Multivalent Bifunctional Carbosilane Dendrimer Supported Ammonium and Phosphonium Organocatalysts for the Coupling of CO2 and Epoxides.

0531168 - ÚCHP 2021 RIV US eng J - Journal Article
Červenková Šťastná, Lucie - Krupková, Alena - Petričkovič, Roman - Müllerová, Monika - Matoušek, J. - Koštejn, Martin - Cuřínová, Petra - Jandová, Věra - Šabata, Stanislav - Strašák, Tomáš
Multivalent Bifunctional Carbosilane Dendrimer Supported Ammonium and Phosphonium Organocatalysts for the Coupling of CO2 and Epoxides.
ACS Sustainable Chemistry & Engineering. Roč. 8, č. 31 (2020), s. 11692-11703. ISSN 2168-0485. E-ISSN 2168-0485
R&D Projects: GA ČR(CZ) GC19-23760J
Institutional support: RVO:67985858
Keywords : polycationic carbosilane dendrimers * dendritic ionic liquids * chemical fixation of CO2
OECD category: Organic chemistry
Impact factor: 8.198, year: 2020
Method of publishing: Open access with time embargo

Insertion of carbon dioxide into structure of organic epoxides leads to a formation of valuable cyclic carbonates and polycarbonates. For the purpose of this process, we report here a series of recyclable organocatalysts with superior activity. Carbosilane dendrimers (1st to 3rd generation) are employed as a support to which periphery ammonium or phosphonium centers are covalently attached to form a dendritic ionic liquid (DIL). Obtained DILs were tested as homogeneous catalysts in cycloaddition of CO2 to epoxides with respect to their activity and recyclability. The catalytic performance of active sites is enhanced by the presence of proximal hydroxyl group, playing the role of hydrogen bond donor. Experimentally observed synergistic effect was confirmed by Density Functional Theory (DFT) calculations. The activity of DILs is affected more by the structure of onium salt than by the size of support (dendrimer generation). Dendritic catalysts of all tested generations could be recovered by nanofiltration and repeatedly reused. In order to simplify the separation of the catalysts, composite materials were prepared by intercalating the more active ammonium dendrimers into the interlayer space of natural montmorillonite. Resulting heterogeneous catalysts were easily separable by centrifugation, while retaining reasonable level of activity.
Permanent Link: http://hdl.handle.net/11104/0310792