Ti(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide
<p>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, wi...
| Main Authors: | , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
American Chemical Society
2020
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| _version_ | 1797057163966808064 |
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| author | Raman, SK Deacy, AC Pena Carrodeguas, L Reis, NV Kerr, RWF Phanopoulos, A Morton, S Davidson, MG Williams, CK |
| author_facet | Raman, SK Deacy, AC Pena Carrodeguas, L Reis, NV Kerr, RWF Phanopoulos, A Morton, S Davidson, MG Williams, CK |
| author_sort | Raman, SK |
| collection | OXFORD |
| description | <p>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<sup>–1</sup> (0.02 mol % of catalyst, 80 °C, 40 bar of CO<sub>2</sub>) 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 to <em>M</em><sub>n</sub> = 42 kg mol<sup>–1</sup>). The stoichiometric reaction between [LTiO<sup><em>i</em></sup>Pr] and tetraphenylphosphonium chloride, PPh<sub>4</sub>Cl, allows isolation of the putative catalytic intermediate [LTi(O<sup><em>i</em></sup>Pr)Cl]<sup>−</sup>, which is characterized using single-crystal X-ray diffraction techniques. The anionic titanium complex [LTi(OR)Cl]<sup>−</sup> is proposed as a model for the propagating alkoxide intermediates in the catalytic cycle.</p> |
| first_indexed | 2024-03-06T19:32:21Z |
| format | Journal article |
| id | oxford-uuid:1de31076-f42d-474f-a49f-f62cc97603c7 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T19:32:21Z |
| publishDate | 2020 |
| publisher | American Chemical Society |
| record_format | dspace |
| spelling | oxford-uuid:1de31076-f42d-474f-a49f-f62cc97603c72022-03-26T11:13:29ZTi(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxideJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:1de31076-f42d-474f-a49f-f62cc97603c7EnglishSymplectic ElementsAmerican Chemical Society2020Raman, SKDeacy, ACPena Carrodeguas, LReis, NVKerr, RWFPhanopoulos, AMorton, SDavidson, MGWilliams, CK<p>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<sup>–1</sup> (0.02 mol % of catalyst, 80 °C, 40 bar of CO<sub>2</sub>) 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 to <em>M</em><sub>n</sub> = 42 kg mol<sup>–1</sup>). The stoichiometric reaction between [LTiO<sup><em>i</em></sup>Pr] and tetraphenylphosphonium chloride, PPh<sub>4</sub>Cl, allows isolation of the putative catalytic intermediate [LTi(O<sup><em>i</em></sup>Pr)Cl]<sup>−</sup>, which is characterized using single-crystal X-ray diffraction techniques. The anionic titanium complex [LTi(OR)Cl]<sup>−</sup> is proposed as a model for the propagating alkoxide intermediates in the catalytic cycle.</p> |
| spellingShingle | Raman, SK Deacy, AC Pena Carrodeguas, L Reis, NV Kerr, RWF Phanopoulos, A Morton, S Davidson, MG Williams, CK Ti(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide |
| title | Ti(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide |
| title_full | Ti(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide |
| title_fullStr | Ti(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide |
| title_full_unstemmed | Ti(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide |
| title_short | Ti(IV)–tris(phenolate) catalyst systems for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide |
| title_sort | ti iv tris phenolate catalyst systems for the ring opening copolymerization of cyclohexene oxide and carbon dioxide |
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