Lewis acid catalysed microwave-assisted synthesis of diaryl sulfones and comparison of associated carbon dioxide emissions

Diaryl sulfones were synthesised using a variety of Lewis acid catalysts under microwave activation. Catalysts were used both homogeneously and heterogeneously (K10 montmorillonite clay). The most effective catalyst in terms of yield was found to be iron(III) chloride with a yield of 89%. Supported iron(III) chloride gave a yield of 77%. The highest selectivity to the 4,4′ isomer was obtained using supported bismuth(III) chloride. A series of other diaryl sulfones were synthesised using microwave-assisted Lewis acid catalysis in good yield. The energy used in the reactions was measured and the quantity of carbon dioxide generated per mole of product was compared using microwave and traditional thermal activation (oil bath) methods. Where yields were comparable, microwave-assisted synthesis was shown to produce substantially less carbon dioxide per mole of product.

Graphical abstractIn this publication a range of diaryl sulfones were synthesised using a variety of hetero- and homogeneous Lewis acid catalysts in good yields under microwave activation. The carbon dioxide emissions associated with the reactions were estimated to compare environmental performance in the form of a new green chemistry metric.Figure optionsDownload full-size imageDownload as PowerPoint slide