Unravel the surface active sites on Cu/MgLaO solid base catalyst by DRIFT spectroscopy and adsorption techniques for the synthesis of triazoles by click reaction

Abstract Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy explored the surface basicity of Cu supported on MgO, La2O3 and MgLaO catalysts in the Click reaction of aryl alkyne and aryl azide for the synthesis of substituted triazoles by using formic acid as a probe. Ionic copper in combination with surface basic sites played a prominent role for a high rate of the desired product over 5 wt%Cu/MgLaO catalyst at 70 °C and water as solvent in the absence of a base. A structure-activity correlation established for the Click reaction using in situ DRIFT spectroscopy and based on the Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), H2- temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), N2O titration and temperature programmed desorption (TPD) of CO2 analyses plausible reaction mechanism was established. The bulk and surface properties of the recovered 5 wt%Cu/MgLaO revealed that the catalyst was stable even after 4 recycles.