Klemes Max J, Ling Yuhan, Chiapasco Marta, Alsbaiee Alaaeddin, Helbling Damian E, Dichtel William R
Department of Chemistry , Northwestern University , Evanston , IL 60208 , USA . Email:
School of Civil and Environmental Engineering , Cornell University , Ithaca , NY 14853 , USA.
Chem Sci. 2018 Sep 24;9(47):8883-8889. doi: 10.1039/c8sc03267j. eCollection 2018 Dec 21.
Porous β-cyclodextrin polymers linked with tetrafluoroterephthalonitrile (TFN-CDPs) have shown promise for adsorbing organic micropollutants (MPs) more quickly and effectively than conventional adsorbents. Prior to their discovery, the nucleophilic aromatic substitution (SAr) reaction used to prepare TFN-CDP was nearly unknown for the aliphatic alcohol nucleophiles, and the low isolated yields of TFN-CDP motivated model studies of the reaction between TFN and -butanol. These experiments reveal a previously undescribed substitution reaction of TFN in which a fluorine is substituted by a hydroxyl group. This process is responsible for the low yields of the polymerization and incorporates phenolate groups into the polymer network. Phenolation and polymerization (etherification) are competing processes, and the level of phenolate incorporation was controlled by varying the rate of base addition and initial monomer concentrations. TFN-CDPs with varying phenolate content were prepared and evaluated as adsorbents for both Pb ions and 83 MPs. More heavily phenolated polymers showed increased capacity to bind Pb ions. Phenolation was also correlated with increased binding affinity for almost all of the 83 MPs tested, including neutral, cationic, and anionic substances. These results leverage a newly discovered side reaction during SAr reactions of electron-poor aryl fluorides to improve both the yield and the uptake affinity for both lead and organic MPs of TFN-CDPs.
与四氟对苯二甲腈连接的多孔β-环糊精聚合物（TFN-CDPs）已显示出比传统吸附剂更快、更有效地吸附有机微污染物（MPs）的潜力。在其被发现之前，用于制备TFN-CDP的亲核芳香取代（SAr）反应对于脂肪醇亲核试剂几乎是未知的，并且TFN-CDP的低分离产率促使对TFN与正丁醇之间的反应进行模型研究。这些实验揭示了TFN一种先前未描述的取代反应，其中一个氟被一个羟基取代。这个过程导致了聚合反应的低产率，并将酚盐基团纳入聚合物网络。酚化和聚合（醚化）是竞争过程，通过改变碱的添加速率和初始单体浓度来控制酚盐的掺入水平。制备了具有不同酚盐含量的TFN-CDPs，并将其作为Pb离子和83种MPs的吸附剂进行评估。酚化程度更高的聚合物对Pb离子的结合能力增强。酚化还与对几乎所有83种测试MPs的结合亲和力增加相关，包括中性、阳离子和阴离子物质。这些结果利用了贫电子芳基氟化物SAr反应过程中新发现的副反应，提高了TFN-CDPs对铅和有机MPs的产率和吸附亲和力。
