Synthesis of 2-arylbenzothiazoles using a novel MWCNTs@Zeolite@Fe3O4 NPs catalyst in DES

This study reports the development and application of a highly efficient and recyclable heterogeneous catalyst for the sustainable synthesis of 2-arylbenzothiazoles. The catalyst consists of a novel magnetic composite in which multi-walled carbon nanotubes are supported by zeolite and Fe 3 O 4 nanoparticles (MWCNTs@Zeolite@Fe 3 O 4 NPs). It was prepared via a straightforward approach and characterized in detail by a range of analytical techniques, including FT-IR, XRD, FE-SEM, EDX, TEM, VSM, and BET surface area analysis. The catalytic performance was evaluated in the condensation reaction between 2-aminothiolphenol and various aromatic aldehydes under environmentally benign conditions at room temperature. Optimization studies identified ChCl/urea (1:1) deep eutectic solvent as the optimal medium, delivering excellent yields of the target benzothiazoles (89–97%) within short reaction times (60 minutes). The catalyst demonstrated exceptional recyclability, maintaining activity for six consecutive cycles with only minimal loss of efficiency, and it could be readily recovered by external magnetic agitation. Post-recycling analyses confirmed the catalyst's structural integrity and stability. The methodology offers multiple advantages, including mild reaction conditions, facile magnetic separation, high atom economy, and the use of a biodegradable DES system. This environmentally conscious approach underscores the potential for sustainable practices in pharmaceutical synthesis, contributing to greener chemical processes.