Date of Award
12-23-2014
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Applied Science
First Advisor
Anindya Ghosh
Abstract
Use of carbon dioxide (CO2) for the production of industrially important organic compounds has drawn great deal of attention in recent years, especially in terms of sustainable development based on green chemistry. The use of CO2 as a starting material may replace several toxic C1 synthons such as isocyanates, phosgene etc. Among many reactions involving CO2, synthesis of cyclic carbonate using epoxide under catalytic conditions has drawn major attention. Cyclic carbonates are odorless, colorless, biodegradable solvents which have found several applications as polar solvents, electrolytic material and precursor in the production of polycarbonates as well as pharmaceutical chemicals. However, elevated thermodynamic stability of CO2 has limited the current industrial use of CO2. In order to overcome its inertness, several transition metal catalysts have been developed over the years that are capable of converting CO2 into useful chemicals. In this dissertation work, we present our studies on the use of cyclic and acyclic amide based transition metal complexes for the catalytic transformation of CO2 towards the synthesis of cyclic carbonates from epoxides or olefins under mild reaction conditions. A series of amide based metal complexes were synthesized and characterized using various spectroscopic techniques. Reactions were performed under solvent-free condition and in the presence of a Lewis base, which acts as a co-catalyst. Important reaction parameters such as pressure, temperature and variation of co-catalyst to catalyst ratio were studied in order to obtain an optimum reaction condition. Activity of Co(III) metal complexes with various electron withdrawing and electron releasing substituents on the ligand moiety were studied and electron withdrawing group containing complexes showed exceptionally high catalytic activity. We also present one-pot conversion of olefin to cyclic carbonates using a novel manganese complex. Manganese amidoamine complex and tetrabutylammonium bromide were found to form an efficient catalytic system for the epoxidation of olefin and further cycloaddition of CO2. The presence of a primary oxidant such as tert-butylhydroperoxide is essential for the conversion of alkene to epoxide catalyzed by manganese complex. The effects of reaction temperature, oxidant, as well as substrate on the yields of cyclic carbonate were investigated, and the reaction mechanism was established.
Recommended Citation
Ramidi, Punnamchandar, "Amide Based Metal Complexes for the Catalytic Transformation of Carbon Dioxide to Cyclic Carbonates" (2014). Theses and Dissertations. 551.
https://research.ualr.edu/etd/551
