An environmentally friendly, photocontrollable and highly recyclable catalyst for use in a one-pot three-component Mannich reaction

An environmentally friendly, photocontrollable and highly recyclable catalyst (ZrOPPAZOSO₃H) has been synthesized by the immobilization of 4-[4-(6-phosphonic acid-hexanoxyl)phenylazo]benzenesulfonic acid onto zirconium phosphonate. This catalyst was characterized by Fourier transform infrared, scanning electron microscopy, X-ray powder diffraction, nitrogen adsorption-desorption and UV–vis analyses. The catalytic activity of ZrOPPAZOSO₃H was investigated towards the one-pot three-component Mannich-type reaction of benzaldehyde, aniline and cyclohexanone in water at room temperature, and gave excellent yields. Interestingly, the catalytic activity could be regulated by photoirradiation. Furthermore, upon completion of the reaction, the product could be readily separated by extraction, and the water phase reused in the next run. Lastly, the catalyst could be readily recovered by centrifugation and reused up to six times without any discernible impact on its activity. Copyright © 2016 Elsevier B.V.