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le systems, which were synthesized by two parts of process, including sequential direct fluorination of1, 3-diketones and following cyclisation of the generated fluorodiketone with a hydrazine derivative (Fig.6). The reaction was prepared by a sequential telescoped two step of continuous flow process (gas-liquid at first step and liquid-liquid at second step). The continuous flow synthesis technology was used for better temperature control, high yield of production, efficient process18.

Christopher B et al. used continuous liquid-gas flow reactors to apply on a range of selective fluorination reactions, such as direct fluorination of aromatic, dicarbonyl, dieter and benzaldehyde derivatives (Fig.7). The reactions involving the fluorine gas are presented as similar continuous flow synthesis of the oxidation processes19.

4.Liquid-gas-solidthree phase reaction
The hydrogenation is usually a gas-liquid-solid heterogeneous catalytic chemical reaction, which requires molecular hydrogen, chemical compound and a solid catalyst. Increase of the efficiency for mass transfer from the liquid to the solid catalyst surface is critical for the reactions. Most of the hydrogenation reactions are extremely exothermic. Therefore, the hydrogenation has advantages by using the continuous flow system compared to the batch flow system, such as temperature control, higher yield of production and more safety. Sebastian et al. have successfully demonstrated a continuous flow method to complete the gas-liquid-solid hydrogenation reaction of CO2 to pure formic acid (Fig.8). The Ru catalyst is fixed on the surface of the channels, the gas and the liquid is allowed to flow through the channels. The catalyze hydrogenation enable to control the temperature at room temperature and achieve a high yield, which is related to the large contact areas between all the chemical reagents20.

The aim of this assay is to give acomprehensive overview on the principles of continuous flow technology and evaluate its pros and cons of the continuous flow processes. The continuous flow system is mainly consist of two parts: the micro reactors and pumps. The fabrication and characterization of micro reactors will depend on the material used for channel network.The whole reaction process can be achieved by automatic computer programs and monitored on line real-time. The outstanding properties of this technology are its high safety performance and remarkably speed of heat and mass transmission. And there are also some disadvantages in the continuous flow system, such as expensive materials, suffering from restricted fluid flow capacity and high pressure drop. Recently, the continuous flow technology offers animproved way to perform better reactions and widely apply in organicmolecular and drug synthesis. In reactions of all multiple phases, the continuous flow technology will offer great temperature control, high yields of production and less wastes. As a result, it is very clear that the synthetic chemistry will benefit from the development of the continuous flow technology. And it also require more optimization step to transfer the continuous flow system from laboratorial scale to industrial scale in the organic and pharmaceutical industry.

Uncategorized References 参考文献
1.Jas G, Kirschning A. Chem. Eur. J. 2003;9:5708-5723.
2.Fletcher PD, Haswell SJ, Pombo-Villar E. Tet