Chemical grafting of 3-aminipropyl triethoxysilane to carbonized bagasse and acidification of amino groups leads us to introduce a new, efficient and green solid acid catalyst. We used the Fourier-transform infrared spectroscopy (FT-IR), X-Ray Diffraction (XRD), Thermogravimetric analysis (TGA), Field Emission Scanning Electron Microscope (FE-SEM), elemental-mapping and Energy Dispersive X-ray spectroscopy (EDX) for the characterization of the catalyst. This novel catalyst efficiently used to the synthesis of benzo[h]indenoquinolin derivatives and the products were obtained with 80–95% of yields at 3-5 h with high purity. All of the products were characterized by FT-IR, 1H and 13CNMR spectroscopies and compared with authentic samples. Our protocol offers several significant advantages, such as easy preparation of catalyst, green nature of catalyst and reaction media, high yields, good reaction times and easy workup. Manuscript profile

A green and efficient trifluoroacetate-bonded polyethylene graphene oxide composite was utilized in this research to prepare benzimidazoles with good to excellent yield under a solvent-free condition. The trifluoroacetate-bonded polyethylene graphene oxide composite was constructed by polyethylene/diethylenetriamine-functionalized graphene oxide composite bonded by 2-aminothiazole and CF3COOHmoieties. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDS), and thermogravimetric analysis (TGA) were also employed to characterize the composite. Benzimidazoles were synthesized by reacting 1,2-phenylenediamine with aromatic aldehydes in the presence of composite (0.02 g) under solvent-free conditions at 75°C. The composite was recovered and used in five runs without considerable loss of activity. Compared to the other catalysts employed for the synthesis of benzimidazole, the present composite (catalyst) benefits from a series of advantages such as cost-effectiveness, easy storage and handling, recoverability and durability, environmental friendliness, non-metallic nature, and ease of disposal. The present synthetic route has also some advantages, including, moderate condition, easy workup, solvent-free nature, and environmental safety. Manuscript profile