Benzyltriphenylphosphonium bromide
[CAS# 1449-46-3]

Identification

• Classification: Organic raw materials >> Organic phosphine compound
• Name: Benzyltriphenylphosphonium bromide
• Synonyms: Bromo(benzyl)triphenylphosphorane
• Molecular Formula: C₂₅H₂₂P.Br
• Molecular Weight: 433.33
• CAS Registry Number: 1449-46-3
• EC Number: 215-908-4
• SMILES: C1=CC=C(C=C1)C[P+](C2=CC=CC=C2)(C3=CC=CC=C3)C4=CC=CC=C4.[Br-]

Properties

• Melting point: 295-298 °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
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovery and Applications

Benzyltriphenylphosphonium bromide (C6H5CH2P(C6H5)3Br) is a quaternary phosphonium salt composed of a benzyl group attached to a triphenylphosphonium cation, along with a bromide anion. This compound is typically synthesized through the reaction of triphenylphosphine with benzyl bromide, resulting in the formation of the desired phosphonium salt.

Benzyltriphenylphosphonium bromide is widely used in organic synthesis, primarily as a reagent in various chemical transformations. It is known for its role in the Wittig reaction, which is a key method for synthesizing alkenes. In this reaction, benzyltriphenylphosphonium bromide reacts with an aldehyde or ketone to form an alkene through the formation of a phosphonium ylide intermediate. This reaction is central to the creation of a wide variety of carbon-carbon double bonds, which are fundamental in many synthetic routes for pharmaceuticals, polymers, and other organic compounds.

In addition to its role in the Wittig reaction, benzyltriphenylphosphonium bromide has applications in other synthetic processes involving the generation of phosphonium ylides. It is used in reactions where the phosphonium group facilitates the transfer of the benzyl group, often leading to the formation of substituted alkenes or other important functional groups in organic synthesis.

Benzyltriphenylphosphonium bromide is also valuable in the synthesis of other phosphonium salts, which find applications in a range of chemical processes. The versatility of phosphonium compounds makes them useful in various catalytic and stoichiometric roles, where they often act as electrophiles or catalysts in nucleophilic substitution reactions.

In summary, benzyltriphenylphosphonium bromide is a well-established compound in organic chemistry, primarily utilized in the Wittig reaction for the synthesis of alkenes. Its role as a phosphonium ylide precursor makes it a key reagent in the construction of carbon-carbon bonds and in the synthesis of various organic molecules.

References

2017. Ionic salt (4-ethoxybenzyl)-triphenylphosphonium bromide as a green corrosion inhibitor on mild steel in acidic medium: experimental and theoretical evaluation. RSC Advances, 7(51).
DOI: 10.1039/C6RA27526E

1980. Effects of phosphonium compounds on Schistosoma mansoni. Journal of Medicinal Chemistry, 23(8).
DOI: 10.1021/jm00182a010

1979. A new chemical series active against African trypanosomes: benzyltriphenylphosphonium salts. Journal of Medicinal Chemistry, 22(4).
DOI: 10.1021/jm00190a019