Progettazione e preparazione di nuovi materiali per applicazioni sostenibili in chimica organica e ambientale

In recent years Green Chemistry has become a central area of research for chemists working in both industry and academia. The fundamental concepts of sustainable chemistry are, among others, atom efficiency, waste prevention, use of renewable materials and innocuous solvents, as well as design of safer products. Within this context, microreactor technology offers, on the one hand, safe, environmentally benign, and high throughput processes typically intensified by a fast postreaction phase (workup and purification) and direct scalability; on the other hand, asymmetric organocatalysis allows for new and unique opportunities towards efficient and highly stereoselective metal-free catalytic syntheses. In the first part of this thesis project it has been carried out the synthesis of new heterogeneous organocatalysts for their ultimate utilization in continuous-flow processes. Precisely, proline-like mimetics and thiazolium salt pre-catalysts have been immobilized on silica and polystyrene macroporous supports, respectively; next, these functionalized solid materials have been employed as packing material for the fabrication of fixed-bed microreactors in the form of either packed or monolithic columns. During this research, it has been demonstrated that operation of this type of organocatalytic microreactors results in flow processes with levels of stereoselectivity comparable to those of the corresponding homogeneous batch processes, allowing at the same time productivity enhancements thanks to the higher long-term stability of the heterogeneous organocatalytic species in flow regime. In the second part of this thesis project, the same techniques of support functionalization have been employed to prepare perfluorinated stationary phases for the determination of perfluorinated compounds (PFCs). These are emerging pollutants widely spread in the environment. They can be found in soils, sediments, superficial waters, particulate matter, as well as in animal and human tissues or organs. PFC are characterized by environmental persistence and have negative side effects for the biota where they accumulate. The chromatographic behavior of perfluorinated acid pollutants have been investigated on the basis of the specific fluorine-fluorine interactions (fluorophilicity) occurring between these analytes and the perfluoroalkyl groups of the newly prepared stationary phases. It has been demonstrated that the retention profile of perfluorinated acids is dependent on the composition of the mobile phase, thus permitting the use of the prepared fluorinated stationary phases as means of pre-concentration of PFCs from environmental and biological matrices.