Novel iota carrageenan-based RhCl3 as an efficient and recyclable catalyst in Suzuki cross coupling

Abstract

RhCl3 was heterogenized into renewable polysaccharide supports, and the effect of polysaccharide type on the new catalyst performances in a Suzuki cross-coupling reaction was studied. The conversion of the fresh iota carrageenan heterogeneous system (ἰ-RhCl3), was found to be the highest, whereas it was lower than the conversion of its homogeneous analogue. In addition, the ἰ-RhCl3 (catalyst loading of 6.5 % wt) was proven to be efficient heterogeneous catalyst that was easily recycled, whereas the conversion was increased in the first and second cycles. Scanning electronic microscopy (SEM) combining Energy dispersive X-ray spectrometry and Surface analysis by X-ray photoelectron spectroscopy were performed, confirming that RhCl3 was embedded within the ἰ-carrageenan. The Fourier-transform infrared spectrometry of the heterogeneous ἰ-RhCl3 catalyst was compared to that of the native polysaccharide, and no new bands were detected. Nonetheless, a comparison of SEM image of ἰ-carrageenan with and without RhCl3, as well as rheological measurements of the aqueous solution of ἰ with and without RhCl3, indicated the incorporation of the polysaccharide with the RhCl3.