of other phosphonium salts, which find applications in different fields, including materials science and medicinal chemistry.

References

2022. Tetraphenylphosphonium Chloride-Enhanced Ionization Coupled to Orbitrap Mass Spectrometry for Sensitive and Non-targeted Screening of Polyhalogenated Alkyl Compounds from Limited Serum. Analytical Chemistry, 94(40).
DOI: 10.1021/acs.analchem.2c02158

2021. Nongenotoxic ABCB1 activator tetraphenylphosphonium can contribute to doxorubicin resistance in MX-1 breast cancer cell line. Scientific Reports, 11(1).
DOI: 10.1038/s41598-021-86120-6

2022. High-pH structure of EmrE reveals the mechanism of proton-coupled substrate transport. Nature Communications, 13(1).
DOI: 10.1038/s41467-022-28556-6