Synthesis of cyclic carbonates from epoxides and carbon dioxide using bimetallic aluminum(salen) complexes

Abstract

Over the last six years, highly active catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide have been developed. Initial studies showed that bimetallic aluminium(salen) complexes [Al(salen)] 2 O formed active catalysts and kinetic studies allowed the catalytic cycle to be determined. The catalysts could be immobilized on silica, allowing them to be used in a gas phase flow reactor as well as in batch reactors. The compatibility of the catalysts with waste carbon dioxide present in power station flue gas has been investigated and studies to enhance the commercial applicability of the catalysts by reducing the cost of their production carried out.

Non-isocyanate polyurethanes: from chemistry to applications

“…In addition, some well-defined homogeneous metal complexes have been reported to be highly active and selective catalysts. These include aluminum salen, 35 discrete zinc phenoxides, b-diminate zinc alkoxides and chromium salen catalysts, and especially binary or bifunctional catalyst systems based on cobalt(III) complexes are reported to be very efficient catalysts at lower temperature. 36,37 An organo tin based tetralkylphosphonium halide complex was also used to achieve about 90-100% conversion.…”

Synthesis of cyclic carbonates catalysed by aluminium heteroscorpionate complexes

“…Our previous work 23 started with the synthesis of bimetallic aluminium(salen) complex 4 (Fig. 1) and the demonstration that, in the presence of a tetrabutylammonium bromide cocatalyst, it would catalyse the synthesis of cyclic carbonates from terminal epoxides and carbon dioxide at ambient temperature and pressure.…”

Development of a Halide‐Free Aluminium‐Based Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide

“…[10] We previously studied qualitatively the influence of temperature (25-100 8C) and pressure (1-10 bar) on cyclic carbonate synthesis catalysed by bimetallic aluminium complexes such as 4 and tetrabutylammonium bromide. [11] Here, we report the results of a detailed kinetic study of the synthesis of glycerol carbonate 3 g at temperatures of 25-100 8C and carbon dioxide pressures of 1-100 bar using a combination of complex 4 and tetrabutylammonium bromide as catalyst which have given new insights into the reaction pathway and led to the discovery that complex 4 can catalyse the reaction without a co-catalyst.…”

“…[12] A second series of kinetic studies was then carried out to determine the influence of the carbon dioxide, complex 4 and tetrabutylammonium bromide concentrations on the rate of reaction. Based on our previous work, [10] the rate equation was initially assumed to have the general form shown in Equation (1). Since the reactions were carried out using a large excess of carbon dioxide and the concentrations of complex 4 and tetrabutylammonium bromide do not change during the reaction, Equation (1) can be rewritten as Equation (2).…”