## 2 Results
### CuAAC Reactions in Flow  
Initial continuous-flow CuAAC experiments (Table 2) focused on benchmarking the devices based on the **M7**-Cu (OTf)\({}_{2}\) material. Besides two monolithic reactors of different lengths (10 and 15 cm, respectively), this part of the study included the analogous packed-bed continuous flow reactor (PCFR). The latter was assembled by filling a stainless steel column (15 cm length \(\times\) 4.6 mm internal diameter) with powder obtained by grinding chunks of the **M7**-Cu(OTf)\({}_{2}\) monolith involved in the characterization measurements discussed above. The CuAAC runs were carried out by employing a syringe pump, which was used for flushing the reactor with a solution of the selected reducing agent and then with a solution of internal standard and equimolar propargyl alcohol and benzylazide. The examination of different reductants for the Cu(II) metal centers in the MCFR (15 cm) or PCFR afforded results that closely mirror those already recorded in batch. Indeed, hydroquinone in THF \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Entry a** & **CuX1-2** & **Reducing** & **R1, R2** & **Solvent** & _Conv._ \\ \hline  & **(S/C) b** & **agent c  & **(volume ratio)** & **(\%) d \\ \hline
1 & CuCl (10) & - & Ph, CH\({}_{2}\)OH & CH\({}_{2}\)Cl\({}_{2}\) & 71/\(>\)99 \\
2 & CuCl (20) e  & - & Ph, CH\({}_{2}\)OH & CH\({}_{2}\)Cl\({}_{2}\) & 54/\(>\)99 \\
3 & CuCl (50) e  & **(\%) d \\
4 & CuCl (50) e  & - & Ph, CH\({}_{2}\)OH & CH\({}_{2}\)Cl\({}_{2}\) & 31/\(>\)99 \\
5 & CuCl (50) e  & - & Ph, CH\({}_{2}\)OH & CH\({}_{2}\)Cl\({}_{2}\) & 31/\(>\)99 \\
6 & CuCl (50) e  & **(\%) d \\
7 & CuCl (7f)\({}_{2}\) (20) e  & **(\%) d \\
8 & CuCl (7f)\({}_{2}\) (20) HQ & Ph, CH\({}_{2}\)OH & THF & \(<\)5/\(<\)5 \\
9 & Cu(OTf)\({}_{2}\) (20) e  & **(\%) d \\
10 & Cu(OTf)\({}_{2}\) (20) e  & **(\%) d \\
11 & Cu(OTf)\({}_{2}\) (100) e  & **(\%) d \\
12 & Cu(OTf)\({}_{2}\) (100) e  & **(\%) d \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) runs in batch with **P7** loaded with turned out to be completely useless (Table 2, entries 1 and 8), while the addition of phenylhydrazine to the reactant stream proved moderately effective (Table 2, entries 2 and 9). In this latter case, however, the reaction progress at the reactor outlet was largely incomplete, in spite of the rather low flow-rate (\(\mathrm{\upmu}\) = 0.4 mL h\({}^{-1}\)) adopted in the run. On the contrary, good levels of conversion of the azide were attained if sodium l-ascorbate was used in the preliminary reduction step and then employed for saturating the stream of reactants in the subsequent CuAAC runs. Under these conditions, the complete consumption of benzylazide was achieved in a relatively long experiment (\(S\)/\(C\) = 67) carried out at \(\mathrm{\upmu}\) = 1.5 mL h\({}^{-1}\) in the MCFR (10 cm) (Table 2, entry 3). The increase of the flow-rate to 12 mL h\({}^{-1}\), followed by its progressive decrease to the value of the initial run, led to conversion degrees that reflect the average residence time of the reactants through the catalyst bed (Table 2, entries 3-7). Similarly, the use of sodium l-ascorbate for reducing the powdered material in the PCFR considerably improved its catalytic activity with respect to the use of hydroquinone or phenylhydrazine (Table 2, entries 8 and 9). This allowed 57% conversion to be attained at room temperature and with a flow-rate as high as \(\mathrm{\upmu}\) = 6 mL h\({}^{-1}\) (Table 2, entry 10). Further experiments with the PCFR were carried out at 60 \({}^{\circ}\)C and with \(\mathrm{\upmu}\) = 3 mL h\({}^{-1}\). Under these conditions, good to high conversion levels were recorded in a sequence of five runs (Table 2, entries 11-15). The next stage of the investigation focused on PCFRs containing the bead-type complex **P7**-CuSO\({}_{4}\) reduced with sodium l-ascorbate. With this aim, sections of PTFE tubing (18 cm \(\times\) 1.5 mm inner diameter) were packed with the resin beads (80-85 mg, approx.