Keith E. Gutowski
Bio: Keith E. Gutowski is an academic researcher from University of Alabama. The author has contributed to research in topics: Ionic liquid & Density functional theory. The author has an hindex of 13, co-authored 18 publications receiving 2351 citations. Previous affiliations of Keith E. Gutowski include Queen's University Belfast & Environmental Molecular Sciences Laboratory.
TL;DR: Hydrophilic ionic liquids can be salted-out and concentrated from aqueous solution upon addition of kosmotropic salts forming aqueously biphasic systems as illustrated by the phase behavior of mixtures of 1-butyl-3-methylimidazolium chloride and K3PO4.
Abstract: Hydrophilic ionic liquids can be salted-out and concentrated from aqueous solution upon addition of kosmotropic salts forming aqueous biphasic systems as illustrated by the phase behavior of mixtures of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and K3PO4.
TL;DR: In this article, phase diagrams for imidazolium-, pyridium-, and quaternary ammonium-and phosphonium-based chloride salts (all chaotropic salts) were described, and the Gibbs free energy of methylene transfer (GCH2) was also determined for 1-butyl-3methylimidazolate chloride ([C4mim]Cl)/K3PO4, K2HPO4, and K2CO3 ABS.
Abstract: A study of salt–salt aqueous biphasic systems (ABS) was conducted to increase our understanding of solutions of kosmotropic vs. chaotropic salts, especially since most ionic liquids (ILs) fall within the latter class. The salting-out strength of the kosmotropic salts follows the well established Hofmeister series, as observed in polymer–salt ABS, and can be directly related to the ions' Gibbs free energies of hydration (ΔGhyd). Most currently studied ILs are designed to have chaotropic cations and are thus salted-out by kosmotropic salts. Here, we describe the phase diagrams for imidazolium-, pyridium-, and quaternary ammonium- and phosphonium-based chloride salts (all chaotropic salts) salted-out by K3PO4, K2HPO4, K2CO3, KOH, and (NH4)2SO4 (all kosmotropic salts). The Gibbs free energy of methylene transfer (ΔGCH2) was also determined for 1-butyl-3-methylimidazolium chloride ([C4mim]Cl)/K3PO4, K2HPO4, and K2CO3 ABS. The latter results are in the range of an ethanol–water to a chloroform–water system, and can be controlled predominately by the system composition.
TL;DR: Ionic liquids have found widespread use in biochemical, electrochemical, catalytic, and synthetic applications, and have recently been applied to important areas of f-element chemistry as discussed by the authors.
Abstract: Ionic liquids (ILs) have found widespread use in biochemical, electrochemical, catalytic, and synthetic applications, and have recently been applied to important areas of f-element chemistry. This review highlights the use of ILs in separation schemes for the sequestration of actinide ions (including lanthanides, where appropriate, as stand-ins for actinide ions), the solid-state chemistry of actinide complexes containing imidazolium cations, and the spectroscopy and electrochemistry of actinide cationic and anionic species. Particular emphasis is placed on the coordination environments that are present under a variety of conditions, such as acidic and basic tetrachloroaluminate melts. Also, this review touches on the recent use of computer simulations to elucidate the microscopic interactions that result in the preferential solvation of actinide ions in ILs.
TL;DR: R Rearrangement reactions based on an intramolecular isomerization leading to a redistribution of water in the two shells provide good values in comparison to experiment with values of Delta G(exchange) from -2.2 to -0.5 kcal/mol so the inclusion of a second hydration sphere accounts for most solvation effects.
Abstract: The structures and vibrational frequencies of UO2(H2O)42+ and UO2(H2O)52+ have been calculated using density functional theory and are in reasonable agreement with experiment. The energies of various reactions were calculated at the density functional theory (DFT) and MP2 levels; the latter provides the best results. Self-consistent reaction field calculations in the PCM and SCIPCM approximations predicted the free energy of the water exchange reaction, UO2(H2O)42+ + H2O ↔ UO2(H2O)52+. The calculated free energies of reaction are very sensitive to the choice of radii (O and H) and isodensity values in the PCM and SCIPCM models, respectively. Results consistent with the experimental HEXS value of −1.19 ± 0.42 kcal/mol (within 1−3 kcal/mol) are obtained with small cavities. The structures and vibrational frequencies of the clusters with second solvation shell waters: UO2(H2O)4(H2O)82+, UO2(H2O)4(H2O)102+, UO2(H2O)4(H2O)112+, UO2(H2O)5(H2O)72+, and UO2(H2O)5(H2O)102+, were calculated and are in better agree...
TL;DR: A computational approach to predict the thermodynamics for forming a variety of imidazolium-based salts and ionic liquids from typical starting materials is described and triflate reagents appear to be the best overall choice as protonating and methylating agents.
Abstract: A computational approach to predict the thermodynamics for forming a variety of imidazolium-based salts and ionic liquids from typical starting materials is described. The gas-phase proton and methyl cation acidities of several protonating and methylating agents, as well as the proton and methyl cation affinities of many important methyl-, nitro-, and cyano-substituted imidazoles, have been calculated reliably by using the computationally feasible DFT (B3LYP) and MP2 (extrapolated to the complete basis set limit) methods. These accurately calculated proton and methyl cation affinities of neutrals and anions are used in conjunction with an empirical approach based on molecular volumes to estimate the lattice enthalpies and entropies of ionic liquids, organic solids, and organic liquids. These quantities were used to construct a thermodynamic cycle for salt formation to reliably predict the ability to synthesize a variety of salts including ones with potentially high energetic densities. An adjustment of th...
TL;DR: Rogers and Seddon as discussed by the authors reviewed recent progress on developing new ionic liquid solvents for use in chemical synthesis, catalysis, fuel cells, and other applications.
Abstract: Ionic liquids are composed entirely of ions. Because of the wide range of possible binary and ternary ionic liquids, they offer a potentially wide range of solvent properties. In their Perspective, Rogers and Seddon review recent progress on developing new ionic liquid solvents for use in chemical synthesis, catalysis, fuel cells, and other applications. Ionic liquids are considered advantageous not only because of their versatility but also for their "green" credentials, although it is important to remember that not all ionic liquids are environmentally benign. One industrial process has been reported, and others may not be far behind. The authors conclude that in the next decade, ionic liquids are likely to replace conventional solvents in many applications.
TL;DR: The Gaussian-4 theory (G4 theory) for the calculation of energies of compounds containing first- (Li-F), second- (Na-Cl), and third-row main group (K, Ca, and Ga-Kr) atoms is presented and a significant improvement is found for 79 nonhydrogen systems.
Abstract: The Gaussian-4 theory (G4 theory) for the calculation of energies of compounds containing first- (Li–F), second- (Na–Cl), and third-row main group (K, Ca, and Ga–Kr) atoms is presented. This theoretical procedure is the fourth in the Gaussian-n series of quantum chemical methods based on a sequence of single point energy calculations. The G4 theory modifies the Gaussian-3 (G3) theory in five ways. First, an extrapolation procedure is used to obtain the Hartree-Fock limit for inclusion in the total energy calculation. Second, the d-polarization sets are increased to 3d on the first-row atoms and to 4d on the second-row atoms, with reoptimization of the exponents for the latter. Third, the QCISD(T) method is replaced by the CCSD(T) method for the highest level of correlation treatment. Fourth, optimized geometries and zero-point energies are obtained with the B3LYP density functional. Fifth, two new higher level corrections are added to account for deficiencies in the energy calculations. The new method is ...
TL;DR: In this article, the dissolution of cellulose with ionic liquids and its application were reviewed, where cellulose can be easily regenerated from its ionic liquid solutions by addition of water, ethanol or acetone.
Abstract: Dissolution of cellulose with ionic liquids allows the comprehensive utilization of cellulose by combining two major green chemistry principles: using environmentally preferable solvents and bio-renewable feed-stocks. In this paper, the dissolution of cellulose with ionic liquids and its application were reviewed. Cellulose can be dissolved, without derivation, in some hydrophilic ionic liquids, such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-allyl-3-methylimidazolium chloride (AMIMCl). Microwave heating significantly accelerates the dissolution process. Cellulose can be easily regenerated from its ionic liquid solutions by addition of water, ethanol or acetone. After its regeneration, the ionic liquids can be recovered and reused. Fractionation of lignocellulosic materials and preparation of cellulose derivatives and composites are two of its typical applications. Although some basic studies, such as economical syntheses of ionic liquids and studies of ionic liquid toxicology, are still much needed, commercialization of these processes has made great progress in recent years.