Nicholas, KennethMcClain, James Michael II2015-02-272015-02-272015-02-06http://hdl.handle.net/11244/14229Sustainable and renewable carbon sources are of great interest for long term succession of humankind. The sugars and polyols derived from cellulosic biomass offer such a sustainable feedstock considering cellulosic biomass is the largest carbon commodity on Earth. Selective deoxygenation of these sugars and polyols may well provide a feedstock for the synthesis of fine chemicals and fuels. Deoxydehydration (DODH) is one of the selective deoxygenation methods for upgrading sugars and polyols to higher energy alkenes using an oxometal catalyst and a stoichiometric reductant. In this report several aspects for the oxorhenium catalyzed DODH of polyols are examined. An alternate realm of reductants are introduced for the oxorhenium catalyzed DODH of glycols. The commercially available ammonium perrhenate (APR) is employed along with zero-valent elements zinc, iron, manganese, or carbon as reductant for the effective DODH of various glycols. These elemental reductants and their oxidized products remain heterogeneous in the reaction mixture allowing for their simple separation. Stable, ligated, cationic dioxorhenium(V) compounds of the form RevO2Ln+ are demonstrated to be proficient pre-catalysts for the DODH of glycols with assorted reductants. The tetrapyridine dioxorhenium(V) complexes [ReO2py4]Cl and [ReO2py4]PF6 (py = pyridine) are demonstrated to be proficient pre-catalysts for the DODH of glycols with sodium sulfite, zinc, and benzyl alcohol (BnOH). In addition, the commercially available bis-triphenylphosphine(TPP) iodo dioxorhenium(V) complex (ReO2(TPP)2I) is established to be capable of BnOH driven DODH of glycols. Mechanistic aspects of [ReO2py4]+ DODH of glycols with BnOH are probed. There is an apparent second order dependence on the oxorhenium complex. This second order dependence on rhenium is attributed to a bimolecular turn over limiting step involving one rhenium coordinating and activating BnOH for reduction of the second rhenium which has been oxidized through alkene extrusion from a rhenium-glycolate. The DODH reaction is also found to have a negative pseudo-order in the glycol and is attributed to inactive polyglycol rhenium species. The addition of catalytic concentrations of additional ligands such as pyridine or triphenylphosphine oxide accelerate the reaction and are likely involved in shifting the equilibrium towards the rhenium monoglycol and away from the polyglycol.Chemistry, Inorganic.