| Microfluidics is the science and technology of systems that process or manipulate small (10-9 to 10-18 litres) amounts of fluids, using channels with dimensions of tens to hundreds of micrometres. Compared to macroscale laboratory techniques, microfluidic reactors have a number of advantages over conventional chemical processes, which would be expected to promote highly effective chemical reactions in the microchip.In the chapter 1, the main feature of microfluidic reactors,the method to drive liquid through the microchannels, the method for mixing liquids in microchennels and the organic synthesis reactions carried out in microfluidics reactors were reviewed.In the chapter 2, the Claisen-Schmidt reaction was carried out in glass microfluidic chips with two Y-shaped inlets. The effect of interfacial area on the rate of phase transfer reaction was studied and discussed. 93% and 80 conversions were obtained after 8 min reaction in microchannels in width of 300 and 500μm, respectively. In comparison, 60% conversion was obtained in a bulk reaction with vigorous stirring. Even the reaction time was doubled to 16 min, only 73% conversion could be achieved. It has been observed that by introducing the reactants into microchannels at the same linear flow rate of 12.0 cm/min, slug flow was formed reproducibly in the 300-μm wide microchannel and laminar flow was formed in the 500-μm wide microchannel. Slug flow provides faster mass transfer than laminar flow. The demonstrated advantages of organic synthesis in microfluidic chip included faster reaction rate, less consumption of reactants and labor contaminant, which proved microfluidic chip to be a powerful tool for synthetic applications.In the chapter 3, a novel experiment system and method for organic synthesis in a microfluidic chip was developed, in which a negative pressure delivery device was used to drive reactants through the microchannels at a constant low flow rate. The negative pressure delivery device consists of a micro-vacuum air pump, a buffer vessel, a regulating value, a vacuum gauge and a newly developed interface to ensure airtight. The phase-transfer reaction for synthesis of 4-methoxy- benzaldehyde oxime from 4-methoxybenzaldehyde and hydroxylammonium chloride was carried out in glass microfluidic chips by using the developed negative pressure system. The effect of reaction time on yield was determined and compared with the standard batch system. The developed experiment system and method for organic synthesis in a microfluidic chip has been proved to be easy to operation, flow-stable and inexpensive, compared to the conventional sampling methods, such as using micro-pump and electroosmotic flow.In the chapter 4, the effect of flow rate, dimension of the microchannels and inlet shape of the microfluidic chip on the flow pattern inside the microchannel was systematically studied. It has been found that not only Capillary number, which was usually used to characterize the flow pattern inside the microchannel, but also dimension of the microchannels and inlet shape of the microfluidic chip also affect the flow pattern. Experiments showed that slug flow offers a simple method of achieving rapid mixing. It was easy to form slug flow in the smaller channels and low flow velocity. By optimization of the inlet shape of the microchannels, the threshold velocity for forming slug flow in the larger (500μm in width) channels has greatly improved. Rapid mass transfer between organic and aqueous phases in optimized microfluidic reactors with double T and crossing inlets was realized, which is 13-15 fold faster than conventional reactors with Y inlet. 70% conversion for synthesis of cyclohexane oxime from cyclohexanone and hydroxylammonium chloride was obtained after 18 s reaction at the flow rate of 50 mm/s in large microchannels (500μm in width) in the suggested microfludic reactors. In comparison, only 20% conversion was obtained in the conventional reactors with Y inlet.In the chapter 5, Edman degradation reaction was carried out in microfluidic chip packed with C18 beads as reaction cartridge, which was automatically manipulated by a sequential injection system. The program for sequential injection system, the column material for adsorption of protein or peptide and the temperature for Edman degradation reaction were optimized. Experiment results showed that the N-terminal residue of protein or peptide can be obtained by Edman degradation in microfluidic chip with the advantages of faster reaction rate, less consumption of protein or peptide.
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