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16 pages, 7283 KiB

Open AccessFeature PaperArticle

Investigation and Comparison of Catalytic Methods to Produce Green CO₂-Containing Monomers for Polycarbonates

by Daniel Christian Brüggemann, Philipp Harry Isbrücker, Dzenna Zukova, Franz Robert Otto Heinrich Schröter, Yen Hoang Le and Reinhard Schomäcker

Catalysts 2024, 14(6), 362; https://doi.org/10.3390/catal14060362 - 1 Jun 2024

Viewed by 1863

Abstract

The preparation of CO₂-containing polymers with improved degradation properties is still very challenging. An elegant method for preparing these polymers is to use CO₂-containing monomers in ring-opening polymerizations (ROP) which are particularly gentle and energy-saving methods. However, cyclic carbonates are required for this which are not readily available. This paper therefore aims to present the optimization and comparison of two synthesis methods to obtain cyclic carbonates for ROP. Within this work, cyclic styrene carbonate was synthesized from readily available raw materials by using a Jacobsen catalyst for the reaction of styrene oxide and carbon dioxide or an organocatalyst for the transesterification of methyl carbonate with 1-phenyl-1,2-ethanediol. The latter performed with 100% selectivity to the desired styrene carbonate, which was succesfully tested in ROP, producing an amorphous thermoplastic polymer with a T_G of 185 °C. Full article

(This article belongs to the Topic Carbon Dioxide Capture or Removal and Valorisation: Advances in the Development of Materials and Technologies)

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12 pages, 1050 KiB

Open AccessArticle

Electrochemical Epoxidation Catalyzed by Manganese Salen Complex and Carbonate with Boron-Doped Diamond Electrode

by Pijush Kanti Roy, Keisuke Amanai, Ryosuke Shimizu, Masahito Kodera, Takuya Kurahashi, Kenji Kitayama and Yutaka Hitomi

Molecules 2023, 28(4), 1797; https://doi.org/10.3390/molecules28041797 - 14 Feb 2023

Cited by 6 | Viewed by 3513

Abstract

Epoxides are essential precursors for epoxy resins and other chemical products. In this study, we investigated whether electrochemically oxidizing carbonate ions could produce percarbonate to promote an epoxidation reaction in the presence of appropriate metal catalysts, although Tanaka and co-workers had already completed a separate study in which the electrochemical oxidation of chloride ions was used to produce hypochlorite ions for electrochemical epoxidation. We found that epoxides could be obtained from styrene derivatives in the presence of metal complexes, including manganese(III) and oxidovanadium(IV) porphyrin complexes and manganese salen complexes, using a boron-doped diamond as the anode. After considering various complexes as potential catalysts, we found that manganese salen complexes showed better performance in terms of epoxide yield. Furthermore, the substituent effect of the manganese salen complex was also investigated, and it was found that the highest epoxide yields were obtained when Jacobsen’s catalyst was used. Although there is still room for improving the yields, this study has shown that the in situ electrochemical generation of percarbonate ions is a promising method for the electrochemical epoxidation of alkenes. Full article

(This article belongs to the Special Issue Design Strategies for Metal Complexes that Activate Bio-Related Small Molecules)

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16 pages, 4264 KiB

Open AccessArticle

Chiral Mn^III (Salen) Immobilized on Organic Polymer/Inorganic Zirconium Hydrogen Phosphate Functionalized with 3-Aminopropyltrimethoxysilane as an Efficient and Recyclable Catalyst for Enantioselective Epoxidation of Styrene

by Xiaochuan Zou, Yue Wang, Cun Wang, Kaiyun Shi, Yanrong Ren and Xin Zhao

Polymers 2019, 11(2), 212; https://doi.org/10.3390/polym11020212 - 26 Jan 2019

Cited by 8 | Viewed by 3734

Abstract

Organic polymers/inorganic zirconium hydrogen phosphate (ZSPP, ZPS-IPPA, and ZPS-PVPA) functionalized with 3-aminopropyltrimethoxysilane were prepared and used to support chiral Mn^III (salen) complexes (Jacobsen’s catalyst). Different characterization methods demonstrated that the chiral Mn^III (salen) complexes was successfully supported on the surface of the carrier (ZSPP, ZPS-IPPA, or ZPS-PVPA) through a 3-aminopropyltrimethoxysilane group spacer. The supported catalysts effectively catalyzed epoxidation of styrene with m-chloroperbenzoic acid (m-CPBA) as an oxidant in the presence of N-methylmorpholine N-oxide (NMO) as an axial base. These results (ee%, 53.3–63.9) were significantly better than those achieved under a homogeneous counterpart (ee%, 46.2). Moreover, it is obvious that there was no significant decrease in catalytic activity after the catalyst 3 was recycled four times (cons%: from 95.0 to 92.6; ee%: from 64.7 to 60.1). Further recycles of catalyst 3 resulted in poor conversions, although the enantioselectivity obtained was still higher than that of corresponding homogeneous catalyst even after eight times. After the end of the eighth reaction, the solid catalyst was allowed to stand in 2 mol/L of dilute hydrochloric acid overnight, prompting an unexpected discovery that the catalytic activity of the catalyst was recovered again at the 9th and 10th cycles of the catalyst. Full article

(This article belongs to the Special Issue Polymerizations Promoted by Metal Complexes)

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9 pages, 1491 KiB

Open AccessCommunication

(Salen)Mn(III) Catalyzed Asymmetric Epoxidation Reactions by Hydrogen Peroxide in Water: A Green Protocol

by Francesco Paolo Ballistreri, Chiara M. A. Gangemi, Andrea Pappalardo, Gaetano A. Tomaselli, Rosa Maria Toscano and Giuseppe Trusso Sfrazzetto

Int. J. Mol. Sci. 2016, 17(7), 1112; https://doi.org/10.3390/ijms17071112 - 12 Jul 2016

Cited by 30 | Viewed by 7142

Abstract

Enantioselective epoxidation reactions of some chosen reactive alkenes by a chiral Mn(III) salen catalyst were performed in H₂O employing H₂O₂ as oxidant and diethyltetradecylamine N-oxide (AOE-14) as surfactant. This procedure represents an environmentally benign protocol which leads [...] Read more.

(This article belongs to the Special Issue Chemical Bond and Bonding 2016)

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22 pages, 290 KiB

Open AccessArticle

Synthesis of Chiral Building Blocks for Use in Drug Discovery

by Sharon T. Marino, Danuta Stachurska-Buczek, Daniel A. Huggins, Beata M. Krywult, Craig S. Sheehan, Thao Nguyen, Neil Choi, Jack G. Parsons, Peter G. Griffiths, Ian W. James, Andrew M. Bray, Jonathan M. White and Rustum S. Boyce

Molecules 2004, 9(6), 405-426; https://doi.org/10.3390/90600405 - 31 May 2004

Cited by 28 | Viewed by 17606

Abstract

In the past decade there has been a significant growth in the sales of pharmaceutical drugs worldwide, but more importantly there has been a dramatic growth in the sales of single enantiomer drugs. The pharmaceutical industry has a rising demand for chiral intermediates and research reagents because of the continuing imperative to improve drug efficacy. This in turn impacts on researchers involved in preclinical discovery work. Besides traditional chiral pool and resolution of racemates as sources of chiral building blocks, many new synthetic methods including a great variety of catalytic reactions have been developed which facilitate the production of complex chiral drug candidates for clinical trials. The most ambitious technique is to synthesise homochiral compounds from non-chiral starting materials using chiral metal catalysts and related chemistry. Examples of the synthesis of chiral building blocks from achiral materials utilizing asymmetric hydrogenation and asymmetric epoxidation are presented. Full article

(This article belongs to the Special Issue RACI 2003 symposium)

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