Acylamido-based anion-functionalized ionic liquids for efficient synthesis of poly(isosorbide carbonate)

A catalytic system containing an acylamido-based anion was developed for the synthesis of bio-based polycarbonate by efficient activation of monomers.

Investigating Variation of the Pnicogen Nucleophilic Heteroatom on Ionic Liquid Solvent Effects in Bimolecular Nucleophilic Substitution Processes

A series of nucleophiles containing Group 15 nucleophilic heteroatoms has been used to expand and develop the current understanding of ionic liquid solvent effects on bimolecular nucleophilic substitution processes. It was found that when using arsenic-, antimony- and bismuth-based nucleophiles, rate constant enhancement was observed for all solvent compositions containing ionic liquids. This rate constant enhancement was driven by ionic liquid/transition state interactions, which contrasts with previous studies on earlier Group 15 nucleophiles. This study provides a holistic understanding and augments the predictive framework for the effects of ionic liquids on bimolecular nucleophilic substitution processes, with the potential for these periodic trends to be broadly applied.

Transesterification of Isosorbide with Dimethyl Carbonate Catalyzed by Task-Specific Ionic Liquids

Green synthesis of high-molecular-weight isosorbide-based polycarbonate (PIC) with excellent properties is a tremendous challenge and is profoundly influenced by the precursor. Herein, an ecofriendly catalyst was employed to obtain the more reactive PIC precursor dicarboxymethyl isosorbide (DC) with 99.0 % selectivity through the transesterification reaction of isosorbide with dimethyl carbonate. This is the indispensable stage of a one-pot green synthesis of PIC, playing a critical role in giving an insight into the polymerization mechanism of polymer synthesis through the melt transesterification reaction. To this end, a series of 4-substituted phenolate ionic liquids (ILs) were developed as a new type of high-efficiency catalyst for this reaction. These homogeneous ILs exhibited outstanding catalytic performances. The DC selectivity increased gradually with decreasing IL basicity; among the ILs studied, trihexyl(tetradecyl)phosphonium 4-iodophenolate ([P₆₆₆₁₄ ][4-I-Phen]) showed the highest catalytic activity. Additionally, according to the experimental results and DFT calculations, a plausible nucleophilic activation mechanism was proposed, which confirmed that the reaction is activated through the formation of H-bonds and electrostatic interactions with the IL catalyst. This strategy of tunable basicity and structure of anions in ILs affords an opportunity to develop other ILs for the transesterification reaction, thereby conveniently providing a variety of polymers through a green synthetic pathway.

New dimensions in salt-solvent mixtures: a 4th evolution of ionic liquids

In the field of ionic liquids (ILs) it has long been of fundamental interest to examine the transition from salt-in-solvent behaviour to pure liquid-salt behaviour, in terms of structures and properties. At the same time, a variety of applications have beneficially employed IL-solvent mixtures as media that offer an optimal set of properties. Their properties in many cases can be other than as expected on the basis of simple mixing concepts. Instead, they can reflect the distinct structural and interaction changes that occur as the mixture passes through the various stages from pure coulombic medium, to "plasticised" coulombic medium, into a meso-region where distinct molecular and ionic domains can co-exist. Such domains can persist to quite a high dilution into the salt-in-solvent regime and their presence manifests itself in a number of important synergistic interaction effects in diverse areas such as membrane transport and corrosion protection. Similarly, the use of ionic liquids in synthetic processes where there is a significant volume fraction of molecular species present can produce a variety of distinct and unexpected effects. The range of these salt-solvent mixtures is considerably broader than just those based on ionic liquids, since there is only minor value in the pure salt being a liquid at the outset. In other words, the extensive families of organic and metal salts become candidates for study and use. Our perspective then is of an evolution of ionic liquids into a broader field of fundamental phenomena and applications. This can draw on an even larger family of tuneable salts that exhibit an exciting combination of properties when mixed with molecular liquids.

Is it possible to control kinetic rates of radical polymerisation in ionic liquids?

Experimental studies have noted the often surprising and unpredictable effect of ionic liquids as solvents on reaction kinetics for radical polymerisation. We theoretically investigate the energetic and structural effects of ionic liquids, both protic and aprotic, on radical stability, presenting stabilisation of the radical by the ionic liquid by up to -78.0 kJ mol-1. Kinetic data relating to propagating systems for several industrially viable monomers indicate that propagation rates can be increased or decreased (by up to 6 orders of magnitude) depending on the monomer and ionic liquid combination. The interplay of activation entropy and activation enthalpy, much of which depends on hydrogen bonding between the solvent and reactants, play a crucial role in controlling reaction kinetics. It is concluded that the use of cheaper protic ionic liquids as solvents may be viable for improved kinetic control over radical reactions.

The effect of varying the anion of an ionic liquid on the solvent effects on a nucleophilic aromatic substitution reaction

Variety of ionic liquids with different anions used as solvents for a nucleophilic aromatic substitution reaction.

Rationalising the effects of ionic liquids on a nucleophilic aromatic substitution reaction

The nucleophilic aromatic substitution reaction between 1-fluoro-2,4-dinitrobenzene and ethanol was examined in a series of ionic liquids across a range of mole fractions.