TY - JOUR
T1 - Zn(II)- And Mg(II)-Complexes of a Tridentate {ONN} Ligand
T2 - Application to Poly(lactic acid) Production and Chemical Upcycling of Polyesters
AU - Payne, Jack
AU - Kociok-Kohn, Gabriele
AU - Emanuelsson, Emma Anna Carolina
AU - Jones, Matthew
N1 - Funding Information:
We wish to thank the EPSRC for funding and the University of Bath and MC for use of their analysis facilities. We would like to thank the EPSRC for funding (EP/L016354/1) for a PhD studentship to J.P. 2
PY - 2021/9/28
Y1 - 2021/9/28
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85115925157&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.1c01207
DO - 10.1021/acs.macromol.1c01207
M3 - Article
VL - 54
SP - 8453
EP - 8469
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 18
ER -