Ion-Pair Anchored Protic Ionic Liquids on Magnetic Nano Silica Sulfuric Acid as Efficient Catalysts for Organic Synthesis

The synthesis of pyrazolo[b]phthalazine diones and indazolo[b]phthalazine triones was efficiently achieved using novel magnetically recoverable supported Bronsted acidic ionic liquids. The heterogeneous catalysts were prepared by synthesizing two organosulfonate salts from n-methylimidazole and 1-benzyl-4-phenyl-1H-1,2,3-triazole with 1,4-butanesultone. The organosulfonate zwitterions were non-covalently immobilized onto the previously synthesized nanomagnetic Fe3O4@SiO2-SO3H support to prepare the organometallic hybrid catalysts. Various thermal and spectroscopic techniques, including H-1 and C-13 NMR, FTIR, SEM, EDX, mapping, XRD, and VSM, were employed to confirm the successful preparation of the novel nanoorganometallic hybrid catalysts. The immobilization of BAILs on the nanoparticles of Fe3O4@SiO2-SO3H facilitated their recycling and improved their thermal stability. This immobilization strategy preserved the flexibility of BAILs, while also allowing for the benefits of both heterogenized and free forms of BAILs. Furthermore, the introduced catalysts demonstrated short reaction times and high yields of products, along with high TON and TOF values, making them superior replacements for previously reported catalysts.

Automated summary

The synthesis of pyrazolo[b]phthalazine diones and indazolo[b]phthalazine triones was efficiently achieved using novel magnetically recoverable supported Bronsted acidic ionic liquids. Heterogeneous catalysts were prepared by immobilizing organosulfonate zwitterions on nanomagnetic Fe3O4@SiO2-SO3H support, leading to improved thermal stability and recyclability. The introduced catalysts demonstrated short reaction times and high yields of products, making them superior replacements for previously reported catalysts.