Abstract

The hunt for sustainable solvents has been an expansive pursuit ever since the genesis of green chemistry and has yielded more ecological approaches involving new organic compounds that are simultaneously used as reaction media and catalysts, such as neoteric solvents. This work primarily investigated the suitability of various ionic liquids (ILs) as a reaction medium for chemical generation of superoxide radical anions (\({\text{O}}_{2}^{{\bullet - }}\)). This was achieved by monitoring the stability of \({\text{O}}_{2}^{{\bullet - }}\) over a period of 3 h via kinetic studies in the presence of ILs comprising ammonium, pyrrolidinium, imidazolium, guanidinium, morpholinium, and sulfonium-based cations combined with different anions, such as [TFSI]⁻, [TfO]⁻, [DCA]⁻, [DMP]⁻, [TCB]⁻, [FAP]⁻, [E₃FAP]⁻, [EtSO₄]⁻, [SCN]⁻, [Cl]⁻, and [I]⁻. Potassium superoxide (KO₂) salt, generated by dissolution of KO₂ in DMSO, was used as the source of \({\text{O}}_{2}^{{\bullet - }}\). Pursuant to our recent familiarity with literature, this work represents the first use of a guanidinium-based IL in the study of \({\text{O}}_{2}^{{\bullet - }}\) stability. Following screening, it was found that consumption of generated \({\text{O}}_{2}^{{\bullet - }}\) was highest in the presence of [C₄DMIm][I], at 35.25%. This highlights its instability in that medium. In contrast, \({\text{O}}_{2}^{{\bullet - }}\) was generated as a well-stabilized species in DMSO containing [BMIm][Cl], [BMIm][TfO], [BMIm][TFSI], [PMIm][TFSI], [EMIm][TFSI], [TBAmm][TFSI], [EDMPAmm][TFSI], [N₂₁₁,mom][E₃FAP], [BMPyrr][TCB], [MOPyrr][TFSI], and [MOEMMo][TFSI]. Of the 22 ILs analyzed in this study, the lowest total consumption of \({\text{O}}_{2}^{{\bullet - }}\) was observed in morpholinium-based IL at 0.04%, positioning it as the best medium for the chemical generation of \({\text{O}}_{2}^{{\bullet - }}\).

中文翻译：

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含二甲亚砜离子液体中超氧自由基阴离子的筛选稳定性和动力学

摘要

自绿色化学诞生以来，对可持续溶剂的探索一直是一个广泛的追求，并产生了更多生态方法，涉及同时用作反应介质和催化剂的新型有机化合物，例如近代溶剂。这项工作主要研究了各种离子液体（IL）作为化学生成超氧自由基阴离子（\({\text{O}}_{2}^{{\bullet - }}\) ）的反应介质的适用性。这是通过在包含铵、吡咯烷鎓、咪唑鎓、胍鎓、吗啉鎓和锍基阳离子与不同阴离子结合，如[TFSI] ^-、[TfO] ^-、[DCA] ^-、[DMP] ^-、[TCB] ^-、[FAP] ^-、[E ₃ FAP] ^-、[EtSO ₄ ] ^-、[SCN] ^-、[Cl] ^-和[I] ^-。_{通过将 KO 2}溶解在 DMSO 中生成的超氧化钾 (KO _{2 ) 盐被用作}\({\text{O}}_{2}^{{\bullet - }}\)的来源。根据我们最近对文献的熟悉程度，这项工作代表了基于胍盐的离子液体在\({\text{O}}_{2}^{{\bullet - }}\)稳定性研究中的首次使用。经过筛选，发现在 [C _{4 DMIm][I] 存在的情况下，生成的}\({\text{O}}_{2}^{{\bullet - }}\)的消耗最高，为 35.25 %。这凸显了它在该介质中的不稳定性。相反，\({\text{O}}_{2}^{{\bullet - }}\)是在含有 [BMIm][Cl]、[BMIm][TfO] 的 DMSO 中生成的稳定良好的物质。 , [BMIm][TFSI], [PMIm][TFSI], [EMIm][TFSI], [TBAmm][TFSI], [EDMPAmm][TFSI], [N ₂₁₁ ,mom][E ₃ FAP], [BMPyrr ][TCB]、[MOPyrr][TFSI] 和 [MOEMMo][TFSI]。在本研究分析的 22 种 IL 中，基于吗啉的 IL的总消耗量\({\text{O}}_{2}^{{\bullet - }}\)最低，为 0.04%，将其定位为作为化学生成\({\text{O}}_{2}^{{\bullet - }}\) 的最佳介质。