Reaction dynamics, ionic liquids

Shim, Y. Kim, H. (2009). Adiabatic electron transfer in a room-temperature ionic liquid Reaction dynamics and kinetics, /. Phys. Chem. B 113(39) 12964-12972. 

Sethi, A. R., Welton, T., Dynamic supramolecular chemistry The role of hydrogen bonding in controlling the selectivity of Diels-Alder reactions in room-temperature ionic liquids, Ionic Liquids, 2002, 818, 41-246. 

In the last few years numerous reports have been published in the field of microwave-promoted aryl halide cyanation, utilizing nickel [71], palladium [72,73] and copper [74,75] catalysis. Even water [75] and ionic liquids [76] have proven useful as solvents in these processes. Srivastava and Collibee have exemplified a swift and dynamic procedure using polymer-supported triphenyl phosphine to enable easy subsequent removal through filtration [72]. As shown in Scheme 19, both bromides and iodides could be activated using palladium catalysis in DMF. Even without optimization of the individual reaction times, the overall process time involving simple filtration and extraction for compound isolation appears to be short. 

In order to optimize and/or improve the behaviour of bioprocesses in ionic liquids/supercritical carbon dioxide biphasic systems, a better understanding of the chemical reaction and mass-transfer phenomena in these biphasic systans is required. In this context, de los Rfos et al. [38] analysed the chemical reaction and the mass-transfer phenomena in the synthesis of bntyl propionate from vinyl propionate and 1-butanol catalysed by CaLB immobilized on dynamic monbranes at... 

With the intensive development of ultrafast spectroscopic methods, reaction dynamics can be investigated at the subpicosecond time scale. Femtosecond spectroscopy of liquids and solutions allows the study of sol-vent-cage effects on elementary charge-transfer processes. Recent work on ultrafast electron-transfer channels in aqueous ionic solutions is presented (electron-atom or electron-ion radical pairs, early geminate recombination, and concerted electron-proton transfer) and discussed in the framework of quantum theories on nonequilibrium electronic states. These advances permit us to understand how the statistical density fluctuations of a molecular solvent can assist or impede elementary electron-transfer processes in liquids and solutions. 

In 2002 we predicted that non-synthetic applications would have a great chance to be among the first technical ionic liquid applications. This assumption has held true as Chapter 9 clearly proves. Non-synthetic applications are particularly attractive due to their often much shorter development times. Usually, the improvement over existing technology is only based on one or very few specific properties of the ionic liquid, whereas, for most synthetic applications a complex mixture of physicochemical properties in dynamic mixtures has to be considered. This point is well illustrated by the fact that all liquid-liquid biphasic catalysis involves both a reaction and an extraction step. Hence, the ionic liquid catalyst solution has to ftilfil at the same time aU of the requirements to work as a superior reaction medium as well as its role as a suitable extraction medium. The result is a significantly more complex set of material requirements which prolongs the specific ionic liquid development and testing times. 

Of course, all these concentration effects are highly dependent on the nature of the substrate dissolved in the ionic liquid as well as on the nature of the ionic liquid s cation and anion. Given the enormous possibility to vary these, and the highly dynamic character of reacting systems, it becomes clear that a detailed understanding of the role of the ionic liquid in reaction mixtures is still far from complete. 

In fact it is hard to measure the intrinsic anodic behavior of LLMOj, cathode materials in standard electrolyte solutions because at too high potentials the anodic reactions of solution species may dominate the potentio-dynamic response. However, ionic liquid solutions based on quaternary ammonium cations, TFSI anion, and LiTFSI salt demonstrate very high anodic stability. The passivation of Al current collector is excellent in these solutions. So, the anodic stability of Al... 

The last section was devoted to a range of real-world applications treated with ab initio molecular dynamics simulations. Results of gas to liquid phase transition simulations, structural and dynamical properties of liquids such as common solvents as well as the emerging neoteric media of ionic liquids were presented. After a short discussion of chemical reactions concerning homogeneous catalysis, we presented an overview of electrochemical reactions and related processes. 

Copper(I)-catalyzed tandem reaction of isothiocyanates and iodophenols in ionic liquids produced 95 (13JOM(723)137) iodine-mediated electrophilic cychzation of osmabenzene resulted in the isolation and characterization the osmabenzene-fused oxathiole 96 (13AGE9251) and nickel chloride-catalyzed reaaion of aromatic aldehydes with 2-mercaptoethanol produced 97 only as a minor product together with the bis(2-hydroxyethyl)dithioac-etals (13TL5839). Lamivudine 98 and its enantiomer 99 have been efficiently asymmetrically synthesized via enzymatic dynamic kinetic resolution (13CC10376). The deprotection of 1,3-oxathiolanes 100 promoted by a range of bases has been examined (13TL2217). 

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