Novel heterogeneous catalyst for green synthesis of imidazole derivatives: environmental sustainability metrics assessment

We present a novel catalyst, cerium phosphate (CeP₂O₇), synthesized via a straightforward co-precipitation method and comprehensively characterized using X-ray diffraction, FTIR, scanning electron microscopy (SEM), EDS mapping, and EDS techniques. Furthermore, the acidic sites of the catalyst were determined using pyridine FTIR spectroscopy. Characterization results revealed the ball-like morphology of the catalyst with mean diameters of 51 nm as well as uniform distributions of the desired elements (Ce, O, and P). CeP₂O₇ demonstrates remarkable catalytic performance in the imidazole reaction involving ammonium acetate, benzil, and various aldehydes. Several parameters including reaction temperature, amount of catalyst, and type of solvent were studied. It was demonstrated that the best solvent for the synthesis of imidazole was ethanol at 70 °C. Exceptional product yields (90–96%) are achieved within just 12 min. The catalyst’s heterogeneity is confirmed through a hot filtration test. CeP₂O₇ offers notable advantages, including easy recovery and reuse for a minimum of five cycles, straightforward work-up procedures, and high product yields. Sustainability evaluation based on green metrics, such as E-factor, atom economy (AE), reaction mass efficiency (RME), carbon efficiency (CE), and optimum efficiency (OE), underscores the catalyst’s role in enhancing environmental sustainability.