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Catalysis

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Catalysis - Free Register to Access Experts & Abstracts

Jean-françois Carpentier - One of the best experts on this subject based on the ideXlab platform.

  • Beyond Stereoselectivity, Switchable Catalysis: Some of the Last Frontier Challenges in Ring-Opening Polymerization of Cyclic Esters
    Chemistry - A European Journal, 2015
    Co-Authors: Sophie M. Guillaume, Evgueni Kirillov, Yann Sarazin, Jean-françois Carpentier
    Abstract:

    Metal-based catalysts and initiators have played a pivotal role in the ring-opening polymerization (ROP) of cyclic esters, thanks to their high activity and remarkable ability to control precisely the architectures of the resulting polyesters in terms of molar mass, dispersity, microstructure, or tacticity. Today, after two decades of extensive research, the field is slowly reaching maturity. However, several challenges remain, while original concepts have emerged around new types or new applications of Catalysis. This Review is not intended to comprehensively cover all of these aspects. Rather, it provides a personal overview of the very recent progress achieved in some selected, important aspects of ROP Catalysis-stereocontrol and switchable Catalysis. Hence, the first part addresses the development of new metal-based catalysts for the isoselective ROP of racemic lactide towards stereoblock copolymers, and the use of syndioselective ROP metal catalysts to control the monomer sequence in copolymers. A second part covers the development of ROP catalysts-primarily metal-based catalysts, but also organocatalysts-that can be externally regulated by the use of chemical or photo stimuli to switch them between two states with different catalytic abilities. Current challenges and opportunities are highlighted.

  • Beyond Stereoselectivity, Switchable Catalysis: Some of the Last Frontier Challenges in Ring‐Opening Polymerization of Cyclic Esters
    Chemistry: A European Journal, 2015
    Co-Authors: Sophie M. Guillaume, Evgueni Kirillov, Yann Sarazin, Jean-françois Carpentier
    Abstract:

    Metal-based catalysts and initiators have played a pivotal role in the ring-opening polymerization (ROP) of cyclic esters, thanks to their high activity and remarkable ability to control precisely the architectures of the resulting polyesters in terms of molar mass, dispersity, microstructure, or tacticity. Today, after two decades of extensive research, the field is slowly reaching maturity. However, several challenges remain, while original concepts have emerged around new types or new applications of Catalysis. This Review is not intended to comprehensively cover all of these aspects. Rather, it provides a personal overview of the very recent progress achieved in some selected, important aspects of ROP Catalysis-stereocontrol and switchable Catalysis. Hence, the first part addresses the development of new metal-based catalysts for the isoselective ROP of racemic lactide towards stereoblock copolymers, and the use of syndioselective ROP metal catalysts to control the monomer sequence in copolymers. A second part covers the development of ROP catalysts-primarily metal-based catalysts, but also organocatalysts-that can be externally regulated by the use of chemical or photo stimuli to switch them between two states with different catalytic abilities. Current challenges and opportunities are highlighted.

Sophie M. Guillaume - One of the best experts on this subject based on the ideXlab platform.

  • Beyond Stereoselectivity, Switchable Catalysis: Some of the Last Frontier Challenges in Ring-Opening Polymerization of Cyclic Esters
    Chemistry - A European Journal, 2015
    Co-Authors: Sophie M. Guillaume, Evgueni Kirillov, Yann Sarazin, Jean-françois Carpentier
    Abstract:

    Metal-based catalysts and initiators have played a pivotal role in the ring-opening polymerization (ROP) of cyclic esters, thanks to their high activity and remarkable ability to control precisely the architectures of the resulting polyesters in terms of molar mass, dispersity, microstructure, or tacticity. Today, after two decades of extensive research, the field is slowly reaching maturity. However, several challenges remain, while original concepts have emerged around new types or new applications of Catalysis. This Review is not intended to comprehensively cover all of these aspects. Rather, it provides a personal overview of the very recent progress achieved in some selected, important aspects of ROP Catalysis-stereocontrol and switchable Catalysis. Hence, the first part addresses the development of new metal-based catalysts for the isoselective ROP of racemic lactide towards stereoblock copolymers, and the use of syndioselective ROP metal catalysts to control the monomer sequence in copolymers. A second part covers the development of ROP catalysts-primarily metal-based catalysts, but also organocatalysts-that can be externally regulated by the use of chemical or photo stimuli to switch them between two states with different catalytic abilities. Current challenges and opportunities are highlighted.

  • Beyond Stereoselectivity, Switchable Catalysis: Some of the Last Frontier Challenges in Ring‐Opening Polymerization of Cyclic Esters
    Chemistry: A European Journal, 2015
    Co-Authors: Sophie M. Guillaume, Evgueni Kirillov, Yann Sarazin, Jean-françois Carpentier
    Abstract:

    Metal-based catalysts and initiators have played a pivotal role in the ring-opening polymerization (ROP) of cyclic esters, thanks to their high activity and remarkable ability to control precisely the architectures of the resulting polyesters in terms of molar mass, dispersity, microstructure, or tacticity. Today, after two decades of extensive research, the field is slowly reaching maturity. However, several challenges remain, while original concepts have emerged around new types or new applications of Catalysis. This Review is not intended to comprehensively cover all of these aspects. Rather, it provides a personal overview of the very recent progress achieved in some selected, important aspects of ROP Catalysis-stereocontrol and switchable Catalysis. Hence, the first part addresses the development of new metal-based catalysts for the isoselective ROP of racemic lactide towards stereoblock copolymers, and the use of syndioselective ROP metal catalysts to control the monomer sequence in copolymers. A second part covers the development of ROP catalysts-primarily metal-based catalysts, but also organocatalysts-that can be externally regulated by the use of chemical or photo stimuli to switch them between two states with different catalytic abilities. Current challenges and opportunities are highlighted.

David W. Lupton - One of the best experts on this subject based on the ideXlab platform.

  • lewis base Catalysis of three n π mediated reactions with n heterocyclic carbenes nhcs isothioureas bicyclic tertiary amines and electron rich pyridyls
    Synthesis, 2014
    Co-Authors: Lisa Candish, Yuji Nakano, David W. Lupton
    Abstract:

    Lewis base Catalysis by lone pair donation into anti-bonding π orbitals (n–π*) is a growing field with a range of Lewis bases capable of this type of Catalysis. In this review, Catalysis of the Morita–Baylis–Hillman reaction, the Steglich rearrangement, and the annulation of α,β-unsaturated acyl Lewis adducts are discussed, using N-heterocyclic carbene (NHC), isothiourea, bicyclic tertiary amine and electron-rich pyridyl catalysts. In many cases, each of these popular Lewis base catalysts is viable for the given reaction, with the degree of utility defined by the catalyst’s nucleophilicity and Lewis basicity. 1 Introduction to Lewis Base Catalysis 2 Enolates from 1,4-Addition: Morita–Baylis–Hillman Reaction 3 O→C Carboxyl Transfer: Steglich Rearrangement 4 Annulations of α,β-Unsaturated Acyl Lewis Base Adducts 5 Summary and Outlook

  • Lewis Base Catalysis of Three n–π* Mediated Reactions with N-Heterocyclic Carbenes (NHCs), Isothioureas, Bicyclic Tertiary Amines, and Electron-Rich Pyridyls
    Synthesis, 2014
    Co-Authors: Lisa Candish, Yuji Nakano, David W. Lupton
    Abstract:

    Lewis base Catalysis by lone pair donation into anti-bonding π orbitals (n–π*) is a growing field with a range of Lewis bases capable of this type of Catalysis. In this review, Catalysis of the Morita–Baylis–Hillman reaction, the Steglich rearrangement, and the annulation of α,β-unsaturated acyl Lewis adducts are discussed, using N-heterocyclic carbene (NHC), isothiourea, bicyclic tertiary amine and electron-rich pyridyl catalysts. In many cases, each of these popular Lewis base catalysts is viable for the given reaction, with the degree of utility defined by the catalyst’s nucleophilicity and Lewis basicity. 1 Introduction to Lewis Base Catalysis 2 Enolates from 1,4-Addition: Morita–Baylis–Hillman Reaction 3 O→C Carboxyl Transfer: Steglich Rearrangement 4 Annulations of α,β-Unsaturated Acyl Lewis Base Adducts 5 Summary and Outlook

Ning Jiao - One of the best experts on this subject based on the ideXlab platform.

Calogero G Piscopo - One of the best experts on this subject based on the ideXlab platform.

  • supported sulfonic acids solid catalysts for batch and continuous flow synthetic processes
    ChemistryOpen, 2015
    Co-Authors: Calogero G Piscopo
    Abstract:

    In recent years the need to reduce production costs and the increasing regulations in pollution prevention prompted industries and academia to revise old processes for fine chemical and pharmaceutical synthesis. A powerful tool to enhance the sustainability of chemical processes is, undoubtedly, heterogeneous Catalysis, which allows a few improvements over homogeneous Catalysis and can help develop cleaner, safer, and more economically feasible processes. In the field of heterogeneous Catalysis, two preferential methods have been developed: the use of polymer-supported catalysts and the use of solid inorganic oxide catalysts. In the last years, much effort has been devoted to the heterogenization of catalysts, and different strategies have been developed for the preparation of supported homogeneous catalysts.