Preparation of modified magnetic silica NPs (Fe3O4@SiO2~Cl)
Initially, the magnetic NPs prepared through a coprecipitation method and coated with a silica layer via a modified sol-gel method [20]. In brief, FeCl3.6H2O (0.036 mol) and FeCl2.4H2O (0.018 mol) were dissolved in deionized water (20 mL) and stirred for 30 min under nitrogen gas atmosphere at 60 °C. Then, NH3 (10 mL, 25%) was added into the solution and the solution color is immediately changed to black. Stirring was continued for more 1 h at 60 °C. The magnetite NPs was collected from the solution using an external magnet, washed several times with deionized water and ethanol, and …show more content…
The reaction mixture was refluxed at 140 °C for 24 h. The functionalized NPs were magnetically filtered and washed with DMF, and finally with deionized water. The solid sample was then dried at 100 °C for 24 …show more content…
Then, isocyanide (1 mmol) was added to the reaction mixture and continued stirring for 4 h at 60 °C. After completion of the reaction, as indicated by TLC, the catalyst was magnetically separated and filtrated solution was diluted with 2 mL deionized water to afford products. The new derivative compounds were characterized by 1H and 13C NMR. The following is the spectral data of