Studies On The Substance Such As The Schiff Bases Reaction At Supersonic Speed Air-flow Impacting

Mechanochemical synthesis has drawn increasing attention from chemists and materials scientists, which provides an efficient, clean, and high-yielding organic processes in modern synthetic chemistry. In general, mechanochemical synthesis is realized according to mechanical ball milling, hand grinding, twin screw extrusion and microwave. However, these methods suffer from many drawbacks, for example, high cost, long reaction time, small scale and so on. Therefore, development of novel mechanochemical synthesis methods is highly desirable. Supersonic speed air-flow impacting exhibit various advantages, such as batch preparation, simple operation, short time, low energy consumption, safe and environment-friendly compared with traditional mechanical chemical synthetic method. In this thesis we have studied four organic reactions under supersonic speed air-flow impacting conditions.?1? The feasibility of this method was demonstrated via the preparation of three Schiff bases, four theophylline pharmaceutical co-crystals, four metal organic frameworks and polyaniline as the model compounds. The as-prepared products were characterized by Fourier transform infrared ?FT-IR? spectroscopy, powder X-ray diffraction ?XRD?, differential thermal analysis ?DTA?, nuclear magnetic resonance ?¹H NMR?, ultraviolet-visible ?UV-vis? spectroscopy, scanning electron microscopy ?SEM? and single crystal X-ray diffraction ?SCXRD?. All the results indicated that those products were successfully synthesized.?2? To investigate the change regularity of the different reactions along with the different reaction times, the DTA and XRD techniques were used for studying the air-flow impacting preparation process. By implication, DTA and XRD curves indicate that the reaction has occurred after one or two circular reaction. Compared with the conventional mechanochemical synthesis methods, the results demonstrated that air-flow impacting method can achieve rapid response and is environmentally friendly as it avoids the use of various organic solvents. In addition, with the reaction time is determined, it will lend deep-seated technical support to the next step of the research.?3? To investigate the mechanisms and kinetics of the reactions, an ex situ UV-vis absorption spectrometry technique was used for studying the air-flow impacting preparation process. For N,N'-bis?m-nitrobenzylidene?-p-phenylenediamine ?compound 1?, the experimental data was consistent with 2 the D2 kinetic model, indicating that the mechanism of compound 1 belonged to the two-dimensional diffusion-controlled model. The D2 model refers to diffusion and occurs radially through a cylindrical shell and with an increasing reaction zone. For N,N'-bis?2-hydroxy-1-naphthylmethylene?-p-phenylenediamine ?compound 2?, the data were consistent with the A4 kinetic model, which is the two-dimensional diffusion-controlled product growth following deceleratory nucleation. Deceleratory nucleation suggests that the nucleation sites are not saturated at the start of the reaction but are activated one-by-one. Fitting the experimental data to the Avrami-Erofe'ev model enabled us to determine the rate constants of compound 1 and compound 2 as K1=0.018S^-1 and K2=0.01 S^-1.