Ultrasound irradiation promoted synthesis of bispyrimidine and bispyrazolines as selective adsorbents for the selective removal of Ag(I) and Pb(II) from aqueous solutions

In this paper, a new series of five-membered heterocyclic compounds containing pyrazoline and pyrimidine nucleus were synthesized under both conventional and ultrasonic irradiation conditions. In the first step, bischalcone derivatives were prepared by Claisen-Schmidt condensation of bisaldehydes and acetophenone in alkaline ethanol under conventional and ultrasonic conditions. In the second step, bispyrimidine and bispyrazolines were synthesized by the condensation reaction of bischalcones with thiourea/phenyl hydrazine in an alkaline medium. The ultrasound-assisted synthesis provides excellent yields in short reaction times at room temperature. The structures of the newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, mass and elemental analysis. The new synthesized bispyrimidine and bispyrazoline were used as new adsorbents for the excellent selective removal of silver and lead ions from aqueous mixed metal ion solution containing Cu(II), Co(II), Ni(II), and Zn(II) by batch technique. Also, the quantitative desorption was achieved for lead and silver ions with 0.5 M of HNO3 and HCl solutions, respectively.