## 4 Microwave-Assisted Catalytic Peroxidative Oxidation of Cyclohexanol to Cyclohexanone
We have also observed a similar phenomenon for the other compounds (1, 2, and 4) (Figure 8A). Figure 7: (**A**) Plots of yield vs. time for the microwave (MW)-assisted oxidation of cyclohexanol by _tert_-butylhydroperoxide catalyzed by frameworks 1–4. (**B**) Maximum yield of cyclohexanone obtained from the same reaction. Evidence for a free-radical mechanism, as previously proposed [28], arises from addition of the CBrCl\({}_{3}\) or Ph\({}_{2}\)NH radical trap to the reaction mixture, that results in the almost suppression of the catalytic activity compared to the reaction carried out under the same conditions (5 mmol, 70 \({}^{\circ}\)C, MW, 1 h) but in the absence of a radical trap. This suggests the generation of oxygen and carbon radicals in the reaction, which are trapped by such radical scavengers. Thus, the mechanism of cyclohexanol oxidation (see Equations (1)-(6)) may involve the \({}^{t}\)BuO' and \({}^{t}\)BuOO radicals produced in the iron promoted decomposition of TBHP [23] according to Equations (1)-(6), where Cy denotes cyclohexyl and Cy\({}^{\cdot}\)\({}_{\text{H}}\)-OH denotes the radical formed upon H-abstraction from cyclohexanol CyOH [43; 44; 45; 46]. \[\text{Fe}^{3+}+{}^{t}\text{BuOOH}\rightarrow\text{Fe}^{2+}+{}^{t}\text{BuOO}+ \text{H}^{+} \tag{1}\]  
\[\text{Fe}^{2+}+{}^{t}\text{BuOOH}\rightarrow\text{Fe}^{3+}\text{-OH}+{}^{t} \text{BuO} \tag{2}\]  
\[\text{Fe}^{3+}\text{-OH}+{}^{t}\text{BuOOH}\rightarrow\text{Fe}^{3+}\text{-OO} \text{-}{}^{t}\text{Bu}+\text{H}_{2}\text{O} \tag{3}\]  
\[{}^{t}\text{BuO}+\text{CyOH}\rightarrow{}^{t}\text{BuOH}+\text{Cy}^{\cdot} \text{-H}\text{-OH} \tag{4}\]  
\[{}^{t}\text{BuOO}+\text{CyOH}\rightarrow{}^{t}\text{BuOOH}+\text{Cy}^{\cdot} \text{-H}\text{-OH} \tag{5}\]  
\[\text{Fe}^{3+}\text{-OO}\text{-}{}^{t}\text{Bu}+\text{Cy}^{\cdot}\text{-H} \text{-OH}\rightarrow\text{Cy}^{\cdot}\text{-H}=\text{O}+{}^{t}\text{BuOOH}+ \text{Fe}^{2+} \tag{6}\]  
Figure 8: (**A**) Influence of the temperature on the yield of cyclohexanone obtained by MW-assisted oxidation of cyclohexanol with _tert_-butyl hydroperoxide (TBHP) after 1 h reaction time (purple pillars = reactions performed at 60 \({}^{\circ}\)C; red pillars = reactions performed at 70 \({}^{\circ}\)C, and green pillars = reactions performed at 80 \({}^{\circ}\)C). (**B**) Maximum yield of cyclohexanone obtained in consecutive recycles of the MW-assisted oxidation of cyclohexanol by _tert_-butyl hydroperoxide catalyzed by **3** after 1 h reaction time. The catalysts of the present study, being heterogeneous, present the additional advantage of being recyclable. Recycling of catalyst 3 was tested up to six consecutive cycles, and it was found that it maintains almost at the original level of activity for five cycles. After the sixth cycle, 3 retains 87% of its initial activity (Figure 8B). The FT-IR spectra of catalyst 3 were taken before and after the catalysis and no significant change was observed, what suggests that the structure of the solid was retained (Figure S2, Supplementary Materials). Moreover, the amount of iron determined in the filtrate solution, obtained after the separation of the catalyst 3, was only 0.010% of the amount used in the reaction, thus ruling out any significant leaching of the catalyst.