Zn(II)- and Mg(II)-Complexes of a Tridentate {ONN} Ligand: Application to Poly(lactic acid) Production and Chemical Upcycling of Polyesters
Zn(II)- and Mg(II)-Complexes of a Tridentate {ONN} Ligand: Application to Poly(lactic acid) Production and Chemical Upcycling of Polyesters
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DOI：
10.1021/acs.macromol.1c01207
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发表时间：
2021-09
期刊：
影响因子：
5.5
通讯作者：
Jack M. Payne;G. Kociok‐Köhn;E. Emanuelsson;Matthew D. Jones
中科院分区：
文献类型：
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作者：
Jack M. Payne;G. Kociok‐Köhn;E. Emanuelsson;Matthew D. Jones
本文报道了两种基于简单三齿{NNO}配体的同效Zn(II)-和Mg(II)-配合物的合成和表征。在工业相关的熔体条件下，证明了生物相容性无乳酸聚乳酸（PLA）的生产，注意到室温下CH2Cl2（TOF = 184 h-1）中Zn(1)2的高活性。Mg(1)2和Zn(1)2可以促进PLA在温和条件下快速甲醇分解成乳酸甲酯（Me-LA），在50°C的THF条件下，30分钟内Me-LA的产率高达85%。进一步的动力学分析发现，Mg(1)2和Zn(1)2的kapp值分别为0.23±0.0076和0.15±0.0029 min-1 {8 wt % cat。装载}，是迄今为止报道的最高的。Zn(1)2对聚对苯二甲酸乙酯（PET）和聚ε-己内酯（PCL）的降解均保持了良好的活性，证明了催化剂的通用性。采用各种升级回收策略（例如，甲醇解，糖酵解和氨解）来实现广泛的底物范围，其中包括双（2-羟乙基）对苯二甲酸酯（BHET），高价值对苯二甲酸酯和甲基6-羟基己酸酯。最佳糖酵解条件是在180°C下使用Zn(1)2使1 h内bet产率达到64%，这是一个罕见的由离散均相金属基催化剂介导的PET糖酵解的例子。这类催化剂在PET氨解和PCL甲醇解中的应用尚属首次报道。
The synthesis and characterization of two homoleptic Zn(II)- and Mg(II)-complexes based on a simple tridentate {NNO} ligand are reported. The production of biocompatible atactic poly(lactic acid) (PLA) under industrially relevant melt conditions is demonstrated, noting high activity for Zn(1)2at room temperature in CH2Cl2(TOF = 184 h–1). Mg(1)2and Zn(1)2were shown to facilitate rapid PLA methanolysis into methyl lactate (Me-LA) under mild conditions, achieving up to 85% Me-LA yield within 30 min at 50 °C in THF. Further kinetic analysis found Mg(1)2and Zn(1)2to exhibitkappvalues of 0.23 ± 0.0076 and 0.15 ± 0.0029 min–1, respectively {8 wt % cat. loading}, among the highest reported thus far. Zn(1)2retained excellent activity for both poly(ethylene terephthalate) (PET) and poly(ε-caprolactone) (PCL) degradations, demonstrating catalyst versatility. Various upcycling strategies (e.g., methanolysis, glycolysis, and aminolysis) were employed to achieve a broad substrate scope, which included bis(2-hydroxyethyl) terephthalate (BHET), high value terephthalamides, and methyl 6-hydroxyhexanoate. Optimal glycolysis conditions using Zn(1)2enabled 64% BHET yield within 1 h at 180 °C, a rare example of PET glycolysis mediated by a discrete homogeneous metal-based catalyst. The application of such catalysts for PET aminolysis and PCL methanolysis has been reported for the first time.