Alkylphosphonium ion

The cations in ionic liquids are generally bulky monovalent organics. The typical cations of ionic liquids, not including the familiar alkylammonium and alkylphosphonium ions, are shown in Fig. 2. It is primarily the cations, which account for the low melting points of ionic liquids. The dialkylimidazolium ions, such as 1-butyl-3-methyl imidazolium [BMIM], have been widely investigated because low-melting ionic liquids can be made readily from such cations and because of their thermal and chemical stability. 

Fig. 2. Typical cations used in ionic liquids, excluding alkylammonium and alkylphosphonium ions.

The cations of the ionic liquid include organic and inorganic cations. Examples of cations include dialkylimidazolium ion, tetra-alkylphosphonium ion, etc. and these cations can be associated with a number of different anions (Fig. 1). The anion includes organic and inorganic anions such as PFg, CF3S03, CF3C00, etc. and Lewis acids such as AlCU", GaC, etc. 

In order to render the silicate layer surface more organophilic and thus more compatible with the polymer matrix, these intercalated alkaline cations can be exchanged with cationic surfactants such as alkylammonium or alkylphosphonium ions" . ... 

Room temperature ionic liquids arc currently receiving considerable attention as environmentally friendly alternatives to conventional organic solvents in a variety of contexts.144 The ionic liquids have this reputation because of their high stability, inertness and, most importantly, extremely low vapor pressures. Because they are ionic and non-conducting they also possess other unique properties that can influence the yield and outcome of organic transformations. Polymerization in ionic liquids has been reviewed by Kubisa.145 Commonly used ionic liquids are tetra-alkylammonium, tetra-alkylphosphonium, 3-alkyl-l-methylimidazolium (16) or alkyl pyridinium salts (17). Counter-ions are typically PF6 and BF4 though many others are known. 

Phosphonium ions exchange with acidic deuterium sources to form P—D bond-containing products. Alkylphosphoniums react with D O as ... 

In the absence of the carbonyl or similar stabilizing group, the onium salts are much less acidic. Strong bases such as amide ion or the anion of DMSO are required to deprotonate alkylphosphonium salts ... 

Layered silicates have positive ions present on the surface which makes them hydrophilic and therefore incompatible with many polymers as they are generally hydrophobic [22]. To make bio-nanocomposites, it is necessary to modify the layered silicates by replacing the interlayer cations with cations bearing long alkyl chains, such as alkylphosphonium or alkylammonium [23]. Alkyl ammonium cations are employed to lower the surface energy and enhance the wetting characteristics with the polymer [24]. By incorporating polymers or monomers into the interlayer, this can lead to the formation of a bio-nanocomposite. Different structures can exist for polymer/clay bio-nanocomposites and they are as follows (see Fig. 2) ... 

Knowledge of ion distribution equilibria at liquid interfaces is of primary importance to various fields of science and technology, not only to the investigation of-reactions of ion and electron transfer but also to the theory and practice of various processes examined in research and industrial laboratories. To begin with, one should mention bioelectrochemistry, liquid-liquid extraction, ion-selective electrodes, emulsification and some reactions of interest to organic chemistry, e.g. interfacial processes catalyzed in the presence of tetraalkylammonium or tetra-alkylphosphonium salts. It should be noted here that a water-immiscible organic phase forms an interfacial liquid membrane such liquid membranes can be appHed for the purpose of selective separation of ions [16]. A potential difference between two aqueous solutions, separated from each other by a Kquid or other membrane, is defined as the membrane potential. 

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