2.2. General Procedure for Catalytic Oxidation under Pressure in 100 mL Volume

The 100 mL oxidation process was carried out in an Autoclave Engineers Inc. pressure reactor, (Erie, PA, USA), made of Hastelloy C-276 steel and equipped with a high-speed stirrer, heating jacket, internal cooler, and reflux condenser. In a typical process, 2 mL of substrate, 20 mL of solvent, and the catalytic system were introduced into the reactor. The reactor contents were purged with O₂ at 2 L/h for 2 min, then heated to 40–100 °C and stirred at 1000 rpm. Subsequently, O₂ was introduced into the reactor under pressure 0.1–1.5 MPa, and the oxidation process was started. The pressure, the stirring speed and temperature were monitored using a Sentinel control device. During the process, the pressure decreased due to O₂ consumption and was supplemented with additional O₂.