Catalysis in complex media: Analytical approaches and mechanisms in manganese catalysed oxidations

Over recent decades, mechanistic studies in manganese catalysed oxidation catalysis in organic solvents has provided a broad insight into the mode of action of the catalysts and various parameters that control the outcome of the catalysis. However, understanding the behaviour of these catalysts in complex aqueous media has received much less attention due to the analytical complexity of these systems. The catalysis systems based on manganese salt and the tmtacn ligand with hydrogen peroxide is a typical example. Mn-tmtacn based catalysts have been applied in bulk catalysed oxidation processes, e.g., raw cotton bleaching as well as domestic cleaning. In this thesis, the aim was to understand at a molecular level, how and why these Mn-tmtacn base catalysts work in complex aqueous media and develop the necessary analytical techniques to probe such complex systems. A solid mechanistic understanding of the effect of additives, buffers, pH and oxidation state of the manganese catalysts was established through these studies. In addition, the research described in the thesis focused on novel analytical methods for handling complex reaction mixtures. The application of the DCDR (drop coating deposition Raman) method in the analysis of reaction mixtures during (organic) synthesis and to monitor the progress of catalysed reactions was explored. Although, DCDR spectroscopy has seen recent application in the study of biological fluids, its application in other areas was not explored. A key advantage of using this method to monitor the catalytic reaction is that the rapid drying of the sample in this method results in quenching of the reaction, which allows for analysis after the reaction at a later time.