Sulfonic acid‐functionalized Fe 3 O 4 ‐supported magnetized graphene oxide quantum dots: A novel organic‐inorganic nanocomposite as an efficient and recyclable nanocatalyst for the synthesis of dihydropyrano[2,3‐ c ]pyrazole and 4 H ‐chromene derivatives

In this research, the main emphasis has been focused on the preparation of a novel Fe 3 O 4 ‐supported propane‐1‐sulfonic acid‐grafted graphene oxide quantum dots (Fe 3 O 4 @GOQD‐ O ‐(propane‐1‐sulfonic acid)) that it was readily synthesized via a five‐step procedure as a hitherto unreported magnetic nanocatalyst. This newly prepared Fe 3 O 4 @GOQD‐ O ‐(propane‐1‐sulfonic acid) nanocomposite was structurally well‐established by different analytical techniques including Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), energy‐dispersive X‐ray (EDX), thermal gravimetric analysis (TGA), field emission gun‐scanning electron microscope (FESEM), high‐resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM) analyses. The high catalytic performance of this nanocomposite was exhibited in one‐pot synthesis of dihydropyrano[2,3‐ c ]pyrazole and 4 H ‐chromene derivatives under mild conditions. Low reaction times, excellent yields of the products, benignity of the catalyst, easy reaction work‐up and magnetic recyclability of the catalyst are the main advantages of the present protocol. Also, our research indicated that the Fe 3 O 4 @GOQD‐ O ‐(propane‐1‐sulfonic acid) could be reused up to five times without considerable loss of catalytic activity.