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Bromine-lithium Exchange Reaction in Organic Synthesis Using Glass Microreactor

Zeibi Shirejini, Saeed Reza | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48211 (01)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mohammadi, Aliasghar
  7. Abstract:
  8. Today, microreactors come into focus due to their exclusive characteristics including high surface-to-volume, lower consumption of reagents and fast mixing. In this study, optimization of the Br-Li exchange reaction as a consecutive reaction using glass microreactor is investigated. To construct glass microreactor, laser ablation and thermal bonding method are utilized. In order to find the best yield and selectivity of the reaction, various parameters, such as solvent, equivalent ration of the two reagents, concentration of the reagents, residence time and flow rates of the reagents are examined. In addition, atomic force microscopy (AFM) analysis was used to determine the surface characteristics of the glass before and after thermal annealing. Furthermore, to inspect the efficiency of the thermal bonding method, the cross-sectional picture of the abated microchannels is investigated. Our results delineate that thermal fusion bonding is an appropriate method to construct microfluidic devices so that no clogging and distortion of the microchannels was observed after thermal annealing. Moreover, results demonstrate that by using co-solvent system of hexane-THF by the volume ratio of 15:1, the highest yield and selectivity of the reaction can be achieved. In addition, the use of 1.2 equivalent ratio of n-BuLi results in the best yield of the reaction. The results illustrate that as the concentration of the reagents increases, the rate of the reaction increases which results in higher yield and selectivity of the reaction. Residence time investigation results reveal that microreactor provides a condition under which fast mixing is occurred and therefore, the yield and selectivity of the reaction are higher than that of batch systems. Finally, it is worth to note that as the flow rates of the reagents increases, the yield of the reaction increases. This is mainly due to the fact that by increasing the flow rates mixing rate increases which results in higher yield
  9. Keywords:
  10. Laser Ablation Process ; Glass Microreactor ; Bromine-Lithium Exchange Reaction ; Fast Mixing ; Thermal Fusion Bonding

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