تحضير وتشخيص محفزات حامضية صلبة غير متجانسة مشتقة من قشور الأرز لتحضير مشتقات الايميدازول

Synthesis and Characterization of Heterogeneous solid acid catalysts derived From Rice Husks for Imidazole derivatives

Catalysts are very important in our daily life, as they are more efficient and speed up the reaction. Catalysts also have a key property called selectivity, by which they can direct a reaction to increase the amount of desired product and reduce the number of unwanted byproducts. In addition, they can be Reusability as in the catalysts we prepared RH-SiO2PrANSA and RH-SiO2PrOPDA-SO4H, which are solid acid catalysts. The preparation of these catalysts is considered green chemistry, which is the focus of researchers’ attention, as it has the benefit of reducing pollution and getting rid of waste such as rice husks, which are usually disposed of by burning. However, in this research, we prepared catalysts from rice husks and from new components or compounds that researchers have never used before, in environmentally safe and inexpensive ways that do not take much time. Catalysts have been used in many applications such as environmentally friendly industries, medical industries, petroleum refining, etc. They were used in new chemical reactions, namely the preparation of imidazole derivatives. Several techniques have been used to characterize some of the prepared compounds, such as FT-IR Technique, where a appears peak (S=O) group at 1354 cm-1 for RH-SiO2PrANSA and 1465 cm-1 for RH-SiO2PrOPDA-SO4H, also, the (C−Cl) group of RH-SiO2PrCl appears at 698 cm-1, and the XRD diffraction pattern showed a strong and broad peak diffused at 22° (2θ) indicating the amorphous nature of RH-SiO2PrANSA and RH-SiO2PrOPDA-SO4H, according to the FESEM images, the formed structures appear to be irregular and regular in shape, elemental analysis (CHNS) showed the presence of nitrogen and sulfur for RH-SiO2PrANSA and RH-SiO2PrOPDA-SO4H, respectively, which can be regarded as further evidence of the effective incorporation of the organic molecules on the silica surface; as for nitrogen adsorption analysis showed that the specific surface area of RH-SiO2PrANSA and RH-SiO2PrOPDA-SO4H was less than the specific surface area of RH-SiO2PrCl, due to large molecules attached to the surfaces of the functional silica matrix and.
The results of the TGA for the two new catalysts showed two stages for each, the first stage was caused by the loss of water adsorbed on the surface of the sample and the second stage was due to the decomposition of components on the surface of the catalyst.
2,4,5-trisubstituted imidazole derivatives are organic compounds characterized by an imidazole ring containing three substituents at the 2, 4, and 5 positions. In general, 2,4,5-trisubstituted imidazole derivatives have a wide range of potential applications in various fields, making them an important class of compounds for research and development, including pharmaceuticals, polymers and corrosion inhibitors. All synthesized of 2,4,5-trisubstituted imidazole derivatives were characterized using FTIR, 1HNMR and mass spectra. The method has several advantages, for example, these products can be easily monitored, Good production rates can be achieved, shorter reaction times of this reaction method with the reusability of catalyst, by easily filtering the catalyst from the mixture at the end of the reaction.