Oxidative carbonylation of glycerol to glycerol carbonate catalyzed by PdCl2(phen)/KI

We present a direct and highly efficient approach for synthesizing glycerol carbonate, via the catalytic oxidative carbonylation of glycerol, using PdCl2(phen) (phen = 1,10-phenanthroline) as catalyst with the aid of KI. The palladium catalyst loading as low as 0.25 mol% is sufficient for high conversion (92%) and selectivity (99%) at the reaction condition: 2.0 MPa CO, 1.0 MPa O2, 140 °C, 2 h. The turnover frequency (TOF) reaches 184 h−1. Furthermore, using crude glycerol, we achieved 85% conversion of glycerol. We discuss in detail a plausible mechanism based on PdI2(phen) as an intermediate. We propose that there is synergistic effect of I− and 1,10-phenanthroline on the performance of the Pd complex catalyst. Based on the cyclic voltammograms, the reduction of PdI2(phen) occurred at a more positive potential than that of PdCl2(phen). This may explain why the catalytic activity of PdI2(phen) was more effective than that of PdCl2(phen).

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (75 K)Download as PowerPoint slideResearch highlights▶ Oxidative carbonylation is an efficient method for synthesizing glycerol carbonate. ▶ PdCl2(phen)/KI was successfully employed in the reaction for the first time. ▶ I− and phen complexes used in the reaction show synergistic effect on the activity. ▶ Oxidative carbonylation of glycerol present a new platform to valorize glycerol.