Synthesis and Characterization of Nano-Cellulose Immobilized Phenanthroline–Copper (I) Complex as a Recyclable and Efficient Catalyst for Preparation of Diaryl Ethers, N-aryl Amides and N-aryl Heterocycles

Nanocellulose supported phenanthroline-copper (I) complex was prepared as a recoverable and cost-effective catalyst for preparation of diaryl ethers, N -aryl amides and N -aryl heterocycles via C-O and C–N cross-coupling reactions. The recoverability experiments exhibited that it can be promisingly reused up to 10 times with negligible change in catalytic activity. Functionalized nanocellulose was prepared and employed for immobilization of phenanthroline-copper(I) complex to afford cellulose nanofibril grafted heterogeneous copper catalyst [CNF-phen-Cu(I)]. This nanocatalyst was well characterized using FT-IR, NMR, XRD, CHNS, AAS, TGA, EDX and SEM. The activities of the synthesized catalyst were examined in the synthesis of diaryl ethers via C-O cross-coupling of phenols and aryl iodides, as well as, the preparation of N -aryl amides and N -aryl heterocycles through C-N cross-coupling of amides and N-H heterocycle compounds with aryl halides. In this trend, various substrates containing electron-donating and electron-withdrawing groups were exploited to evaluate the generality of this catalytic protocol. Accordingly, the catalyst demonstrated remarkable catalytic efficiency for both C-N and C-O cross-coupling reactions, thereby resulting in good to excellent yields of the desired products. Furthermore, the recoverability experiments of the catalyst showed that it can be readily retrieved by simple filtration and successfully reused several times with negligible loss of its catalytic activity.