Abstract

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 CH 2Cl 2(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 exhibitk appvalues 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.

Original languageEnglish
Pages (from-to)8453-8469
Number of pages17
JournalMacromolecules
Volume54
Issue number18
Early online date13 Sep 2021
DOIs
Publication statusPublished - 28 Sep 2021

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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