Understanding mixing characteristics and influence of flow behavior on mass-transport is critical to enhancing performance in reactive flows, where the interaction between fluid dynamics and chemical reactions is important. As a model reactor system, the Taylor-Couette Reactor (TCR) allows for examining a range of hydrodynamic instabilities, while stimulating vortex motion, offering a highly active extensive interface for mass transfer, and multiphase mixing. Specifically, this dissertation assesses the effect of changing flow structure and mixing patterns in TCR on mass transport, for a range of multiphase flow reactions including crystal formation, particle functionalization and gas-liquid absorption. Overall, this dissertation confirms that it is not just the increase of energy of dissipation that is critical towards enhancing the mixing but rather the structure of the flow regimes, which if elaborately understood and characterized, enable us to exercise more effective control over the mass transfer in a reaction. The first part of this work focused on studies involving the precipitation of barium sulfate revealed that the emergence of vortex motion plays a critical role in fine-tuning crystal properties such as particle size. The second part focused on examining the influence of the onset of the primary Taylor vortex instability, as well as secondary instabilities, in tailoring the coating layer during the surface modification of metallic filler particles with methacryloxypropyltrimethoxysilane (MPS). The surface of aluminum fillers was modified with specific (H2C=C) functionality, offering a more uniform degree of coating, lower degree of aggregation, smoother surface and higher MPS coupling efficiency after the emergence of Taylor vortices, especially after the onset of modulated wavy vortex flow regime. The last part focused on investigating the variety of flow patterns in a three-phase system, reacting gaseous carbon dioxide (CO2) with aqueous calcium hydroxide (Ca(OH)2) to precipitate solid calcium carbonate crystals (CaCO3) in a TCR, to assess the influence of the corresponding flow dynamics, CO2 gas bubble size and interfacial area on the properties of the resulting CaCO3 crystals. It was found that identifying the emergence of the "ring flow" structure was critical to optimizing the interfacial area and fine-tuning crystal properties such as internal crystal pore structure, surface area, particle size and morphology.