Ligand Design in Enantioselective Ring‐opening Polymerization of Lactide

Osten, Kimberly M.; Aluthge, Dinesh C.; Mehrkhodavandi, Parisa

doi:10.1002/9781118839621.ch10

Cited by 3 publications

(2 citation statements)

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“…It was shown that ZnEt 2 promoted with [PhNHMe 2 ][B(C 6 F 5 ) 4 ] is an efficient catalyst for the intramolecular hydroamination of aminoolefins and aminoalkynes, while the zinc sandwich complex [Zn 2 Cp* 2 ][B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 ] obtained by the reaction of Cp* 2 Zn with [H(OEt 2 ) 2 ][B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 ] was successfully employed for catalytic intra- and intermolecular hydroamination . Great versatility and potential in ROP of cyclic esters was shown by indium complexes, − while cationic salene indium complexes exhibited the best performance . CAAC-supported (CAAC = cyclic (alkyl)(amino)carbene = 1-[2,6-bis(1-methylethyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene) cationic species based on ZnMe 2 effectively mediates alkene, alkyne, and CO 2 hydrosilylation …”

Section: Introductionmentioning

confidence: 99%

Synthesis and ε-Caprolactone Polymerization Activity of Electron-Deficient Gallium and Aluminum Species Containing a Charged Redox-Active dpp-Bian Ligand

et al. 2019

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The synthesis of electron-deficient gallium- and aluminum-centered species containing a redox-active dpp-Bian ligand (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) is described. The reaction of digallane [(dpp-Bian)Ga–Ga(dpp-Bian)] with [Ph3C][PF6] or AgPF6 resulted in polyoxidized species [(dpp-Bian)GaF2]2 (1), [(dpp-Bian)H2][PF6] (2), and [(dpp-Bian)GaF(O2PF2)]2 (3). The reaction of digallane with B(C6F5)3 led to electron-deficient gallylene [(dpp-Bian)GaB(C6F5)3] 4 of a dpp-Bian radical anion. The soft oxidation of digallane with tosyl cyanide gave the trinuclear cationic species [(dpp-Bian)Ga(Tos)3Ga(Tos)3Ga(dpp-Bian)][Ga(CN)4] (5) containing dpp-Bian radical anions. The reaction of [(dpp-Bian)AlEt2] with 1 equiv of [Ph3C][B(C6F5)4] resulted in the cationic complex [(dpp-Bian)AlEt2][B(C6F5)4] (6) of neutral dpp-Bian, while the treatment of [(dpp-Bian)AlEt(Et2O)] with 1 equiv of [Ph3C][B(C6F5)4] resulted in the compound [(dpp-Bian)AlEt(Et2O)][B(C6F5)4] (7) of a dpp-Bian radical anion. The reaction of diethylaluminum derivative [(dpp-Bian)AlEt2] with 1 equiv of B(C6F5)3 gave the cationic complex [{(dpp-Bian)AlEt}2F][EtB(C6F5)3] (8) containing radical-anion dpp-Bian ligands. The paramagnetic compounds 1, 2, 4, 5, 7, and 8 were characterized by electron paramagnetic resonance spectroscopy, and the diamagnetic complex 6 was characterized by NMR spectroscopy. The molecular structures of 1–6 and 8 were established by single-crystal X-ray diffraction analysis. Compounds 4 and 6–8 were found to be active initiators for immortal ring-opening polymerization of ε-caprolactone.

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Section: Introductionmentioning

confidence: 99%

Synthesis and ε-Caprolactone Polymerization Activity of Electron-Deficient Gallium and Aluminum Species Containing a Charged Redox-Active dpp-Bian Ligand

et al. 2019

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“…For the ROP of rac ‐lactide P m =1 ( P r =0) and P r =1 ( P m =0) indicated ideal isotactic and heterotactic polymers respectively. A value less than 1 for P m and P r indicate a decrease of stereocontrol for the polymerization reaction with a completely atactic polymer having P m or P r =0.5 [19] . The value of P m and P r can be calculated from the integration of the tetrads and using mathematical expressions (Table 1) derived on the basis of Bernoullian statistics and first‐order Markov process [20] .…”

Section: General Considerationsmentioning

confidence: 99%

Determination of Polylactide Microstructure by Homonuclear Decoupled ¹H NMR Spectroscopy

Roy

Sarkar

Chakraborty

2021

The Chemical Record

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The ring‐opening polymerization (ROP) of lactide (the dilactone of lactic acid) produces poly(lactide) commonly referred to as poly(lactic acid) (PLA). The monomer lactide, has two stereogenic centers and thus, three stereoisomers are possible, namely: D‐(R,R), L‐(S,S) and meso‐lactide. The rac‐lactide is an equimolar mixture of D‐ and L‐enantiomers. Depending upon the relative configuration of the stereogenic centers in the polymeric chain, different tacticities (isotactic, syndiotactic, heterotactic and atactic) arise in the PLA chains. The study of the tacticity of a polymer is fundamental since it plays a crucial role in determining the physical properties of the polymer. NMR spectroscopy is a powerful analytical technique for the determination of the tacticity of PLA. This article describes in details the tacticity assignment for PLA derived from ROP of rac‐lactide and meso‐lactide, using homonuclear proton‐decoupled 1H NMR. The detailed tetrad level assignment pertinent to the methine hydrogen signal is the key for the determination of tacticity.

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The Contribution of Commercial Metal Amides to the Chemical Recycling of Waste Polyesters

Santulli¹,

Lamberti²,

Annunziata³

et al. 2022

Catalysts

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Simple and commercially available metal amides are investigated as catalysts for the chemical depolymerization of polyesters of commercial interest such as polylactide (PLA) and polyethylene terephthalate (PET) via alcoholysis. In the alcoholysis reactions performed with methanol or ethanol at room temperature, Zn, Mg, and Y amides showed the highest activities, while the amides of group 4 metals were revealed as poor catalysts. During the ethanolysis of PLA at higher temperatures and the glycolysis of PET, the good activity of the Zn amide was preserved, while for Mg and Y amides, a significant decrease was observed. The reaction temperature had an opposite effect on the performance of group 4 amides, with the Zr amide revealed to be the best catalyst in the PET glycolysis, reaching activities comparable to the best ones reported in the literature for metal catalysts (78% BHET yield within one hour at 180 °C). These studies represent new opportunities for the sustainable recycling of plastics, which are currently being used on a large scale, and provide significant contributions to the design of a circular economy model in the plastic industry.

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Ligand Design in Enantioselective Ring‐opening Polymerization of Lactide

Cited by 3 publications

References 164 publications

Synthesis and ε-Caprolactone Polymerization Activity of Electron-Deficient Gallium and Aluminum Species Containing a Charged Redox-Active dpp-Bian Ligand

Synthesis and ε-Caprolactone Polymerization Activity of Electron-Deficient Gallium and Aluminum Species Containing a Charged Redox-Active dpp-Bian Ligand

Determination of Polylactide Microstructure by Homonuclear Decoupled ¹H NMR Spectroscopy

The Contribution of Commercial Metal Amides to the Chemical Recycling of Waste Polyesters

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Ligand Design in Enantioselective Ring‐opening Polymerization of Lactide

Cited by 3 publications

References 164 publications

Synthesis and ε-Caprolactone Polymerization Activity of Electron-Deficient Gallium and Aluminum Species Containing a Charged Redox-Active dpp-Bian Ligand

Synthesis and ε-Caprolactone Polymerization Activity of Electron-Deficient Gallium and Aluminum Species Containing a Charged Redox-Active dpp-Bian Ligand

Determination of Polylactide Microstructure by Homonuclear Decoupled 1H NMR Spectroscopy

The Contribution of Commercial Metal Amides to the Chemical Recycling of Waste Polyesters

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Determination of Polylactide Microstructure by Homonuclear Decoupled ¹H NMR Spectroscopy