*3.5. Catalytic Studies*

The microwave-assisted peroxidative oxidation of cyclohexane was carried out in G10 Pyrex tubes (10 mL capacity reaction tube with a 13 mm internal diameter) in a focused Anton Paar Monowave 300 reactor (Anton Paar GmbH, Graz, Austria) fitted with a rotational system and an IR temperature detector.

The test was performed under the following conditions: The desired amount of catalyst **1**, **2**, or **3** (2.5–20 μmol); cyclohexane (5 mmol); acetonitrile (3 mL) and oxidant (1, 2, or 4 equivalent vs. substrate, *t*-BuOOH, 70% aqueous solution) were added into an Pyrex tube, which was introduced in the MW reactor and stirred under irradiation (5—10 W) at 50 ◦C. After completion of the desired reaction time, the reaction mixture was cooled to room temperature, whereafter 90 μL of cycloheptanone (internal standard) and 10 mL of diethyl ether (for substrate and organic product extraction) were added. The reaction mixture was stirred and centrifuged. A sample was taken from the mixture and analyzed by gas chromatography (GC) after the addition of an excess of triphenylphosphine, in order to reduce cyclohexyl hydroperoxide to cyclohexanol, following a method developed by Shul'pin [54]. The composition of products was confirmed by Gas Chromatography-Mass Spectrometry (GC-MS).

For the ultrasound-assisted oxidation reactions, a reaction tube was immersed in an ATU ultrasonic thermoregulated bath (40 kHz, 600 W) equipped with an automatic temperature heating-cooling circulatory system, which kept the bath temperature at ca. 50 ◦C for all of the trials.

GC measurements were carried out using a FISONS Instruments GC 8000 series gas chromatograph (Agilent Technologies, Santa Clara, CA, USA) with an FID detector and a capillary column (DB-WAX, column length: 30 m; internal diameter: 0.32 mm), using helium as a carrier gas and the Jasco-Borwin v.1.50 software (Jasco, Tokyo, Japan). The samples were injected at 240 ◦C, whereas the initial temperature was maintained at 100 ◦C for 1 min, increased to 180 ◦C at the rate 10 ◦C/min, and then hold for 1 min.

The samples were analysed by GC-MS using a Perkin Elmer Clarus 600 C instrument (Shelton, CT, USA) (He as the carrier gas). The ionization voltage was 70 eV. Gas chromatography was guided in the temperature-programming mode, using an SGE BPX5 column (30 m × 0.25 mm × 0.25 μm).

Retention times of all identified reaction products were compared with those of the commercially available samples. Reaction products' mass spectra were compared to fragmentation patterns obtained from the NIST spectral library stored in the computer software of the mass spectrometer.
