A Rare Carbon Skeletal Oxidative Rearrangement of Camphene Catalyzed by Al‐Exchanged Keggin Heteropolyacid Salts.

In this work, aluminum‐exchanged Keggin heteropolyacid salts (i. e., AlPW12O40, AlPMo12O40, and Al4/3SiW12O40) were synthesized and evaluated as catalysts on the camphene oxidation with hydrogen peroxide. The aluminum silicotungstate salt (i. e., Al4/3SiW12O40) was the most active and selective toward formation of borneol and two novel products; 1‐(3‐(2‐hydroxypropan‐2‐yl) cyclopentyl) ethan‐1‐one, and 3‐(3‐hydroxycyclopentyl)‐3‐methylbutan‐2‐one), which were spectroscopically characterized (FT‐IR, 13C and 1H NMR analyses). All the catalysts were characterized by FT‐IR/ ATR spectroscopy, BET, XRD, EDS/SEM, and TG/DSC analyses. After the characterization of the HPA salts, it was possible to link their structural properties to their catalytic activity. The effects of the main reaction variables were assessed. The aluminum cation as well as the silicotungstic anion showed to be essential to formation of three goal‐products. [ABSTRACT FROM AUTHOR]