Catalytic methods for chemical recycling or upcycling of commercial polymers

Materials Horizons, Journal Year: 2020, Volume and Issue: 8(4), P. 1084 - 1129

Published: Dec. 23, 2020

A review covering catalytic method development to enable efficient chemical recycling and upcycling of the most abundant commercial polymers.

Language: Английский

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Homogeneous manganese-catalyzed hydrogenation and dehydrogenation reactions

Chem, Journal Year: 2020, Volume and Issue: 7(5), P. 1180 - 1223

Published: Dec. 9, 2020

Language: Английский

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Recent Progress in the Chemical Upcycling of Plastic Wastes

ChemSusChem, Journal Year: 2021, Volume and Issue: 14(19), P. 4137 - 4151

Published: May 18, 2021

The massive generation of plastic wastes without satisfactory treatment has induced severe environmental problems and gained increasing attentions. In this Minireview, recent progresses in the chemical upcycling by using various methods (mainly past three to five years) is summarized. points out a "plastic-based refinery" concept, which use as platform feedstocks produce highly valuable monomeric or oligomeric compounds, putting back into circular economy. different upcycle wastes, including hydrogenolysis, photocatalysis, pyrolysis, solvolysis, others, are introduced each section valorize diverse value-added chemicals, materials, fuels. addition, other emerging technologies well new thermosets covered.

Language: Английский

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Hydrogenative Depolymerization of Nylons

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(33), P. 14267 - 14275

Published: July 24, 2020

The widespread crisis of plastic pollution demands discovery new and sustainable approaches to degrade robust plastics such as nylons. Using a green approach based on hydrogenation, in the presence ruthenium pincer catalyst at 150 °C 70 bar H2, we report here first example hydrogenative depolymerization conventional, widely used nylons polyamides, general. Under same catalytic conditions, also demonstrate hydrogenation polyurethane produce diol, diamine, methanol. Additionally, an where monomers (and oligomers) obtained from process can be dehydrogenated back poly(oligo)amide approximately similar molecular weight, thus completing closed loop cycle for recycling polyamides. Based experimental density functional theory studies, propose that is facilitated by metal–ligand cooperativity. Overall, this unprecedented transformation, albeit proof concept level, offers toward cleaner route

Language: Английский

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Manganese-catalyzed hydrogenation, dehydrogenation, and hydroelementation reactions

Chemical Society Reviews, Journal Year: 2022, Volume and Issue: 51(11), P. 4386 - 4464

Published: Jan. 1, 2022

The emerging field of organometallic catalysis has shifted towards research on Earth-abundant transition metals due to their ready availability, economic advantage, and novel properties. In this case, manganese, the third most abundant transition-metal in Earth's crust, emerged as one leading competitors. Accordingly, a large number molecularly-defined Mn-complexes been synthesized employed for hydrogenation, dehydrogenation, hydroelementation reactions. regard, catalyst design is based three pillars, namely, metal-ligand bifunctionality, ligand hemilability, redox activity. Indeed, developed catalysts not only differ chelating atoms they possess but also working principles, thereby different turnover numbers product molecules. Hence, critical assessment molecularly defined manganese terms atoms, reaction conditions, mechanistic pathway, significant. Herein, we analyze complexes catalytic activity, versatility allow multiple transformations routes convert substrates target This article will be helpful get significant insight into design, aiding design.

Language: Английский

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Metal-catalyzed plastic depolymerization

Cell Reports Physical Science, Journal Year: 2023, Volume and Issue: 4(5), P. 101341 - 101341

Published: March 29, 2023

Polymers have become an indispensable part of our daily lives, and today we produce around 370 MT plastic per year. Only about 20% it is being recycled, the rest, 80%, unleashed into environment without appropriate treatment. This calls forth evaluation strategies available for mitigating menace "after-use" waste. Various approaches evolved over a decade are at different levels development. Plastic depolymerization upcycling considered some most prominent long-term solutions. The metal-catalyzed waste to chemical feedstocks has emerged as one promising ways address global pollution. Therefore, this review aims examine methods, notify recent progress, pinpoint current gaps, gauge potential strategy. Both homogeneous heterogeneous catalysts been reported depolymerize various polymers last decade. Considerable advances in metal-mediated polyolefins, polyesters, polycarbonates, polyurethanes, polyamides, polyethers. above produces monomers or intermediates, which can be used again polymerization thus brings back circularity. overview debates usage high temperatures, sophisticated ligands, expensive metals, stoichiometric reagents, etc., depolymerization. Thus, summarizes understanding fundamental science depolymerization, remaining scientific challenges, opportunities.

Language: Английский

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Mechanistic Studies of Hydride Transfer to Imines from a Highly Active and Chemoselective Manganate Catalyst

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(29), P. 11677 - 11685

Published: June 28, 2019

We introduce a highly active and chemoselective manganese catalyst for the hydrogenation of imines. The has large scope, can reduce aldimines ketimines, tolerates variety functional groups, among them sensitive examples such as an olefin, ketone, nitriles, nitro aryl iodo substituent or benzyl ether. could investigate transfer step between imines hydride complex in detail. found that double deprotonation ligand is essential excess base does not lead to higher rate step. identified actual K–Mn-bimetallic species obtain structure K–Mn formed after by X-ray analysis. NMR experiments indicate well-defined reaction, which first order imine, bimetallic (K–Mn) hydride, independent from concentration potassium base. propose outer-sphere mechanism protons do seem be involved rate-determining step, leading transiently negatively charged nitrogen atom substrate reacts rapidly with HOtBu (2-methylpropan-2-ol) produce amine. This based on several observations, no dependency reaction concentration, observable amide complex, high constant conducted Hammett study. Furthermore, hydrogen catalytic cycle was experimentally probed monitored subsequent quantitative regeneration H2.

Language: Английский

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Manganese‐Catalyzed Asymmetric Hydrogenation of Quinolines Enabled by π–π Interaction**

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 60(10), P. 5108 - 5113

Published: Nov. 26, 2020

Abstract The non‐noble metal‐catalyzed asymmetric hydrogenation of N‐heteroaromatics, quinolines, is reported. A new chiral pincer manganese catalyst showed outstanding catalytic activity in the affording high yields and enantioselectivities (up to 97 % ee). turnover number 3840 was reached at a low loading (S/C=4000), which competitive with most effective noble metal catalysts for this reaction. precise regulation enantioselectivity were ensured by π–π interaction.

Language: Английский

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Unmasking the Ligand Effect in Manganese-Catalyzed Hydrogenation: Mechanistic Insight and Catalytic Application

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(43), P. 17337 - 17349

Published: Oct. 21, 2019

Manganese-catalyzed hydrogenation reactions have attracted broad interest since the first report in 2016. Among reported catalytic systems, Mn catalysts supported by tridentate PNP- and NNP-pincer ligands most commonly been used. For example, a number of PNP-Mn pincer for aldehydes, aldimines, ketones, nitriles, esters. Furthermore, various NNP-Mn shown to be active less-reactive substrates such as amides, carbonates, carbamates, urea derivations. These observations indicated that exhibit higher reactivity than their PNP counterparts. Such ligand effect Mn-catalyzed has yet confirmed. Herein, we investigated origin applicability this effect. A combination experimental theoretical investigations showed on complexes were more electron-rich less sterically hindered counterparts, leading series reactions. Inspired hydrogenations, developed N-heterocycles. Specifically, hydrogenated N-heterocycles (32 examples) with up 99% yields, corresponding afforded low under same conditions. This verified is generally applicable both carbonyl noncarbonyl based catalysis.

Language: Английский

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Catalytic Hydrogenation of Cyclic Carbonates using Manganese Complexes

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(41), P. 13449 - 13453

Published: Aug. 22, 2018

Catalytic hydrogenation of cyclic carbonates to diols and methanol was achieved using a molecular catalyst based on earth-abundant manganese. The complex [Mn(CO)

Language: Английский

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