Pyrrolidinium cations

Common ILs include ammonium, phosphonium, sulfonium, guanidinium, pyridinium, imidazolium, and pyrrolidinium cations. However, use of nomenclature vary among researchers. It is prefered to abbreviate throughout this book as [C C ,CJm], [C py], and [C C ,pyr] for the alkylimidazolium, pyridinium, and pyrrolidinium cations, respectively, where Im stands for imidazolium, py for pyridinium, and pyr for pyrrolidinium. The number of carbons in the N-alkyl chains are expressed by n, m, and z. 

Since anions less polarizable than the perfluorinated species represented in Figure 2.6 cannot be made, it would seem that if fluorinated species are to be avoided for economic reasons, the number of anions that can be used in acceptable ionic liquids is rather limited. Nitrates, thiocyanates, nitrites, formates, dicyanamides, chlorosulfonates, and methanesulfonates would seem to be acceptable. Dicyanamides have been shown to have high fluidities with imidazolium and pyrrolidinium cations [28, 43]. 

Figures 24.1 and 24.2 present the thermal analysis traces for a range of typical plastic crystal materials based on the pyrrolidinium cation. The highest temperature phase is denoted as phase 1, with subsequent lower temperature phases denoted as phases II, III, and so on. It can be seen that the nature of the anion plays a significant role in the thermal behavior of these compounds. For example, PnTFSA has a barely detectable solid-solid transition at 20°C, followed by a melt at above...

Song Y, Liu L, Zhu X F, et al. Physicochemical properties of ionic liquids based on imidazolium/pyrrolidinium cations and maleate/ phthalate anions. Solid State Ionics. 2008. 179, 516-521. 

An important property of an ionic liquid in terms of its applications in biomass processing is its thermal stability, which is usually measured by thermogravimetric analysis. Nucleophilicity of the anion has been found to have an effect on the thermal stability of many ionic liquids due the role of the anion in the degradation of the cation [76], Quaternary ammonium, imidazolium, phosphonium and pyrrolidinium cations degrade at lower temperatures in the presence of highly nucleophilic anions such as halides due to Hoffman elimination and reverse Menschutkin reactions [76-79],... 

An alternative approach to that of Ge et al. [110] was adopted by Gardas and Coutinho [117]. In this study 2,396 data points for 19 ILs consisting of combinations of imidazolium, pyridinium and pyrrolidinium cations with a range of anions including [PF6], [BF4] , [NTf2] , Br, and [OTf]" anions, over a wide temperature range from 196.36 to 663.10 K was modeled using the method proposed by... 

In a subsequent study [20], the authors attached pendant calamitic mesogenic cores to the pyrrolidinium cation, 14,15, and 16. In some cases, a low-ordered SmA... 

Henderson, W.A. Passerini, S., Phase Behavior of Ionic Liquid-LiX Mixtures Pyrrolidinium Cations and XFSI-Anions, Chem. Mater, 2004,16,2881-2885. 

In another quite original contribution, Mele and co-workers showed evidence of fluorous domain segregation in ionic liquids, obtained in ionic liquids with pyrrolidinium cations and perfluorinated anions of the family of fluorosulfonylamides [74]. 

W.A., Phase behavior of ionic liquid-LiX mixtures Pyrrolidinium cations and TFSI anions -linking structure to transport properties, Chem. Mater. 23 (19), 4331 337 (2011). 

Harmand J., Rogalski M., Sindt M. Mieloszynski J.L. (2009). Preparation of molten salt-type (meth)acrylic monomers and their application as catalysts in the synthesis of benzyl phenyl sulfide an alternative to the usual toxic sulfides synthesis. Environ. Ghem. Letters, vol. 7, n°3, pp.255-260, (September 2009), ISSN 1610-3653 Henderson W.A. Passerini S. (2004). Phase Behavior of Ionic Liquid-LiX Mixtures Pyrrolidinium Cations and TFSL Anions, Ghem. Mater., vol.l6, n°15, pp.2881-2885. ISSN 0897-4756... 

Two other parameters influence the electrolyte behavior in the EDLC system the van der Waals volume of ions, which must adapt itself to the material porosity, and their polarizability (Fig. 7.22). These two parameters are correlated, e.g., the volume of the [NHEt(i-Pr)2] cation (207.37 A ) is twice that of the pyrrolidinium cation (106.01 A ), but at the same time, [NHEt(i-Pr)2]" displays higher polarizability (Fig. 7.22), which allows better distortion in order to adapt its size to the carbon pore size [143]. Thus, [NHEt(i-Pr)2]" counterbalances its larger volume by its higher polarizability. This believable hypothesis linking reduction stability limit to the geometry and the volume of cations could explain the different behavior observed in Fig. 7.21. 

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