Phosphonium‐Based Ionic Liquids Used as Reagents or Catalysts

Abstract

The role and enlarged importance of ionic liquids (ILs) in chemical reactions were already exhaustively demonstrated. The aim of this review is to promote the family of the phosphonium‐based ILs used as reagents and catalysts, which gained increased interest in the last decade. The common and beneficial properties of ILs refer to their negligible vapour pressure, non‐toxicity, reusability, and high thermal stability. Therefore, phosphonium‐based ionic liquids are used successfully as catalysts and reagents in many chemical reactions, and additionally allow the syntheses in mild reaction conditions. Phosphonium ILs have proved their catalytic efficiency in many reactions such as epoxidation of olefins and allylic alcohol, in synthesis of alpha‐aminophosphonates, beta‐ketophosphonates, nitrogen‐containing bisphosphonates, the Michaelis‐Arbuzov reactions, esterification, coupling reaction, aromatic chlorination, dehydrogenation. The major advantage of phosphonium‐based ILs used as catalysts is that they can be reused with only little loss of catalytic activity. Phosphonium ILs revealed their potential as Wittig reagents, halogenation reagents for bromination and bromo‐chlorination reactions with alkenes and alkynes, as monomer and as initiator in frontal polymerization of acrylates. From the literature data, it can be concluded that due to their structure and physical‐chemical properties phosphonium ILs can be tailored function of their purpose.

High‐Performance Porous Ionic Liquids for Low‐Pressure CO2 Capture**

“…The ylide generation from phosphonium-based ionic liquids has been used as Wittig reagents 22 or reaction catalysts. 23 Concerning the acetate anion, it is long known that it is basic enough to abstract the acid S3.…”

New High-Performance Porous Ionic Liquids for Low Pressure CO2 Capture

“…The ylide generation from phosphonium-based ionic liquids has been used as Wittig reagents 22 or reaction catalysts. 23 Concerning the acetate anion, it is long known that it is basic enough to abstract the acid proton from imidazolium cations and lead to a chemical reaction between imidazolium-based acetate ionic liquids and CO 2 . 16,17 Therefore, one could expect that the basicity of the acetate anions can also lead to a carboxylation at the α − carbon atom of tetraalkylphosphonium acetate cations.…”

Phosphonium-Based Porous Ionic Polymer with Hydroxyl Groups: A Bifunctional and Robust Catalyst for Cycloaddition of CO2 into Cyclic Carbonates

“…To gain insight into the structural information of the prepared samples, solid-state 13 C NMR, solid-state 31 P NMR, and XPS analyses were carried out. The solid-state 13 C NMR spectra of PQPBr and PQPBr-2OH in Figure 4a displayed a number of peaks at around 120-150 and 30-70 ppm, corresponding respectively to the carbons of benzene rings and saturated carbon chains. Solid-state 31 P NMR spectra of PQPBr and PQPBr-2OH in Figure 4b showed a main peak with a small peak at around 19.8 ppm and −7.7 ppm, respectively.…”

“…At present, many homogeneous catalytic systems have been developed to promote this conversion. Among them, the homogeneous catalysts based on ionic liquids, such as quaternary ammonium salts [7,8], imidazolium salts [9][10][11], and quaternary phosphonium salts [12][13][14], were demonstrated to be the most efficient. Generally, the homogeneous salts could exhibit high catalytic activity under mild reaction conditions; however, the obvious drawbacks of product separation and catalyst recycling still hamper their large-scale applications.…”