C–H bond cyanation of arenes using N,N-dimethylformamide and NH4HCO3 as a CN source over a hydroxyapatite supported copper catalyst
A hydroxyapatite supported Cu catalyst [HAP:Ca5(PO4)3(OH)] has been found to be an efficient and reusable heterogeneous catalyst for safe cyanation of C–H bonds of hetero aryl compounds. The combination of NH4HCO3 and DMF is identified as a CN source under mild reaction conditions. 10 wt% Cu/HAP offered good to excellent yields compared to Ru/HAP and Pd/HAP catalysts. The surface basicity and Cu metal surface area of the catalysts played a significant role in the cyanation reaction through C–H bond activation. The catalyst was recovered and reused for five cycles showing consistent activity and selectivity. The physicochemical characteristics of the catalysts are rationalized by H2-TPR, BET-SA, XPS, TEM and N2O titration techniques.