Computational insight into the mechanism and origin of high regioselectivity in the ring-opening cyclization of spirocyclopropanes with stabilized sulfonium ylides by the DFT

Pentacoordinate Al catalysts comprising bipyridine (bpy) and phenanthroline (phen) backbones were synthesized, their activity in epoxide/anhydride copolymerization studied, and the products of stoichiometric ring-opening of anhydrides characterized.

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A New Insight Into the Mechanism of the Ring-Opening Polymerization of Trimethylene Carbonate Catalyzed by Methanesulfonic Acid

Macromolecular Chemistry and Physics ◽

10.1002/macp.201200433 ◽

2012 ◽

Vol 214 (1) ◽

pp. 85-93 ◽

Cited By ~ 12

Author(s):

João M. Campos ◽

Maria R. Ribeiro ◽

Maria F. Ribeiro ◽

Alain Deffieux ◽

Frédéric Peruch

Keyword(s):

Ring Opening ◽

Methanesulfonic Acid ◽

Ring Opening Polymerization ◽

Trimethylene Carbonate ◽

Insight Into

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Structural Analysis ofPseudomonas1-Aminocyclopropane-1-carboxylate Deaminase Complexes: Insight into the Mechanism of a Unique Pyridoxal-5‘-phosphate Dependent Cyclopropane Ring-Opening Reaction†,‡

Biochemistry ◽

10.1021/bi048878g ◽

2004 ◽

Vol 43 (42) ◽

pp. 13328-13339 ◽

Cited By ~ 23

Author(s):

Subramanian Karthikeyan ◽

Qingxian Zhou ◽

Zongbao Zhao ◽

Chai-Lin Kao ◽

Zhihua Tao ◽

...

Keyword(s):

Structural Analysis ◽

Ring Opening ◽

Cyclopropane Ring ◽

Ring Opening Reaction ◽

Insight Into

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Multiblock silicones, 1 Vinyl functionalized polydimethylsiloxane a

e-Polymers ◽

10.1515/epoly.2003.3.1.111 ◽

2003 ◽

Vol 3 (1) ◽

Cited By ~ 3

Author(s):

Carine Ivanenko ◽

Catherine Maitre ◽

François Ganachaud ◽

Patrick Hémery

Keyword(s):

Ring Opening ◽

Ring Opening Polymerization ◽

Multiblock Copolymers ◽

Chain Reactions ◽

Anionic Ring ◽

Interface Propagation ◽

Dispersed Media ◽

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Abstract The first part of this series is devoted to the preparation of vinyl functionalized multiblock silicones by the process of anionic ring opening polymerization in miniemulsion. The advantage of working in dispersed media is that different scales of reactivities are found between one-chain reactions, taking place at the interface (propagation, backbiting), and two-chain reactions, located in the bulk of the particles (polycondensation and intermolecular redistribution). First, homopolymerizations of octamethylcyclotetrasiloxane (D4) and tetramethyltetravinylcyclotetrasiloxane (D4 V) were carried out and compared, focusing specifically on the rates of polymerization, backbiting and polycondensation processes. Copolymerization of D4 with D4 V then gave insight into the extent of mixed cycles’ formation and particularly how to avoid these. On this basis, recipes were carefully selected so that homopolymerization and scarce co-polycondensation and redistribution progress at the expense of backbiting reactions and thus multiblock copolymers are formed, the microstructure of which was confirmed with 29Si NMR.

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Copolymerization of D,L-lactide and ε-caprolactone using tin(II) octanoate as catalysts: an insight into copolymer microstructure

Journal of the Belarusian State University Chemistry ◽

10.33581/2520-257x-2020-2-43-49 ◽

2020 ◽

pp. 43-49

Author(s):

Sergei V. Kostjuk

Keyword(s):

Ring Opening ◽

Early Stage ◽

Random Copolymer ◽

Transesterification Reaction ◽

Copolymer Microstructure ◽

Insight Into

Sn(Oct)2-catalyzed ring-opening copolymerization of D,L-lactide and e-caprolactone in bulk at 130 °C at different D,L-lactide/e-caprolactone has been studied. It was shown that independent on the initial comonomers ratio, the synthesized copolymers are enriched by D,L-lactide at the early stage of reaction indicating the formation of gradient-like copolymer. However, the intensive transesterification reaction both during the polymerization and at the monomer-starved conditions leads to the redistribution of the monomer sequences and formation of the random copolymer. The synthesized copolymers are characterized by high polydispersity (Đ > 2.0), which raises when the reaction mixture was kept under monomer-starved conditions that confirms the occurrence of transesterification. The formation of random copolymer is confirmed by single Tg value, which gradually increased with the increase of the amount of D,L-lactide in the copolymer from –48.6 °C to 33.3 °C for D,L-lactide/e-caprolactone ratio in copolymer of 20:80 and 90:10 mol/mol, respectively.

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Mechanistic Insight into the Ring-Opening Polymerization of ɛ-Caprolactone and L-Lactide Using Ketiminate-Ligated Aluminum Catalysts

Polymers ◽

10.3390/polym11091530 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1530 ◽

Cited By ~ 3

Author(s):

Lin ◽

Jheng

Keyword(s):

Thermal Effects ◽

Ring Opening ◽

Density Functional ◽

Bond Cleavage ◽

Ring Opening Polymerization ◽

Catalyst Design ◽

Reaction Conditions ◽

Functional Theory ◽

Cleavage Step ◽

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The reactivity and the reaction conditions of the ring-opening polymerization of ɛ-caprolactone (ɛ-CL) and L-lactide (LA) initiated by aluminum ketiminate complexes have been shown differently. Herein, we account for the observation by studying the mechanisms on the basis of density functional theory (DFT) calculations. The calculations show that the ring-opening polymerization of ɛ-CL and LA are rate-determined by the benzoxide insertion and the C–O bond cleavage step, respectively. Theoretical computations suggest that the reaction temperature of L–LA polymerization should be higher than that of ɛ-CL one, in agreement with the experimental data. To provide a reasonable interpretation of the experimental results and to give an insight into the catalyst design, the influence of the electronic, steric, and thermal effects on the polymerization behaviors will be also discussed in this study.

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