Heterogeneous catalysts for cyclic carbonate synthesis from carbon dioxide and epoxides

Abstract

This review surveys six classes of heterogeneous catalysts that have been used in the conversion of epoxides and CO2 into cyclic carbonates; metal organic frameworks (MOFs); silica-based catalysts; organic polymer supports; metal oxides; zeolites and carbon-based catalysts. Many of these catalysts are extremely active in the ring-opening of terminal epoxides, require fairly mild conditions and can be made in a sustainable manner. Some catalytic systems however require toxic and hazardous chemicals in their synthesis, and many struggle to ring-open the more sterically demanding and hindered internal epoxides. This review covers the most recent heterogeneous catalysts reported in the literature, not only from a catalytic efficiency perspective but also from a green chemistry and sustainable viewpoint.

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

“…Heterogeneous catalysts can be developed by the immobilisation of a catalytically active unit onto a solid support; by the use of a solid material that has intrinsic catalytic activity; or by combining these two approaches. 127 Heterogeneous catalysts generally have advantages associated with ease of catalyst separation and recycling and an ability to be used in flow reactors. The latter is an important consideration in cyclic carbonate synthesis, given the highly exothermic nature of the reaction (Figure 3) and the highly toxic nature of low molecular weight epoxides.…”

Covalent Organic Frameworks for Simultaneous CO2 Capture and Selective Catalytic Transformation

“…Although great progress and development have been made in heterogeneous catalysts, most of them are active only at high temperatures and high pressures. The development of an efficient heterogeneous catalyst for synthesizing cyclic carbonates under mild reaction conditions is of immense significance nowadays [31,32]. Thus, there is considerable interest to design and synthesize a material that is capable of capturing and simultaneously converting CO 2 into cyclic carbonates under mild conditions.…”

Catalytic Formation of Cyclic Carbonates using Gallium Aminotrisphenolate Compounds and Comparison to their Aluminium Congeners: A Combined Experimental and Computational Study

“…In this context, the atom efficient synthesis of cyclic carbonates from ring‐strained epoxides (high energy substrates) and CO 2 (Scheme 1a) has attracted plenty of attention, primarily as a result of their well‐established application as electrolytes in Li‐ion batteries [2] and their utility as both monomers for polycarbonate synthesis [3] and non‐isocyanate polyurethanes [4] or as synthetic intermediates [5] . Whilst a plethora of both heterogeneous [6] and homogenous catalysts [7] have been developed for this reaction over the last decade, catalysts that are truly “highly active” still remain relatively elusive. Successful homogeneous catalysts are often based on the activation of epoxide substrates through a Lewis pair interaction, arising from the use of a Lewis acid catalyst and the lone‐pair of the oxygen from the epoxide, which results in a state that facilitates the key ring‐opening of the epoxide by an external nucleophile co‐catalyst [8] .…”