This thesis is dedicated to continuous flow processes for the catalytic transformation of biofeedstocks into fine and speciality chemicals. Four processes, namely epoxidation and ethenolysis of a bio-waste triglyceride, reduction of artemisinin and etherification of dihydroartemisinin were developed under batch and flow conditions. First, an epoxidation reaction was studied using a modified WVI/PV/H2O2/PTC catalyst complex. The reaction proceeded with high selectivity to oleic epoxide (86 %) and high conversion (100 %) towards the epoxidation reaction in both, batch and flow systems. The enthalpy of epoxidation of cocoa butter was found to be mildly exothermic at -168 kJ mol-1. Space time yield, a key process parameter, in both the systems were similar. The epoxidation of cocoa butter was controlled under both batch and flow conditions by mass transfer and chemical reaction. Second, the ethenolysis of cocoa butter under batch conditions was optimised in terms of catalyst, solvent, temperature and pressure. The M11 catalyst proved to be the most active at room temperature and 2 bar ethylene pressure in THF solvent. The optimized system was transferred to a continuous membrane contactor system. A high yield of decene and 1,4-decadiene were achieved, 44.5 % in total, for a residence time of 59 min at 40 ℃ and ethylene pressure of 6 bar. Third, the stoichiometric reduction of artemisinin to dihydroartemisinin (DHA) was successfully transferred from batch to continuous flow conditions with a significant increase in productivity and an increase in selectivity. A DHA space-time-yield of up to 1.6 kg h-1 L-1 was attained, which represented a 42-fold increase in throughput compared to the conventional batch process. Finally, a highly active heterogeneous catalyst was found for the etherification of dihydroartemisinin to a pharmaceutical API artemether. Using the QuadraSil catalyst allowed us to eliminate one step in the reaction workup. A comparative Life Cycle Assessment of both reduction and etherification reactions showed advantages of the flow process over the optimized literature batch protocols. The results of the LCA highlight the significance of solvents in pharmaceutical manufacture and the advantage of flow technology, enabling small solvent inventories to be used.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:635608 |
| Date | January 2014 |
| Creators | Plaza, Dorota |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/66188/ |
Page generated in 0.0497 seconds