Faculty and Staff
Aaron K. Vannucci
|Title:||Assistant Professor / Inorganic
Catalysis / Materials / Organic / Organometallic
|Department:||Chemistry and Biochemistry
College of Arts and Sciences
Office: HZN1 015
B.A., 2004, College of Wooster
Ph.D., 2009, University of Arizona
We design transition metal catalysts and catalytic methodologies for small molecule activations. The group focuses on transformation of organic molecules using molecular nickel and palladium catalysts. These transformations include C–C and C–heteroatom cross-couplings, deoxygenation of biomass, and C–H bond activation.
Cross-Coupling: The long term goal of my research group is to advance photoredox catalysis for the development of new reaction mechanisms and synthesis of products that are inaccessible through thermal control, including C‑heteroatom coupling and C–H bond activation. Photoredox catalysis for organic synthesis relies on light absorbing molecules to convert visible light into chemical energy using single-electron transfer events. In particular, dual photoredox catalysis utilizes these single-electron transfers to activate a secondary transition metal catalyst for small molecule activation and bond forming reactions. Dual photoredox catalysis is currently revolutionizing cross-coupling catalysis with new methodologies for C–C bond-forming reactions. These methodologies involve mechanisms where carbon-based radicals are formed and subsequently coupled to form C–C bonds. Directly translating this radical-based reactivity for C–H bond activations and carbon-heteroatom cross-coupling has yet to be realized. Our group is working on the need to develop an efficient and direct C-heteroatom cross-coupling methodology to further fundamental organic synthesis and gain synthetic access to important classes of organic compounds.
Biomass Conversion: The lignocellulose component of biomass is typically comprised of three parts, cellulose (40-50% by weight), hemicellulose (25-35%) and lignin (15-20%). The lignin component of lignocellulose is typically treated as a waste component. However, the catalytic depolymerization of naturally occurring lignin results in a variety of oxygenated monomers that include, but are not limited to, phenol, benzyl alcohol, benzoic acid, benzaldehyde, and various ketones. The presence of these oxygenated substituents decreases the energy density of lignin, thus hindering the ability to use lignin effectively as a fuel. The high oxygen content also leads to instability and inherent difficulty to store oxygenates, which represents a major challenge in the ability to use lignin as a renewable chemical feedstock. Our group has focused on the design and synthesis of catalysts able to selectively deoxygenate lignin monomers without over-hydrogenation of the aromatic rings. First generation catalysts from our lab have exhibited excellent catalytic activity towards model lignin monomers, with the complete selectivity towards hydrodeoxygenation, even at room temperature.
DeLucia, N. A.; Das, N.; Overa, S.; Paul, A.; Vannucci, A. K. “Low Temperature Selective
Hydrogeoxygenation of Model Lignin Monomers from a Homogeneous Palladium Catalyst”
Catal. Today 2017. DOI: 10.1016/j.cattod.2017.05.050.
Paul, A.; Smith, M. D.; Vannucci, A. K. “Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings” J. Org. Chem. 2017, 82, 1996. DOI: 10.1021/acs.joc.6b02830.
Salapage, S. R.; Paul, A.; Banerjee, T.; Hanson, K.; Smith, M. D.; Vannucci, A. K.; Shimizu, L. S. “Structure, Electrochemistry and Photophysical Properties of an Exocyclic Di-Ruthenium Complex and its Application as a Photosensitizer” Dalton Trans. 2016, 45, 9601. DOI: 10.1039/C6DT01377E.