文献类型：期刊文献

英文题名：Balancing the transesterification reactivity of isosorbide with diphenyl carbonate: preferential activation ofexo-OH

作者：Zhang, Ming[1];Tu, Yifei[1];Zhou, Zibo[1];Wu, Guozhang[1]

机构：[1]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai Key Lab Adv Polymer Mat, Shanghai 200237, Peoples R China

年份：2020

卷号：11

期号：34

起止页码：5512

外文期刊名：POLYMER CHEMISTRY

收录：;EI(收录号：20204209340916);WOS:【SCI-EXPANDED(收录号:WOS:000564460600011)】；

基金：This work was financially supported by the National Natural Science Foundation of China (51873063).

语种：英文

外文关键词：Chemical activation - Density functional theory - Equilibrium constants - Carbonation - Catalysts

摘要：Theexo-hydroxyl group (exo-OH) on isosorbide (ISB) has long been asserted as a highly reactive moiety compared with theendo-hydroxyl group (endo-OH). In this study, calculations based on density functional theory and experiments without adding catalysts reveal thatendo-OH has strong nucleophilic ability, and in the case of transesterification with diphenyl carbonate, the nucleophilic attack surmounts steric hindrance in renderingendo-OH more reactive thanexo-OH. The kinetics of transesterification with different catalysts is investigated to determine the catalytic reactivity and molecular structure evolution. The results show that preferential activation ofexo-OH moieties can be achieved either by reducing the coordination ability of catalytic cations (lg beta(1)) or by enhancing the alkalinity of catalytic anions. Despite the low reactivity ofexo-OH on ISB monomers, terminalexo-OH on carbonate oligomers exhibits higher reactivity than terminalendo-OH, justifying the experimental fact that ISB-based polycarbonates (ISB-PCs) are mostly terminated byendo-OH. Balancing the reactivity betweenendo-OH andexo-OH can be promoted by increasing the reaction temperature, thus accelerating transesterification to a high equilibrium constant. These findings help to clarify the mechanism of ISB transesterification and provide new strategies for the synthesis of high-molecular-weight ISB-PCs.