Application of Green Solvents: PEG and scCO2 in the Mono- or Biphasic Catalytic Systems for the Repetitive Batch Coupling of Vinylsilanes with Vinyl Boronates toward 1-Boryl-1-silylethenes

Mechanism of catalysis with binary and triple catalytic systems based on redox inactive metal (lithium) compound {LiSt+L2} and {LiSt+L2+PhOH} (L2=DMF or HMPA), in the selective ethylbenzene oxidation by dioxygen into -phenylethyl hydroperoxide is researched. The results are compared with catalysis by nickel-lithium triple system {NiII(acac)2+LiSt+PhOH} in selective ethylbenzene oxidation to PEH. The role of H-bonding in mechanism of catalysis is discussed. The possibility of the stable supramolecular nanostructures formation on the basis of triple systems, {LiSt+L2+PhOH}, due to intermolecular H-bonds, is researched with the AFM method.

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Dual-Function, Light Switchable Cobalt Catalysis via Active Site Metamorphosis

10.26434/chemrxiv.11353106.v1 ◽

2019 ◽

Author(s):

Enrico Bergamaschi ◽

Frédéric Beltran ◽

Christopher Teskey

Keyword(s):

Visible Light ◽

Active Site ◽

Catalytic Site ◽

Dual Function ◽

Catalytic Systems ◽

Hydride Complex ◽

Dual Functional ◽

Multiple Processes ◽

Olefin Migration

Switchable catalysis offers opportunities to control the rate or selectivity of a reaction via a stimulus such as pH or light. However, few examples of switchable catalytic systems that can facilitate multiple processes exist. Here we report a rare example of such dual-functional, switchable catalysis. Featuring an easily prepared, bench-stable cobalt(I) hydride complex in conjunction with pinacolborane, we can completely alter the reaction outcome between two widely employed transformations – olefin migration and hydroboration – with visible light as the sole trigger. This dichotomy arises from ligand photodissociation which leads to metamorphosis of the active catalytic site, resulting in divergent mechanistic pathways.

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Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

10.26434/chemrxiv.12115026.v1 ◽

2020 ◽

Author(s):

Laurent Sévery ◽

Jacek Szczerbiński ◽

Mert Taskin ◽

Isik Tuncay ◽

Fernanda Brandalise Nunes ◽

...

Keyword(s):

Aqueous Media ◽

Heterogeneous Systems ◽

Catalytic Systems ◽

New Approach ◽

Molecular Systems ◽

Electrode Surfaces ◽

Catalytic Surfaces ◽

Oxide Electrodes ◽

The Stability ◽

Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

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Mapping the “Extra Solvent Power, ESP” of Ionic Liquids for Monomers, Polymers and Globular Nanoparticles

10.26434/chemrxiv.5384293.v1 ◽

2017 ◽

Author(s):

Jose A. Pomposo

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Linear Polymers ◽

Green Solvents ◽

Ionic Polymers ◽

First Time ◽

Solvent Power

Understanding the miscibility behavior of ionic liquid (IL) / monomer, IL / polymer and IL / nanoparticle mixtures is critical for the use of ILs as green solvents in polymerization processes, and to rationalize recent observations concerning the superior solubility of some proteins in ILs when compared to standard solvents. In this work, the most relevant results obtained in terms of a three-component Flory-Huggins theory concerning the “Extra Solvent Power, ESP” of ILs when compared to traditional non-ionic solvents for monomeric solutes (case I), linear polymers (case II) and globular nanoparticles (case III) are presented. Moreover, useful ESP maps are drawn for the first time for IL mixtures corresponding to case I, II and III. Finally, a potential pathway to improve the miscibility of non-ionic polymers in ILs is also proposed.

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Nickel-Catalyzed Inter- and Intramolecular Carbon-Sulfur Bond Metathesis by Reversible Arylation

10.26434/chemrxiv.8168180.v1 ◽

2019 ◽

Author(s):

Tristan Delcaillau ◽

Alessandro Bismuto ◽

Zhong Lian ◽

Bill Morandi

Keyword(s):

Good Yield ◽

Functional Group ◽

Product Formation ◽

Single Bond ◽

Ring Closing Metathesis ◽

Catalytic Systems ◽

Metathesis Reactions ◽

New Applications ◽

Further Development ◽

Sulfur Bond

A nickel-catalyzed carbon-sulfur bond metathesis has been developed to access high-value thioethers. 1,2-bis(dicyclohexylphosphino)ethane (dcype) is essential to promote this highly functional group tolerant reaction. Further, synthetically challenging macrocycles could be obtained in good yield in an unusual example of ring-closing metathesis which does not involve alkene bonds. In-depth organometallic studies support a reversible Ni(0)-Ni(II) pathway to product formation. Overall, this work does not only disclose a more sustainable and more functional group tolerant alternative to previous catalytic systems based on Pd, but also presents new applications and mechanistic information which are highly relevant to the further development and application of unusual single bond metathesis reactions.

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Ionic Liquids for Topical Delivery in Cancer

Current Medicinal Chemistry ◽

10.2174/0929867325666181026110227 ◽

2020 ◽

Vol 26 (41) ◽

pp. 7520-7532 ◽

Cited By ~ 4

Author(s):

Ana Rita Dias ◽

João Costa-Rodrigues ◽

Cátia Teixeira ◽

Cristina Prudêncio ◽

Paula Gomes ◽

...

Keyword(s):

Ionic Liquids ◽

Clinical Applications ◽

Great Promise ◽

Topical Drug Delivery ◽

Green Solvents ◽

2Nd Generation ◽

Windows Of Opportunity ◽

Pharmaceutical Technology ◽

Skin Cancers ◽

Per Se

: The unique properties of ionic liquids make them quite appealing for diverse applications, from “green” solvents (1st generation ionic liquids) to finely tuned materials (2nd generation ionic liquids). A decade ago, a 3rd generation of ionic liquids emerged which is focused on their prospective clinical applications, either as drugs per se or as adjuvants in drug formulations. In recent years, research focused on the use of ionic liquids for topical drug delivery has been increasing and holds great promise towards clinical application against skin cancers. This article highlights the growing relevance of ionic liquids in medicinal chemistry and pharmaceutical technology, which is opening new windows of opportunity.

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Palladium Promoted Copolymerization of Carbon Monoxide with Polar or Nonpolar Olefinic Monomers

Current Organic Chemistry ◽

10.2174/1385272824999201102221113 ◽

2020 ◽

Vol 24 ◽

Author(s):

Yanlin Zong ◽

Qiankun Li ◽

Hongliang Mu ◽

Zhongbao Jian

Keyword(s):

Carbon Monoxide ◽

Physical Properties ◽

Vinyl Monomers ◽

Pd Catalysts ◽

Catalytic Systems

Abstract:: The copolymers of carbon monoxide (CO) and olefins, namely polyketones, are a family of widely used materi-als. In the catalytic preparation of these materials, palladium(II) catalysts represent the most successful catalytic systems. The production of both alternating and non-alternating polyketones has been achieved, with great difference in their physical properties. Herein, a variety of palladium(II) catalysts employed for the copolymerization of CO with various olefinic mon-omers such as ethylene, α-olefins, styrene and polar vinyl monomers are fully summarized. The influence of important fac-tors such as solvents and counterions on specific copolymerization, is also discussed. This review aims to enlighten the de-sign of new Pd catalysts with improved properties, as well as the development of new polyketone materials.

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Green Solvents in Organic Synthesis: An Overview II

Current Organic Chemistry ◽

10.2174/1385272820666160209212804 ◽

2016 ◽

Vol 20 (15) ◽

pp. 1576-1583 ◽

Cited By ~ 6

Author(s):

Karem Shanab ◽

Catharina Neudorfer ◽

Helmut Spreitzer

Keyword(s):

Organic Synthesis ◽

Green Solvents

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