scholarly journals Metal-Free Stereoselective Cationic Polymerization of Vinyl Ethers by Employing a Confined Brønsted Acid as the Catalyst

2021 ◽  
Author(s):  
Zan Yang ◽  
Xun Zhang ◽  
Yu Jiang ◽  
Qiang Ma ◽  
Saihu Liao
Keyword(s):  
Cationic Polymerization ◽  
Lewis Acids ◽  
High Efficiency ◽  
Catalyst System ◽  
Catalyst Loading ◽  
Vinyl Ethers ◽  
System Operation ◽  
Metal Free ◽  
High Degree ◽  
High Stereoselectivity

The properties of poly(vinyl ether)s (PVEs) are highly dependent on their tacticity, and the appealing thermoplastics features of isotactic PVEs have drawn considerable efforts to develop stereoselective cationic polymerization methods to access this class of polymers. However, re-ported methods that could achieve a high degree of tacticity control are limited to process employing metal-based Lewis acids, and with various limitations on catalyst loading, monomer scope, etc. Here, we introduce a metal-free stereoselective cationic polymerization of vinyl ethers by employing a class of chiral confined Brønsted acids, imidodiphos-phorimidates (IDPis), as the catalyst. This organocatalytic approach features its metal free conditions, high efficiency, high stereoselectivity, single catalyst system, operation simplicity, etc.

Structure Effects of Lewis Acids on the Living Cationic Polymerization ofp-Methoxystyrene: Distinct Difference in Polymerization Behavior from Vinyl Ethers

2012 ◽  
Vol 45 (19) ◽  
pp. 7749-7757 ◽  
Author(s):  
Arihiro Kanazawa ◽  
Shota Shibutani ◽  
Nobuto Yoshinari ◽  
Takumi Konno ◽  
Shokyoku Kanaoka ◽  
...  
Keyword(s):  
Cationic Polymerization ◽  
Lewis Acids ◽  
Distinct Difference ◽  
Vinyl Ethers ◽  
Living Cationic Polymerization ◽  
Polymerization Behavior

Effects of monomer and ether structure on metal-free living cationic polymerization of various vinyl ethers using hydrogen chloride with ether

2009 ◽  
Vol 64 (3) ◽  
pp. 209-220 ◽  
Author(s):  
Shinji Sugihara ◽  
Masaru Kitagawa ◽  
Yuichi Inagawa ◽  
Izabela Magdalena Zaleska ◽  
Isao Ikeda
Keyword(s):  
Hydrogen Chloride ◽  
Cationic Polymerization ◽  
Vinyl Ethers ◽  
Free Living ◽  
Metal Free ◽  
Living Cationic Polymerization

scholarly journals Quasi-graphitic carbon shell-induced Cu confinement promotes electrocatalytic CO2 reduction toward C2+ products

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ji-Yong Kim ◽  
Deokgi Hong ◽  
Jae-Chan Lee ◽  
Hyoung Gyun Kim ◽  
Sungwoo Lee ◽  
...  
Keyword(s):  
High Efficiency ◽  
Co2 Reduction ◽  
Value Added ◽  
Material Design ◽  
Catalyst System ◽  
Critical Issue ◽  
Reduction Reaction ◽  
Catalyst Design ◽  
Design Strategies ◽  
Faradaic Efficiency

AbstractFor steady electroconversion to value-added chemical products with high efficiency, electrocatalyst reconstruction during electrochemical reactions is a critical issue in catalyst design strategies. Here, we report a reconstruction-immunized catalyst system in which Cu nanoparticles are protected by a quasi-graphitic C shell. This C shell epitaxially grew on Cu with quasi-graphitic bonding via a gas–solid reaction governed by the CO (g) - CO2 (g) - C (s) equilibrium. The quasi-graphitic C shell-coated Cu was stable during the CO2 reduction reaction and provided a platform for rational material design. C2+ product selectivity could be additionally improved by doping p-block elements. These elements modulated the electronic structure of the Cu surface and its binding properties, which can affect the intermediate binding and CO dimerization barrier. B-modified Cu attained a 68.1% Faradaic efficiency for C2H4 at −0.55 V (vs RHE) and a C2H4 cathodic power conversion efficiency of 44.0%. In the case of N-modified Cu, an improved C2+ selectivity of 82.3% at a partial current density of 329.2 mA/cm2 was acquired. Quasi-graphitic C shells, which enable surface stabilization and inner element doping, can realize stable CO2-to-C2H4 conversion over 180 h and allow practical application of electrocatalysts for renewable energy conversion.

scholarly journals Recent Advances in Transition-Metal-Free (4+3)-Annulations

Synthesis ◽  
2021 ◽  
Author(s):  
Heather Lam ◽  
Mark Lautens ◽  
Xavier Abel-Snape ◽  
Martin F. Köllen
Keyword(s):  
Transition Metal ◽  
Boronic Acid ◽  
Lewis Acids ◽  
Acid Catalysis ◽  
Heterocyclic Carbenes ◽  
Bronsted Acids ◽  
Metal Free ◽  
Previous Review ◽  
Dual Activation ◽  
Metal Catalyzed

Abstract(4+3)-Annulations are incredibly versatile reactions which combine a 4-atom synthon and a 3-atom synthon to form both 7-membered carbocycles as well as heterocycles. We have previously reviewed transition-metal-catalyzed (4+3)-annulations. In this review, we will cover examples involving bases, NHCs, phosphines, Lewis and Brønsted acids as well as some rare examples of boronic acid catalysis and photocatalysis. In analogy to our previous review, we exclude annulations involving cyclic dienes like furan, pyrrole, cyclohexadiene or cyclopentadiene, as Chiu, Harmata, Fernándes and others have recently published reviews encompassing such substrates. We will however discuss the recent additions (2010–2020) to the literature on (4+3)-annulations involving other types of 4-atom-synthons.1 Introduction2 Bases3 Annulations Using N-Heterocyclic Carbenes3.1 N-Heterocyclic Carbenes (NHCs)3.2 N-Heterocyclic Carbenes and Base Dual-Activation4 Phosphines5 Acids5.1 Lewis Acids5.2 Brønsted Acids6 Boronic Acid Catalysis and Photocatalysis7 Conclusion

scholarly journals Metal-Free Living Cationic Polymerization via Carbon-Sulfur Bonds (2)

2015 ◽  
Vol 88 (12) ◽  
pp. 461-465
Author(s):  
Mineto UCHIYAMA ◽  
Kotaro SATOH ◽  
Masami KAMIGAITO
Keyword(s):  
Cationic Polymerization ◽  
Free Living ◽  
Metal Free ◽  
Living Cationic Polymerization
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