Single-Site Catalysts for Ring-Opening Polymerization:  Synthesis of Heterotactic Poly(lactic acid) from <i>rac</i>-Lactide

Cheng, Ming; Attygalle, Athula B.; Lobkovsky, Emil; Coates, Geoffrey W.

doi:10.1021/ja992678o

Cited by 603 publications

(385 citation statements)

References 11 publications

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“…[22,41] We found that it also catalyzed the terpolymerization. As before, an excess of CHO monomer had to be used to incorporate higher amounts of polycarbonate in the polymer.…”

Section: Terpolymerization Experimentsmentioning

confidence: 92%

“…[14,15] In general, the BDI ligand is of increasing importance for the field of homogeneous catalysis, because it exhibits a strong binding to the metal, a tunable steric demand and a diversity of binding modes. [16] Metal complexes thereof have been used for several catalytic applications such as the oligomerization and polymerization of olefins, [17][18][19] the polymerization of methyl methacrylate, [20] , or the polymerization of lactide [21,22] . For the CO 2 /epoxide copolymerization, tetradentate derivatives of this ligand have been developed to bind rare earth metals [23] as well as to form a rigid bimetallic zinc acetate complex.…”

Section: Introductionmentioning

confidence: 99%

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Alternating Copolymerization of Carbon Dioxide and Cyclohexene Oxide and Their Terpolymerization with Lactide Catalyzed by Zinc Complexes of N,N Ligands

Kröger

Folli²,

Walter³

et al. 2006

Adv Synth Catal

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Abstract:For the alternating copolymerization of CO 2 and cyclohexene oxide, a variety of zinc acetate complexes with new aminoimidoacrylate ligands has been synthesized and tested as catalysts. All complexes catalyzed the reaction and structure-activity investigations revealed that the highest activities and selectivities were reached when the ligand's aromatic rings were 2,6-substituted by alkyl groups of different size (isopropyl versus methyl) and when the ligand backbone embodied an electron-withdrawing cyano group. Furthermore, these complexes catalyzed the terpolymerization of CO 2 , cyclohexene oxide and lactide to give poly(cyclohexyl carbonateco-lactide) and the composition of the polymer was adjustable by the monomer feed.

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“…[22,41] We found that it also catalyzed the terpolymerization. As before, an excess of CHO monomer had to be used to incorporate higher amounts of polycarbonate in the polymer.…”

Section: Terpolymerization Experimentsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Alternating Copolymerization of Carbon Dioxide and Cyclohexene Oxide and Their Terpolymerization with Lactide Catalyzed by Zinc Complexes of N,N Ligands

Kröger

Folli²,

Walter³

et al. 2006

Adv Synth Catal

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“…Non-toxic options are zinc salts or complexes. [1] Because they are mostly colourless, inexpensive and non-toxic [2,3] zinc complexes with N-donor-functionalised ligands, for instance, b-diketiminates [12,13] and Schiff bases, [14] were introduced as active catalysts for the ROP of lactide to enhance the polymerisation process and to replace the common Snbased catalysts. Besides the cationic portion, the influence of the anionic component is important as well.…”

Section: Introductionmentioning

confidence: 99%

Lactide Polymerisation with Air‐Stable and Highly Active Zinc Complexes with Guanidine–Pyridine Hybrid Ligands

Börner

Flörke

Huber

et al. 2009

Chemistry A European J

153

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The synthesis of zinc complexes of guanidine-pyridine hybrid ligands [Zn(DMEGpy)Cl(2)] (C1), [Zn(TMGpy)Cl(2)] (C2), [Zn(DMEGqu)Cl(2)] (C3), [Zn(TMGqu)Cl(2)] (C4), [Zn(DMEGpy)(CH(3)COO)(2)] (C5), [Zn(TMGpy)(CH(3)COO)(2)] (C6), [Zn(DMEGqu)(CH(3)COO)(2)] (C7), [Zn(TMGqu)(CH(3)COO)(2)] (C8), [Zn(DMEGqu)(2)(CF(3)SO(3))][CF(3)SO(3)] (C9) and [Zn(TMGqu)(2)(CF(3)SO(3))][CF(3)SO(3)] (C10) is reported. These zinc complexes were completely characterised and screened regarding their activity in the ring-opening polymerisation of D,L-lactide. They proved to be active initiators in lactide bulk polymerisation, and polylactides with molecular weights (M(w)) up to 176,000 g mol(-1) could be obtained. They combine high activity with robustness towards moisture and air. The influence of reaction temperature and of the anionic component of the zinc salt on the activity of the catalyst, as well as the occurrence of undesired side reactions, was investigated. By correlating these findings with the structural study on the zinc complexes we could deduce a structure-reactivity relationship for the zinc catalysts. This study was accompanied by DFT calculations. The bis-chelate triflate complexes C9 and C10, supported by quinoline-guanidine ligands L3 and L4, exhibit by far the highest reactivity. Systematic comparison of these complexes with their mono-chelate counterparts and their bis-guanidine analogues allows the attributes that promote polymerisation by neutral guanidine ligand systems to be elucidated: accessibility to the zinc centre and Lewis acidity.

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“…[19] Enantioselectivity, in particular, has garnered much attention, and catalysts with exquisite control over PLA tacticity have been reported. [20,21] Two modes of selectivity have been explored, enantiomorphic site control and chain-end control. These modes are not independent of each other; chain-end control can play an important role in systems that exhibit site control.…”

mentioning

confidence: 99%

A Highly Active Chiral Indium Catalyst for Living Lactide Polymerization

2008

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Single-Site Catalysts for Ring-Opening Polymerization: Synthesis of Heterotactic Poly(lactic acid) from rac-Lactide

Cited by 603 publications

References 11 publications

Alternating Copolymerization of Carbon Dioxide and Cyclohexene Oxide and Their Terpolymerization with Lactide Catalyzed by Zinc Complexes of N,N Ligands

Alternating Copolymerization of Carbon Dioxide and Cyclohexene Oxide and Their Terpolymerization with Lactide Catalyzed by Zinc Complexes of N,N Ligands

Lactide Polymerisation with Air‐Stable and Highly Active Zinc Complexes with Guanidine–Pyridine Hybrid Ligands

A Highly Active Chiral Indium Catalyst for Living Lactide Polymerization

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