Synthesis and high-throughput testing of multilayered supported ionic liquid catalysts for the conversion of CO₂ and epoxides into cyclic carbonates

Abstract

Multilayered covalently supported ionic liquid phase (mlc-SILP) materials were synthesised by grafting\ud different bis-vinylimidazolium salts on thiol-functionalised silica. These materials, which contain a crosslinked\ud oligomeric network of imidazolium units, were characterised and tested as catalysts for the reaction\ud of carbon dioxide with various epoxides to produce cyclic carbonates. The materials prepared by\ud supporting a bis-imidazolium iodide salt with xylene or octane as a linker between the imidazolium\ud units were identified as the most active catalysts and displayed high turnover numbers and improved\ud productivity compared to known supported ionic liquid catalysts. The most promising mlc-SILP catalysts\ud were further studied to tune the reaction conditions towards optimum catalytic performance and to\ud investigate their versatility with different substrates and their reusability. The rapid and parallel screening\ud of the catalysts was efficiently carried out by means of high-throughput (HT) experimentation

Imidazolium-based silica microreactors for the efficient conversion of carbon dioxide

“…The Brunauer-Emmet-Teller (BET) specific surface area (180 m 2 /g) as well as the absence of a narrow pore size distribution obtained for the SImCat, can be attributed to the presence of the organic polymeric matrix inside the solid. The observed BET value is similar to those reported for other porous 60 silica architectures covered by polymeric cross-linked organic shell9,10, 13,17,41, 65 . The type 3 hysteresis loop observed at high P/P 0 can be ascribed to a large meso-macro porosity arising from interparticles interaction.…”

“…The first catalytic test was 45 performed selecting the initial pressure of 50 bar. It is worth to underline that the TON value obtained under these conditions (TON = 136) is one of the highest reported in literature for supported heterogeneous systems 9 . An increase of the working pressure to 70 bar, while keeping constant the temperature at 150 50 °C (Table 1, entry 2), did not substantially improve the catalytic performances.…”

Adamantylated trisimidazolium-based tritopic guests and their binding properties towards cucurbit[7]uril and β-cyclodextrin

“…Cationic moieties are frequently based on alkylammonium, pyridinium or imidazolium salts. However, imidazolium salts have some additional advantages as they display catalytic activity [43][44][45][46][47] and an ability to be transformed into N-heterocyclic carbenes to coordinate metals [48][49][50][51][52][53].…”

Advances in Organic and Organic-Inorganic Hybrid Polymeric Supports for Catalytic Applications

“…The materials 20b and 21b, having octane and p-xylene as linker, respectively, and iodide as counterion, were identified as the most active catalysts. These results indicated that the leaving ability of the halide played a role in determining the reaction rate and that a better separation between the imidazolium units, obtained with the linker with the longest chain (octane), could prove favourable In 2014, a series of multilayered covalently-supported ionic liquid phase (mlc-SILP) materials 18, 19a-b, 20a-b, 21a-b were synthesised by grafting different bis-vinylimidazolium salts on thiol-functionalised silica (Scheme 9) [17]. Covalently-supported imidazolium salts represent an interesting class of recyclable catalysts with excellent stability and durability [18,19].…”

“…Finally, the catalytic activity of Poly(mVIm + I − ) was very low, despite the higher concentration of active sites, as a consequence of the absence of porosity and then of the low accessibility to the active sites. In 2014, a series of multilayered covalently-supported ionic liquid phase (mlc-SILP) materials 18, 19a-b, 20a-b, 21a-b were synthesised by grafting different bis-vinylimidazolium salts on thiolfunctionalised silica (Scheme 9) [17]. Covalently-supported imidazolium salts represent an interesting class of recyclable catalysts with excellent stability and durability [18,19].…”