Allyltriphenylphosphonium bromide is a versatile organophosphorus compound widely used in modern organic synthesis. With the molecular formula C₂₁H₂₀PBr and a CAS number 1560-54-9, it plays a vital role as a reagent in constructing complex organic molecules, particularly in carbon–carbon bond formation.
IUPAC Name: Triphenyl(prop-2-en-1-yl)phosphanium bromide
Molecular Formula: C₂₁H₂₀PBr
Molar Mass: 399.27 g/mol
Appearance: White to off-white crystalline powder
Solubility: Soluble in polar organic solvents such as ethanol, methanol, and acetonitrile.
One of the most prominent uses of allyltriphenylphosphonium bromide is in Wittig olefination. In the presence of a strong base, such as sodium hydride or potassium tert-butoxide, it generates the corresponding ylide, which reacts with aldehydes or ketones to produce alkenes.
Example: Conversion of carbonyl compounds to allyl-substituted alkenes, useful in synthesizing natural products and bioactive molecules.
The allyl group in this compound allows for C3 chain extension in target molecules. This is particularly useful in the synthesis of advanced intermediates for pharmaceuticals and agrochemicals.
The allyl moiety can participate in [3+2] cycloaddition and Diels–Alder type reactions when transformed into appropriate intermediates, enabling the creation of cyclic structures with high stereoselectivity.
In certain catalytic systems, allyltriphenylphosphonium bromide can serve as an allyl donor in transition-metal-catalyzed cross-coupling reactions, leading to valuable allylated products.
Its role in introducing allyl groups into frameworks makes it valuable in the preparation of polymerizable monomers, ligands, and surface modifiers for advanced materials science applications.
High Selectivity: Often yields the desired olefin with good stereochemical control.
Stable and Easy to Handle: Unlike many reactive intermediates, it can be stored without special conditions.
Versatile Reactivity: Suitable for use in both small-scale laboratory synthesis and industrial processes.
Store in a cool, dry place away from moisture.
Use gloves and eye protection during handling.
Avoid prolonged exposure to air to prevent degradation.
Allyltriphenylphosphonium bromide stands out as a valuable reagent for synthetic chemists, offering a clean and efficient route to allylated compounds and diverse carbon–carbon bond-forming transformations. Whether for academic research or industrial-scale synthesis, its versatility and reliability make it a staple in organic chemistry laboratories.
