Molecular design of crown ethers. 1. Effects of methylene chain length: 15- to 17-crown-5 and 18- to 22-crown-6
TL;DR: Synthese des ethers crown and evaluation de leur aptitude a former des cations par extraction par solvant des picrates alcalins aqueux. La stabilite des complexes cation-ether crown est gouvernee par la variation d'enthalpie
Abstract: Synthese des ethers crown et evaluation de leur aptitude a former des cations par extraction par solvant des picrates alcalins aqueux. La stabilite des complexes cation-ether crown est gouvernee par la variation d'enthalpie
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TL;DR: This critical review systematically survey the physicochemical properties of the collective library of ether- and alcohol-functionalized ILs, highlighting the impact of ionic structure on features such as viscosity, phase behavior/transitions, density, thermostability, electrochemical properties, and polarity.
Abstract: In recent years, the designer nature of ionic liquids (ILs) has driven their exploration and exploitation in countless fields among the physical and chemical sciences. A fair measure of the tremendous attention placed on these fluids has been attributed to their inherent designer nature. And yet, there are relatively few examples of reviews that emphasize this vital aspect in an exhaustive or meaningful way. In this critical review, we systematically survey the physicochemical properties of the collective library of ether- and alcohol-functionalized ILs, highlighting the impact of ionic structure on features such as viscosity, phase behavior/transitions, density, thermostability, electrochemical properties, and polarity (e.g. hydrophilicity, hydrogen bonding capability). In the latter portions of this review, we emphasize the attractive applications of these functionalized ILs across a range of disciplines, including their use as electrolytes or functional fluids for electrochemistry, extractions, biphasic systems, gas separations, carbon capture, carbohydrate dissolution (particularly, the (ligno)celluloses), polymer chemistry, antimicrobial and antielectrostatic agents, organic synthesis, biomolecular stabilization and activation, and nanoscience. Finally, this review discusses anion-functionalized ILs, including sulfur- and oxygen-functionalized analogs, as well as choline-based deep eutectic solvents (DESs), an emerging class of fluids which can be sensibly categorized as semi-molecular cousins to the IL. Finally, the toxicity and biodegradability of ether- and alcohol-functionalized ILs are discussed and cautiously evaluated in light of recent reports. By carefully summarizing literature examples on the properties and applications of oxy-functional designer ILs up till now, it is our intent that this review offers a barometer for gauging future advances in the field as well as a trigger to spur further contemplation of these seemingly inexhaustible and—relative to their potential—virtually untouched fluids. It is abundantly clear that these remarkable fluidic materials are here to stay, just as certain design rules are slowly beginning to emerge. However, in fairness, serendipity also still plays an undeniable role, highlighting the need for both expanded in silico studies and a beacon to attract bright, young researchers to the field (406 references).
489 citations
TL;DR: In this article, the ideal solubility selectivities of room-temperature ionic liquids (RTILs) with one, two, or three oligo-ethylene glycol substituents were determined using a pressure decay technique.
Abstract: Novel imidazolium-based room-temperature ionic liquids (RTILs) with one, two, or three oligo(ethylene glycol) substituents were synthesized. Solubilities and ideal solubility selectivities of CO2, N2, and CH4 at low pressure (1 atm) in these RTILs were determined using a pressure decay technique. Comparison to corresponding alkyl analogues of these RTILs reveals similar levels of CO2 solubility but lower solubilities of N2 and CH4. As a consequence, RTILs with oligo(ethylene glycol) substituents were observed to have 30−75% higher ideal solubility selectivities for CO2/N2 and CO2/CH4.
224 citations
TL;DR: The 25,27-dialkoxycalix-[4]arenecrown-5 conformers 8, 10, and 11 have been synthesized and studied in this article.
Abstract: New 25,27-dialkoxycalix-[4]arenecrown-5 conformers 8, 10, and 11 have been synthesized and studied. The compounds 8a and 8b, fixed in 1,3-alternate structure, have been obtained in 57 and 40% yield, respectively, by reaction of the corresponding 25,27-dialkoxycalix[4]arenes 7a-b with tetraethylene glycol di-p-toluenesulfonate in the presence of Cs2CO3. The cone 10a and 10b and the partial cone 11 conformers were obtained by selective demethylation of the 25,27-dimethoxycalix[4]arenecrown-5 (6a) and subsequent dialkylation with NaH/DMF and KOtBu/THF, respectively. In the solid state (X-ray), compound 6a adopts a flattened cone conformation, which is also found to be most abundant in CD3CN and CD3OD solution. Upon complexation with potassium picrate compound 6a was converted quantitatively into the 1,3-alternate conformation. All new ligands synthesized were used in the extraction of alkali metal cations from H2O into CHCl3, and as active components in supported liquid membranes and in chemically modified field effect transistors. Results were compared to those obtained with with the natural antibiotic valinomycin 1. All ligands showed high selectivity for potassium. Ligand 8a, fixed in the 1,3-alternate conformation, is more selective than valinomycin and shows the highest K+/Na+ selectivity known so far.
138 citations
TL;DR: Oligoethylene glycols and some related alcohols were efficiently tosylated with p-toluenesulfonyl chloride in a tetrahydrofuran-water (1:1) mixture in the presence of excess sodium hydroxide as mentioned in this paper.
Abstract: Oligoethylene glycols and some related alcohols were efficiently tosylated with p-toluenesulfonyl chloride in a tetrahydrofuran–water (1:1) mixture in the presence of excess sodium hydroxide. This method is advantageous over the conventional tosylation in pyridine both regarding the work-up procedure, the yield, and the purity of the product, and may be potentially useful for the tosylation of certain acid-labile alcohols.
135 citations
TL;DR: New series of poly(ethylene glycol) (PEG)-functionalized ILs comprising inexpensive alkylammonium or piperidinium cations paired with acetate anions can effectively transform the cellulose I structure to cellulose II, reducing the crystallinity of cellulose and increasing the structural homogeneity.
116 citations