Synthesis of 2,3-dihydro-4(1 H) quinazolinones using a magnetic pectin-supported deep eutectic solvent

Abstract

Deep eutectic solvents (DESs) are an emerging type of ionic liquids with amazing properties such as benign nature and tunability. Despite these advantages, recovery issues restrict their use, and immobilization serves as a viable solution. However, choosing a support material is a challenging step in view of sustainability and eco-friendliness. Therefore, in this work we introduced for the first time a recoverable deep eutectic solvent immobilized on pectin (Pec) as a naturally-occurring support using metformin (Met) as a hydrogen bond donor, and choline chloride (ChCl) as hydrogen bond acceptor. Then, these nanoparticles (Pec-Met-ChCl) were magnetized by immobilizing magnetic Fe3O4 nanoparticles to produce MNPs-Pec-Met-ChCl catalyst. The stable and heterogeneous nature, existence of hydrogen bond donating groups and subsequently an effective interaction with substrates specify the catalyst activity of MNPs-Pec-Met-ChCl nanocomposites. The presence of Fe3O4 magnetic nanoparticles not only provides a clean and simple recovery, but also improves the catalytic activity. The heterogeneity of MNPs-Pec-Met-ChCl was also inspected by hot filtration test under the optimum reaction conditions. This novel catalytic system with properties including eco-friendly, adjustability, sustainability, easy recoverability, and reusability provides high performance in the synthesis of various aromatic and heteroaromatic 2,3-dihydro-4(1H)-quinazolinone derivatives under solvent-free conditions. Also, green metrics calculations showed that this procedure is quite efficient as compared to other homogeneous and heterogeneous catalytic systems, while it produces less waste, which is more favourable in view of green chemistry. Furthermore, FT-IR, EDX, and XRD of the reused catalyst after 6th run displayed its remarkable endurance.