CO2 Chemistry of Phenolate-Based Ionic Liquids

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• 作者：Tae Bum Lee ; Seungmin Oh ; Thomas R. Gohndrone ; Oscar Morales-Collazo ; Samuel Seo ; Joan F. Brennecke ; William F. Schneider
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：March 3, 2016
• 年：2016
• 卷：120
• 期：8
• 页码：1509-1517
• 全文大小：531K
• ISSN：1520-5207

文摘

We synthesized ionic liquids (ILs) comprising an alkylphosphonium cation paired with phenolate, 4-nitrophenolate, and 4-methoxyphenolate anions that span a wide range of predicted reaction enthalpies with CO₂. Each phenolate-based IL was characterized by spectroscopic techniques, and their physical properties (viscosity, conductivity, and CO₂ solubility) were determined. We use the computational quantum chemical approach paired with experimental results to reveal the reaction mechanism of CO₂ with phenolate ILs. Model chemistry shows that the oxygen atom of phenolate associates strongly with phosphonium cations and is able to deprotonate the cation to form an ylide with an affordable activation barrier. The ATR-FTIR and ³¹P NMR spectra indicate that the phosphonium ylide formation and its reaction with CO₂ are predominantly responsible for the observed CO₂ uptake rather than direct anion–CO₂ interaction.