Magnesium Pyrophosphate-Catalyzed Epoxidation of 1-Octene with Aqueous Hydrogen Peroxide

The epoxidation of terminal olefins (e.g., 1-octene) presents an enormous challenge owing to their electron-deficient nature, whereas the vicinal diols that are derived from epoxides are highly desirable as fine chemicals. We report the facile preparation of magnesium pyrophosphate via the thermal decomposition of commercially available newberyite and the first use of magnesium pyrophosphate as a solid catalyst for terminal olefin epoxidation. The as-synthesized magnesium pyrophosphate was characterized by XRD, FTIR, SEM–EDS, and CO 2 -TPD techniques. The CO 2 -TPD results proved that the medium base was dominant in magnesium pyrophosphate. Magnesium pyrophosphate exhibited an effective catalytic activity in the liquid-phase epoxidation of 1-octene with a 94.2% selectivity of epoxide using aqueous hydrogen peroxide as oxidant in the presence of acetonitrile solvent. The influences of various reaction parameters, including solvent, temperature, H 2 O 2 to 1-octene molar ratio, amount of magnesium pyrophosphate, reaction time, and solvent amount were investigated. According to the reaction mechanism, the perhydroxyl ion that originated from H 2 O 2 heterocracking formed in the presence of magnesium pyrophosphate and reacted with acetonitrile to generate active intermediate peroxycarboximidic acid. The epoxide and amide formed when active oxygen was transferred from peroxycarboximidic acid to the olefin. Therefore, magnesium pyrophosphate was an appropriate catalyst for 1-octene epoxidation. Graphic Abstract