Catalytic CO2 Cycloaddition with Epoxides into Cyclic Carbonates: Synergies from Computational to Experimental Studies

Identifier:  TDX:3208

Handle: https://hdl.handle.net/20.500.11797/TDX3208

Authors:  Yeamin, Md Bin

Abstract:
CO2 utilization as a chemical feedstock has been proven as a major strategy to reduce CO2 emissions to the atmosphere, and therefore to find an equilibrium in the natural carbon cycle. However, activating this stable small molecule is very challenging. In fact, high internal energy-containing reactive substrates can facilitate chemical transformations of CO2 to compensate its thermodynamic stability. Moreover, efficient catalysts are needed to overcome the high kinetic barrier of activation. Among many catalytic methods, thermal catalysis is still the mostly used method to scale up the CO2 fixation processes at industrial level. Catalysts with higher activity and selectivity in milder reaction conditions are required. Therefore, we aim to assess the efficiency of low-cost earth-abundant materials as catalysts for CO2 cycloaddition with high energy-containing epoxides. We also aim to understand the behavior of these catalysts from computational mechanistic studies, and to improve on their design corroborating with their experimental catalytic performance for this CO2 transformation reaction. In this Thesis we study three different catalysts for CO2 cycloaddition reaction with epoxides under thermal gradient. The catalysts are lignocellulosic biomasses as most abundant plant materials, 1,10-phenathronine derived four nitrogen donor containing complexes of zinc, and a cyclam derived complex of the most abundant element iron. The cooperative effects of these binary catalysts in combination of a co-catalyst, tetrabutyl ammonium bromide (TBAB) are elucidated from computational mechanistic studies. In experimental studies, the catalytic reactions are optimized for standard substrates, and %substrate conversions are corroborated with the activation energy barriers from reaction mechanisms, where applies. Also, the nature of different catalytic active sites is analyzed from substrate scope standpoint.