Smarsly, Bernd M.Schreiner, Peter R.Ali, UsmanUsmanAli2026-01-192026-01-192025https://jlupub.ub.uni-giessen.de/handle/jlupub/21215https://doi.org/10.22029/jlupub-20560Sustainable organocatalysis requires heterogeneous catalytic systems that are efficient, reusable, and aligned with the principles of sustainability. This thesis explores two complementary materials aimed at achieving this balance: the rational engineering of hierarchically porous silica monolith support and the utilization of renewable chitosan biopolymers as solid catalysts. Together, these studies illustrate how rational control over material structure and intrinsic functionality can be harnessed to simultaneously enhance catalytic performance and align with environmental sustainability. In Publication 1, the focus was on the structural evolution of mesoporosity in hierarchically porous silica monoliths prepared by the Nakanishi method. The study placed particular emphasis on advanced physisorption analyses using argon (87 K) and nitrogen (77 K), complemented by hysteresis scanning, to unravel the development of the mesoporous network under varying hydrothermal treatment temperatures (HTTs). These analyses revealed a systematic expansion of mesopores (8 to 25 nm) while maintaining constant pore volume, indicating a dissolution-reprecipitation mechanism that governs mesopore formation and connectivity. The work provided fundamental insights into how hydrothermal conditions shape mesoporous network, diffusion, and accessibility, establishing design principles for tailoring monoliths for catalytic and separation applications. In Publication 2, chitosan was studied as a renewable heterogeneous organocatalyst for Knoevenagel condensations among various benzaldehydes and ethyl cyanoacetate. High yields were achieved under mild conditions, with efficient catalyst and solvent reuse across multiple cycles. Importantly, the study demonstrated that renewability alone is not enough; optimization of overall process through mild conditions, energy efficiency, and recyclability can make a genuine impact on sustainable synthesis. The approach was successfully optimized to the gram-scale synthesis of an Atorvastatin intermediate, underlining its practical relevance. Together, these publications highlight two distinct but complementary strategies: the controlled engineering of pore structures in silica monoliths for applications such as continuous-flow catalysis and the dynamic functionality of chitosan as a green catalyst. Both approaches contribute to the broader goal of developing efficient, robust, and truly sustainable organocatalytic systems.enAttribution-NonCommercial 4.0 InternationalChitosanOrganocatalysisPorosityPhysisorptionSustainabilitySilica Monolithsddc:540