## 3 Results and Discussion
### \(\beta\)-Caryophyllene Oxidation
#### 3.5.4 Solvent Influence  
In contrast to the oxidation of \(\beta\)-myrcene, the addition of ethyl acetate led to high conversion (99%) and enhanced oxide formation (57%) with **(BmIm)\({}_{4}\)PMo\({}_{11}\)VO\({}_{40}\)** (Entry C6). The rigid structure of \(\beta\)-caryophyllene may lead to more selective oxidation, as the steric constraints limit unwanted side reactions. The effect was even more pronounced with BuPyr catalysts, with oxide formation (42%, Entry C10) higher than in the organic-solvent-free condition (15%, Entry C9). This highlights once again the substrate-dependence selectivity and the effect of the solvent. The same trend was also observed in the case of TBHP\({}_{\text{dec}}\). The oxide yields increased in both tested cases (Entries C8 and C12), showing slightly higher yields than in the case of TBHP\({}_{\text{aq}}\) (Entries C7 and C11), which may be caused by the higher solubility in the decane and _tert_-butanol produced as a by-product. In addition, a maximum of 11% of conversion was obtained with naked **MR**, confirming the crucial role of the POMs in the transformation, which was also seen in the case of \(\beta\)-myrcene. 3.5.5. Effect of H\({}_{2}\)O\({}_{2}\) as Oxidant with Immobilized POMs  
Only **MRImd@PMo11V1O40**, whose homogeneous analog has demonstrated higher reactivity, was evaluated. With H\({}_{2}\)O\({}_{2}\), the tested grafted catalyst that had the highest efficient selective oxidation showed behavior almost similar to its non-grafted counterparts, with slightly lower conversion in the grafted form (Entries C5 and C16). 3.5.6. Effect of TBHP as Oxidant with Immobilized POMs  
With TBHP\({}_{\text{aq}}\), oxide formation was the same in both cases (grafted and non-grafted) and the same formations were obtained in the two cases (62%) (Entries C7 and C17), with slightly lower conversion in the grafted form. In addition, the use of TBHP\({}_{\text{dec}}\) with \(\beta\)-caryophyllene also yielded the best overall oxidation performance, with 98% conversion and 66% oxide formation (Entry C8), with the same tested catalyst in both grafted and non-grafted forms. 3.5.7. Leaching Experiment with **MRImd@PMo11 VO40**  
Before evaluating the recyclability of the supported catalysts, leaching experiments have been conducted (Table 3, Entries C19 and C20 and Figure 6) in order to assess the nature of the catalytic process (homogeneous or heterogeneous). Based on the oxidation of \(\beta\)-caryophyllene, two reactions were conducted using **MRImd@PMo11 VO40** as a catalyst and TBHP\({}_{\text{aq}}\) as an oxidant. The first one has been conducted under classical conditions: 5 h at 80 \({}^{\circ}\)C (\"unfiltered reaction\" in gray). For the second reaction, after 1 h, the catalyst was removed by filtration (\"filtered reaction\" in blue) and the resulting reaction mixture was maintained at 80 \({}^{\circ}\)C under stirring for 4 h. For the unfiltered reaction, both the conversion of \(\beta\)-caryophyllene and oxide yields increased between 1 h and 5 h (from 62% to 92% for the conversion and from 20% to 62% for the oxide yields, Entries C17 and C19). Concerning the filtered reaction, a slight increase in the conversion was observed between 1 h and 5 h (from 62% to 71%, Entries C19 and C20) but no oxide was formed after the filtration of the catalyst (Entries C19 and C20). Based on the slight increase in \(\beta\)-caryophyllene conversion, leaching of the POM might be initially envisioned. However, no phosphorous-based species was detected by liquid \({}^{31}\)P[\({}^{1}\)H] NMR of the filtrate and the formation of the oxide stopped after filtration. In addition, the oxide could not be obtained without the presence of the catalyst, as proved by  
Figure 6: Leaching experiment test for the oxidation of \(\beta\)-caryophyllene with **MRImd@PMo11 VO40** as a catalyst and TBHP\({}_{\text{aq}}\) as an oxidant. Bars correspond to the conversion of \(\beta\)-caryophyllene (gray: unfiltered reaction, blue: filtered reaction after 1 h) reactions.