the green synthesis of pyranopyrazole derivatives by silica supported cobalt chloride and cobalt nitrate as a nanocatalyst

In this work, anhydrous cobalt salts of cobalt chloride and cobalt nitrate (cocl2 and co(no3)2) were stabilized on the silica gel surface. characterization of these nanoparticles was investigated by the ft-ir (fourier transform infrared spectroscopy), fe-sem (field emission scanning electron microscope), eds (energy ‐dispersive x‐ray spectroscopy), xrd (x-ray diffraction), and ico-oes (inductively coupled plasma optical emission spectroscopy). furthermore, the efficiency of these nanoparticles was investigated for one-pot synthesis of pyranopyrazole and spiropyranopyrazole derivatives via a four-component reaction of hydrazines, ethyl acetoacetate, aldehyde or isatine derivatives, and malononitrile or ethyl cyanoacetate under green media. the obtained data from edx and ico-oes analyses confirm the amount of cobalt metal in sio2@cocl2 is more than that in sio2@co(no3)2. the availability and reusability of sio2@cocl2 catalyst without its significant reduction in catalytic efficiency during six runs, suitable reaction times, easy workup procedure and good efficiency are some advantages of this green procedure.