- Reversible and robust CO2 capture by equimolar task-specific ionic liquid-superbase mixtures
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Integrated sorption systems consisting of 1:1 mixtures of an alcohol-functionalized ionic liquid and a superbase were found to be effective for CO2 capture under atmospheric pressure, eliminating the use of volatile n-alkanols or water. Conversely, by using the current approach, there is no longer a requirement for maintaining scrupulously dry conditions. The effect of ionic liquid structure, choice of superbase, their relative ratios, the sorption temperature, and the reaction time on the absorption and release of CO2 were investigated. Our results demonstrate that (i) this integrated ionic liquid-superbase system is capable of rapid and reversible capture of nearly one mole of CO2 per mole of superbase, (ii) the captured CO2 can be readily released by either mild heating or bubbling with an insert gas (N2, Ar), and (iii) this novel CO 2 chemisorption platform can be recycled with minimal loss of activity. This efficient and fully reversible catch-and-release process using non-volatile, task-specific ionic liquids provides an excellent alternative to current CO2 capture technologies, which are based largely around volatile alkanols or alkylamines. Furthermore, our integrated ionic liquid-superbase system can be used as a novel medium for supported liquid membranes, for which they demonstrate both good selectivity and permeability in model CO2/N2 gas separations.
- Wang, Congmin,Mahurin, Shannon M.,Luo, Huimin,Baker, Gary A.,Li, Haoran,Dai, Sheng
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scheme or table
p. 870 - 874
(2010/09/04)
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- Novel, Very Strong, Uncharged Auxiliary Bases; Design and Synthesis of Monomeric and Polmer-Bound Triaminoiminophosphorane Bases of Broadly Varied Steric Demand
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The synthesis and properties of a number of very strong iminophosphorane bases up to an extremely high level of steric hindrance are described.They cover a range of ca. 4 pK units in basicity and a range of more than 11 orders of magnitude in their rates of methylation with methyl iodide.Most of the systems are readily prepared in up to molar quantities, conveniently recovered from their salts and are of high chemical and thermal stability.Crystal structures were determined in order to parametrize a force field, which is utilized in molecular modeling studies offering a rationalization of the observed differences in steric hindrance and basicity.Depending on the degree of steric protection of the basic center, these novel bases are proposed as unprecedented, versatile auxiliary bases in E2 eliminations and in reactions involving deprotonation in the presence of more or less strong electrophiles. - Key Words: Uncharged auxiliary bases / Triaminoiminophosphorane bases / Deprotonation / Hindered bases / Polymeric bases
- Schwesinger, Reinhard,Willaredt, Juergen,Schlemper, Helmut,Keller, Manfred,Schmitt, Dieter,Fritz, Hans
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p. 2435 - 2454
(2007/10/02)
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