Solvents for sustainable chemical processes

Abstract

This review highlights solvent systems that were designed to simultaneously address reaction, separation and recycling challenges.

Dissolution of Trihexyltetradecylphosphonium Chloride in Supercritical CO2

“…Supercritical fluids, carbon dioxide (scCO 2 ) in particular, have been recognized as alternative, green solvents for use in industrial processes [1,23]. The interest stems from the ability to tune the solvent characteristics by simply adjusting the system pressure, and therefore, the fluid density [24].…”

“…For almost two decades, many groups have studied CO2 interactions with ILs, which has led to IL applications such as CO2 capture [26,27], catalyst recycling [23,28] and nanomaterial processing [1]. Much of the work to date, both experimental and theoretical, has focused nearly exclusively on various 1-alkyl-3-methyl imidazolium cations in combination with a variety of anions, where the cation alkyl chains used have been typically from C2 to C6 [1,23,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. This body of literature can be summarized by two main goals: (1) the measurement of the phase behavior of CO2 dissolved in ILs; and (2) the quantitation of CO2 solubility in a bulk phase IL.…”

“…RTILs are also designer solvents in the sense that a wide variety of cations and anions can be combined to tailor ILs for task-specific processes or reactions [1,2]. RTILs have unique characteristics, such as low volatility, non-flammability and water miscibility, that make them candidates for use in many applications, and has given rise to their use as cosolvents [3][4][5][6] in numerous applications [1,[3][4][5][6][7][8][9][10][11][12][13] that include electrochemistry [14][15][16], organic synthesis [17,18], gas separation/SLM's [19,20] and catalysis [17,21]. The inherent polar and nonpolar nanodomains that form in ILs allow them to readily solvate polar and non-polar solutes, and this has given rise to a significant increase in their study over the last decade [8,14,15,17,[19][20][21][22].…”

Ionic Liquids: Synthesis and Applications in Catalysis

“…It is recognized that employing the use of nonconventional solvents as alternatives for environmentally unfriendly traditional solvents can reduce waste solvent production and hence reduce the negative impact on environment to a great extent [2]. The most prevalent of these new solvent systems includes, but not exclusively, water, supercritical fluids (like supercritical CO 2 ), ionic liquids, solventless processes, and fluorous techniques [3].…”

“…[ 3 ] is a simple salt whereas mixtures of aluminum(III) chloride and 1,3-dialkylimidazolium chlorides (a binary ionic liquid system) contain several different ionic species, and their melting point and properties depend upon the mole fractions of aluminum(III) chloride and 1,3-dialkylimidazolium chloride present.…”