Recent developments in organocatalysed transformations of epoxides and carbon dioxide into cyclic carbonates

Abstract

The synthesis of cyclic carbonates from epoxides and carbon dioxide using metal-free catalyst systems is critically reviewed.

Guanidyl-implanted UiO-66 as an efficient catalyst for the enhanced conversion of carbon dioxide into cyclic carbonates

“…Compared with only TBAB, the UiO-66-Gua 0.2 ( s )/TBAB catalyst showed enhanced performance in the ECH cycloaddition, especially after 4 h. This might be attributed to the synergistic effect of UiO-66-Gua 0.2 ( s ) and the Br − ions during the coupling reaction between CO 2 and the epoxide. 10,47 In addition, the ECH cycloaddition catalyzed by UiO-66-Gua 0.2 ( s )/TBAB was found to follow the pseudo-first-order reaction with the observed rate constant of 0.14 h −1 (Fig. S17†), which matched with most of the active heterocatalysts.…”

“…These catalysts usually feature site-specific functional groups that are capable of stabilizing key intermediates during the reaction between epoxides and CO 2 . 10 Homogeneous catalysts generally show intrinsic merits such as well-defined chemical structures, high efficiency, and easy-to-explore structure–function relationships. However, the major disadvantage of homogeneous catalysts is the difficulty in separating them from the reaction solution and poor recyclability.…”

Fabrication of a hollow sphere N,S co-doped bifunctional carbon catalyst for sustainable fixation of CO2 to cyclic carbonates

“…To date, a variety of homogeneous and heterogeneous catalytic systems have been reported for cycloaddition reactions with CO 2 and epoxide, including alkali metal salts, ionic liquids, quaternary ammonium or phosphonium salts, crown ether, organocatalysts, organometallic complexes, porphyrin, metal–salen complexes, metal oxides, zeolites, metal–organic frameworks (MOFs), porous organic framework (POFs), functional carbon nitride, functionalized silica, and so on. 21–29 Generally, homogeneous catalysts stand out as the most effective and tailor-made catalysts for cycloaddition reactions, but their intrinsic problems such as troublesome separation, purification, and regeneration restrict their commercialization. In this context, heterogeneous catalysts are gaining attention from scientists and industrialists as they are task-specific and readily separated and regenerated.…”

Chromium-Salophen as a Soluble or Silica-Supported Co-Catalyst for the Fixation of CO2 Onto Styrene Oxide at Low Temperatures

“…It is noteworthy that this particular reaction requires the use of organocatalysts (Guo et al, 2021), generally quaternary ammonium salts, but the addition of metal complexes or salts as well as hydrogen bond donors acting as Lewis acids (co-catalysts) (Kim et al, 2013;Adhikari et al, 2014;Supasitmongkol and Styring, 2014;Wang et al, 2014;Sharma et al, 2018;Rehman et al, 2021;Zhou et al, 2021), allowing the activation of epoxides, is a strategy often implemented (Darensbourg and Holtcamp, 1996;Laugel et al, 2013;He et al 2014;Comerford et al, 2015;Claver et al, 2020). Among the various cocatalysts used, transition metal complexes with Schiff-base ligands (salen or salophen) represent a particularly attractive class of compounds due to their ease of synthesis and the large variety of metal centres that can be incorporated within their N 2 O 2 coordination sphere (Yoon and Jacobsen, 2003;Cozzi, 2004;Gupta and Sutar, 2008;Decortes et al, 2010).…”