Diskrete Metallkatalysatoren zur Copolymerisation von CO₂ mit Epoxiden: Entdeckung, Reaktivität, Optimierung, Mechanismus

Abstract

Synthetische Polymere werden zum weit überwiegenden Teil aus dem Rohstoff Erdöl hergestellt und sind nicht erneuerbar. Demnach besteht ein steigender Bedarf an Herstellungsverfahren für Polymere aus erneuerbaren Quellen und ein zunehmendes Interesse an biologisch abbaubaren polymeren Materialien. Polycarbonate, die aus CO2 und Epoxiden zugänglich sind, haben das Potenzial, diese Anforderungen zu erfüllen. Seit der Entdeckung von Katalysatoren zur Copolymerisation von CO2 und Epoxiden in den späten 60er Jahren durch Inoue wurde ein erheblicher Forschungsaufwand in die Entwicklung von Katalysatoren mit verbesserter Aktivität und Selektivität investiert. Dieser Aufsatz behandelt wohldefinierte Katalysatoren für die Epoxid‐CO2‐Copolymerisation und verwandte Reaktionen.

Microstructure Analysis of a CO2 Copolymer from Styrene Oxide at the Diad Level

“…[2] Therefore, the assignment of the stereo-and/or regiochemistry information of a polymer is one of the most-important tasks in the field of stereospecific polymerization catalysis. [3,4] In the alternating copolymerization of CO 2 with terminal epoxides, [5] there are also considerations of regiochemistry of the epoxide ring-opening and stereochemistry of the carbonate unit sequence in the resulting polymer chain. [6] In 2004, Chisholm and co-workers synthesized a series of oligoether carbonates, R(PO) n OCO 2 (PO) n R (R= Me, Et, or H; PO = propylene oxide ring-opened unit; and n = 1, 2, 3, 4, 10), as potential models for the microstructural assignment of poly(propylene carbonate) chains by NMR spectroscopy (Scheme 1).…”

Differences in Reactivity of Epoxides in the Copolymerisation with Carbon Dioxide by Zinc‐Based Catalysts: Propylene Oxide versus Cyclohexene Oxide

“…[1][2][3][4] The methods to overcome the high kinetic barriers that are associated with the use of carbon dioxide for chemical synthesis are mainly based on reduction, oxidative coupling with unsaturated compounds on low valent transition-metal complexes or the nucleophilic attack on the carbonyl carbon. [3,5,6] With regard to industrial applications, the highest impact can be ascribed to the reactivity of CO 2 towards nucleophiles such as alkoxides, anionically opened epoxides and amines to give products such as salicylic acid (6 Mt CO 2 per year), cyclic carbonates (a few kt CO 2 per year; in this text, cyclic carbonate is used instead of more common designations such as propylene carbonate to distinguish the side product from polycarbonate) and urea (70 Mt CO 2 per year).…”

“…[3,5,6] With regard to industrial applications, the highest impact can be ascribed to the reactivity of CO 2 towards nucleophiles such as alkoxides, anionically opened epoxides and amines to give products such as salicylic acid (6 Mt CO 2 per year), cyclic carbonates (a few kt CO 2 per year; in this text, cyclic carbonate is used instead of more common designations such as propylene carbonate to distinguish the side product from polycarbonate) and urea (70 Mt CO 2 per year). [2,4] All of these nucleophiles are highly reactive molecules and can therefore be used to overcome the thermodynamic stability of carbon dioxide. [2,4] Beside cyclic carbonate formation, the reaction of epoxides and carbon dioxide to give copolymers has received much attention over the past 40 years.…”

Preparation, characterization and crystal structure of dinuclear zinc(II) carboxylate complex with 1-(pyridin-4-yl)ethanone and 4-methylbenzoate based ligands

“…At the same time, zinc carboxylates are attracting attention as highly active catalysts for the polymerization or copolymerization of a wide range of organic monomers [12][13][14][15].…”