This work reported LiCl-promoted branched selective methoxycarbonylation of propylene utilizing a heterogenized Pd/3V-PPh₃@POP catalyst. The presence of LiCl gave a 36.9% increased branched selectivity with a useful turnover number of 124.5 compared to the absence of additives.

Abstract

Branched selective carbonylation of propylene is a well-known challenge for both academia and industry. In this study, we reported LiCl-promoted branched selective methoxycarbonylation of propylene utilizing an easy heterogenized triphenylphosphine-palladium catalyst (Pd/3V-PPh₃@POP). Various (heterogenized) ligands, additives, acids, and catalytic metals were tested. The catalyst Pd/3V-PPh₃@POP in the presence of LiCl gave a 36.9% increased branched selectivity at the expense of activity compared to the absence of additives (71.4% versus 34.5% branched selectivity, turnover numbers of 124.5 versus 421.8) under otherwise identical conditions. The optimal catalyst Pd/3V-PPh₃@POP was characterized using X-ray diffraction (XRD), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), scanning electron microscopy energy dispersive spectrometer (SEM-EDS), Brunner–Emmet–Teller (BET), and thermogravimetric analysis (TGA) experiments and further tested in simple filtration recycling experiments using a continuous stirring reactor.