Ti(IV)–Tris(phenolate) Catalyst Systems for the Ring-Opening Copolymerization of Cyclohexene Oxide and Carbon Dioxide
| Autor: | Leticia Peña Carrodeguas, Ryan W. F. Kerr, Natalia V Reis, Sumesh K. Raman, Charlotte K. Williams, Andreas Phanopoulos, Arron C. Deacy, Sebastian Morton, Matthew G. Davidson |
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| Rok vydání: | 2020 |
| Předmět: |
Chemistry
Organic chemistry.chemical_element 010402 general chemistry Ring (chemistry) 0305 Organic Chemistry 01 natural sciences Chloride Article Catalysis ZIRCONIUM Inorganic Chemistry chemistry.chemical_compound 0399 Other Chemical Sciences Polymer chemistry 0302 Inorganic Chemistry Copolymer medicine Chemistry Inorganic & Nuclear Physical and Theoretical Chemistry Triphenylphosphine ALTERNATING COPOLYMERIZATION GROUP-4 COMPLEXES Science & Technology TRIANIONIC AMINE 010405 organic chemistry Organic Chemistry Iminium 0104 chemical sciences Chemistry POLYMERIZATION chemistry TITANIUM Physical Sciences METAL-COMPLEXES ALKOXIDE INITIATORS CO2 EPOXIDES Cyclohexene oxide medicine.drug Titanium |
| Zdroj: | Organometallics |
| ISSN: | 1520-6041 0276-7333 |
| DOI: | 10.1021/acs.organomet.9b00845 |
| Popis: | Titanium(IV) complexes of amino-tris(phenolate) ligands (LTiX, X = chloride, isopropoxide) together with bis(triphenylphosphine)iminium chloride (PPNCl) are active catalyst systems for the ring-opening copolymerization of carbon dioxide and cyclohexene oxide. They show moderate activity, with turnover frequency values of ∼60 h–1(0.02 mol % of catalyst, 80 °C, 40 bar of CO2) and high selectivity (carbonate linkages >90%), but their absolute performances are lower than those of the most active Ti(IV) catalyst systems. The reactions proceed with linear evolution of polycarbonate (PCHC) molar mass with epoxide conversion, consistent with controlled polymerizations, and evolve bimodal molar mass distributions of PCHC (up toMn= 42 kg mol–1). The stoichiometric reaction between [LTiOiPr] and tetraphenylphosphonium chloride, PPh4Cl, allows isolation of the putative catalytic intermediate [LTi(OiPr)Cl]−, which is characterized using single-crystal X-ray diffraction techniques. The anionic titanium complex [LTi(OR)Cl]−is proposed as a model for the propagating alkoxide intermediates in the catalytic cycle. |
| Databáze: | OpenAIRE |
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