Continuous flow synthesis in micro/meso-scale reactors (channel diameters below 1000 m) offers several distinct advantages over traditional batch reactions and is a key-method for ?Process Intensification?. In flow devices, equipped with a back-pressure regulator, reactions can be performed at temperatures far above the boiling point of the solvent and, thus, reaction times often can be dramatically reduced. Furthermore, the small internal volumes and high surface-to-volume ratios of microreactors enable exceptionally fast heat and mass transfer. Therefore, the reactivity of reactants and reagents can be fully exploited without mass transport or dissipation of heat becoming limiting. The shorter reaction times at high reaction temperatures allow a reduced reactor size for a given throughput and a safer and more economical overall process.In the present thesis, scalable continuous flow processes for the synthesis of industrially relevant compounds were developed. Many of the reactions presented herein involved toxic, explosive or highly reactive reagents/intermediates. Since the volumes processed at any time are very small for flow processes in microreactors, safety issues and process challenges associated with reactions involving reactive or otherwise hazardous materials are reduced. Despite the small volumes of these devices, however, production scale capacities still can be achieved by continuous processing and various scale-up methods. Furthermore, the synthetic transformations were often performed under reaction conditions which would be difficult to reproduce in traditional batch equipment ("Novel Process Windows"). Thereby, reaction times could often be significantly reduced compared to the traditional batch processes.Mechanistic aspects of the presented transformations were investigated experimentally and, in some cases, further studied by computational methods.