Organolithium-Initiated Polymerization of Olefins in Deep Eutectic Solvents under Aerobic Conditions.
Organolithium-Initiated Polymerization of Olefins in Deep Eutectic Solvents under Aerobic Conditions.
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DOI：
10.1002/cssc.201900533
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发表时间：
2019-07
期刊：
影响因子：
8.4
通讯作者：
Alba Sánchez‐Condado;G. A. Carriedo;A. Presa Soto;M. J. Rodríguez-Álvarez;Joaquín García‐Álvarez;Eva Hevia
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文献类型：
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作者：
Alba Sánchez‐Condado;G. A. Carriedo;A. Presa Soto;M. J. Rodríguez-Álvarez;Joaquín García‐Álvarez;Eva Hevia
尽管极性有机锂试剂在合成中普遍存在，但在环境友好的条件下使用极性有机锂试剂构成了可持续化学的最大挑战之一。它们的高反应性要求使用严格限制的方案（例如，无湿气和无氧、有毒有机溶剂、惰性气氛、低温等）。为了应对这一挑战，通过在此类转化中率先使用低共熔溶剂（DES）作为环保反应介质，建立了一种新的空气和水分相容性有机锂介导的不同烯烃（例如苯乙烯和乙烯基吡啶）阴离子聚合方法。微调条件（在没有保护气氛的情况下在 40 °C 下对反应混合物进行超声处理）以及仔细选择 DES 的成分 [氯化胆碱 (ChCl) 和甘油 (Gly)，比例为 1:2]，以优异的产率（高达 90%）和低多分散性（IPD 1.1-1.3）提供所需的有机聚合物（均聚物和无规共聚物）。值得注意的是，原位形成的聚苯乙烯锂中间体在低共熔混合物 1ChCl/2Gly 中表现出很强的耐水解性（长达 1.5 小时），这表明这些高反应性有机锂物质在这些非常规反应介质中具有意想不到的高稳定性。这种独特的稳定性可用于创建明确的嵌段共聚物。
Despite their ubiquitous presence in synthesis, the use of polar organolithium reagents under environmentally benign conditions constitutes one of the greatest challenges in sustainable chemistry. Their high reactivity imposes the use of severely restrictive protocols (e.g., moisture- and oxygen-free, toxic organic solvents, inert atmospheres, low temperatures, etc.). Making inroads towards meeting this challenge, a new air- and moisture-compatible organolithium-mediated methodology for the anionic polymerization of different olefins (e.g., styrenes and vinylpyridines) was established by pioneering the use of deep eutectic solvents (DESs) as an eco-friendly reaction medium in this type of transformation. Fine-tuning of the conditions (sonication of the reaction mixture at 40 °C in the absence of protecting atmosphere) along with careful choice of components of the DES [choline chloride (ChCl) and glycerol (Gly) in a 1:2 ratio] furnished the desired organic polymers (homopolymers and random copolymers) in excellent yields (up to 90 %) and low polydispersities (IPD 1.1-1.3). Remarkably, the in situ-formed polystyril lithium intermediates exhibited a great resistance to hydrolysis in the eutectic mixture 1ChCl/2Gly (up to 1.5 h), hinting at an unexpected high stability of these otherwise highly reactive organolithium species in these unconventional reaction media. This unique stability can be exploited to create well defined block-copolymers.