Date of Award

Fall 2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Mahdi Abu-Omar

Committee Chair

Mahdi Abu-Omar

Committee Member 1

Garth J. Simpson

Committee Member 2

Nathan Mosier

Committee Member 3

Tong Ren

Abstract

By selectively removing functional groups from biomass derived carbohydrates, valuable platform chemicals can be generated from renewable sources. Through dehydration chemistry glucose can be upgraded into 5-(Hydroxymethyl)-2-furfuraldehyde (HMF) and levulinic acid. Iron (III) chloride hexahydrate has shown moderate activity to transform glucose into HMF and has also shown high yields and selectivity for the production of levulinic acid. Typically synthesized from acidic solutions made with mineral acids, levulinic acid has now been produced in high yields with a metal salt. The difference between maximizing production for HMF or levulinic acid from the same catalyst relies on the control of the reaction conditions. By using microwave irradiation, improved collisions and stabilized transition states allow for selective production of desired products while eliminating undesired reaction pathways. ^ Understanding the improvement of biomass carbohydrates also requires understanding how they are incorporated into the plant structures. By utilizing fluorescent tagging strategies a two part marking system was used to follow the incorporation of fucose into the plant cell wall. Fucose is limited in its use by plants only becoming incorporated into branched xylan chains that help to link cellulose and hemicellulose together. The synthesis of xylan in the plant Golgi also utilizes extracellular sugar. By feeding plant cells a specially designed azido tagged sugar it should become incorporated into the cell wall. On its own, the azido tagged sugar has very little fluorescent properties; however the attached azide group becomes important for click reactions. Click reactions involve two small functional groups that selectively combine. In this case the azide is clicked to an alkyne group to form a triazole. The alkyne group is part of a naphthalimide compound that has strong fluorescent properties due to its aromatic structure. By adding a triazole to the fluorescent naphthalimide complex, a much stronger fluorescent signal can be generated. By reproducing this strategy with plant cells it was hoped that the strong fluorescent signals could be imaged after their incorporation into plants. However issues with reproducibility of fluorescent emission spectrum and only two-fold intensity differences rather than the desired order of magnitude difference proved to be experimentally challenging.

Download

Share

COinS