## 2 Materials and Methods  
### Materials  
For the experiment, chemicals of analytical purity were used without additional purification. Polyvinylpyrrolidone (PVP (M\({}_{\rm w}\) = 10,000)) was purchased from AppliChem (Ottoweg 4, 64291 Darmstadt, Germany). The following were used: iron chloride (FeCl\({}_{3}\cdot\)6H\({}_{2}\)O) and iron sulfate (FeSO\({}_{4}\cdot\)7H\({}_{2}\)O) of chemically pure grade, manufactured in Russia; Co(NO\({}_{3}\))\({}_{2}\cdot\)6H\({}_{2}\)O of chemically pure grade, manufactured in Russia; and ammonium hydroxide (25%) of chemically pure grade, manufactured in Russia. Iron (III) chloride hexahydrate (FeCl\({}_{3}\) 6H\({}_{2}\)O, of \"reagent grade\"), cobalt (II) nitrate hexahydrate (Co(NO\({}_{3}\))\({}_{2}\cdot\)6H\({}_{2}\)O, of \"reagent grade\"), and ammonium hydroxide (25% NH\({}_{4}\)OH, of \"reagent grade\") were used to obtain spinel ferrites by coprecipitation. In order to ensure intensive mixing during the synthesis of magnetic composites, a 250 mL glass mini-reactor equipped with a stirrer with a speed controller up to 1500 rpm was used. Synthesis of CoFe\({}_{2}\)O\({}_{4}\) and CoFe\({}_{2}\)O\({}_{4}\)/Polyvinylpyrrolidone Magnetic Composite Catalyst  
Nanosized magnetic composites stabilized with PVP (M\({}_{\rm w}\) = 10,000) based on cobalt ferrite were obtained by chemical precipitation. Nanocrystals of the magnetic composite stabilized with PVP were obtained by the chemical coprecipitation of the corresponding salts: divalent cobalt and trivalent iron ions in an alkaline solution. For the synthesis of CoFe\({}_{2}\)O\({}_{4}\)/PVP, an aqueous solution of iron (III) Fe(NO\({}_{3}\))\({}_{3}\times\)6H\({}_{2}\)O nitrate and cobalt (II) Co(NO\({}_{3}\))\({}_{2}\times\)6H\({}_{2}\)O nitrate and PVP were mixed for three minutes in a vortex mode in an electromagnetic homogenizer; then, in a mini reactor in an inert medium (argon) with intensive stirring (600 rpm), a 25% ammonia solution (pH-10) was added drop by drop to the resulting suspension at a temperature of 40 \({}^{\circ}\)C. The resulting black precipitate of the composite was washed by decanting with bidistilled water and separated using a neodymium magnet and dried at a temperature of 90-100\({}^{\circ}\). A detailed description of the methodology for obtaining catalysts and conducting experiments is described in our previous articles [37; 47; 58]. The composition and structure of the synthesized catalysts were determined by SEM, X-ray diffraction, TGA, and IR Fourier spectroscopy. The reaction products were analyzed by high-performance liquid chromatography (HPLC). Determination of Structural Characteristics of the Obtained Magnetic Composites and Process Products  
Diffraction patterns were measured in the Bragg-Brentano geometry in the angle range of 20 = 15-100\({}^{\circ}\). All results were processed under atmospheric pressure of 101,325 Pa = 760 mm Hg and T\({}_{\text{air}}\) = 20 \({}^{\circ}\)C. The Profex 5.0.2 program was used for the qualitative and quantitative analyses of the diffraction patterns. Quantitative analysis was performed in the program using the Rietveld method with the criterion of the minimum value of the root-mean-square deviation \(\chi^{2}\). Qualitative analysis was performed based on the results of the energy-dispersive analysis of SEM. The average diameter of the synthesized composites was calculated from the width of the X-ray line using the Debye-Scherrer equation. The IR spectra of magnetic composites were recorded on a Vertex 70v IR Fourier spectrometer (Bruker, 76275 Ettlingen, Germany) with a resolution of 4 cm\({}^{-1}\), with a computer system for recording and processing spectra in the wavenumber scanning range of 4000-500 cm\({}^{-1}\) using a PIKE MIRacle ATR single attenuated total reflection (ATR) attachment with a germanium crystal. The results were processed using the OPUS 7.2.139.1294 software. The thermogravimetry method was used to assess the crystallization and sorbed water content of the samples.