Preparation and characterization of nanomagnetic piperidinium benzene‐1,3‐disulfonate ionic liquid as a novel, green and heterogeneous catalyst and its use in the synthesis of 1<i>H</i>–pyrazolo[1,2‐<i>b</i>]phthalazine‐5,10‐diones and 1<i>H</i>–pyrazolo[1,2‐<i>a</i>] pyridazine‐5,8‐diones under solvent‐free conditions

Abstract

The one‐pot four‐component synthesis of 1 H –pyrazolo[1,2‐ b ]phthalazine‐5,10‐diones and 1 H –pyrazolo[1,2‐ a ]pyridazine‐5,8‐diones was carried out from the reaction between various aldehydes, malononitrile, hydrazine hydrate and phthalic anhydride or maleic anhydride at 110 °C in solvent‐free conditions using piperidinium benzene‐1,3‐disulfonate nanomagnetic ionic liquid (NMIL) as a novel and reusable catalyst. Some advantages of the presented procedure are a significant reduction in cost, effective catalysis and reusability of the catalyst. NMIL was thoroughly characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning and transmission electron microscopies, thermogravimetry, derivative thermogravimetry, B runauer–Emmett–Teller analysis , vibrating sample magnetometry and energy‐dispersive X‐ray spectroscopy. The technique is developed as a suitable and safe method for the synthesis of 1 H –pyrazolo[1,2‐ b ]phthalazine‐5,10‐diones and 1 H –pyrazolo[1,2‐ a ]pyridazine‐5,8‐diones making use of an efficient and reusable green catalyst.