A new simple method for the preparation of PbO nanoparticles and implementation of an efficient and reusable catalytic system for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones

PbO was explored as a highly efficient, simple, cheap, and recyclable catalyst for the fast synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives via a one-pot three-component reaction of phthalhydrazide, aromatic aldehyde, and malononitrile under solvent-free conditions at 80 °C. Furthermore, nanosized PbO particles were prepared by the two conventional methods of planetary ball milling and dispersion of commercial PbO in n-octane, and their catalytic performances were compared with the commercial bulk PbO. The prepared nano-PbO via ball milling was characterized by SEM, XRD, EDX, and FT-IR spectroscopy. The present protocol conveyed major advantages such as the use of an inexpensive and readily available catalyst, easy workup and purification of products by non-chromatographic method, low reaction times, and improved yields under relatively environmentally benign conditions. The non-toxic catalyst was conveniently recyclable and could be reused several times without loss of activity.