University of Minnesota
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Topczewski Group

Research Overview: Sustainable Synthesis - Metrics, Innovations, and Catalysis

The fundamental goal of the Topczewski lab is to make chemical synthesis sustainable. Presently, consumer products, which range from plastic bottles to modern pharmaceuticals, are almost exclusively derived from the arduous refining of petroleum. This is inherently unsustainable and two approaches exist to bridge the sustainability gap: 1) to develop more efficient ways to use dwindling fossil fuels and 2) to develop methods to sustainably use biomass as a feedstock for chemical synthesis. For either of these approaches to make an impact, one must qualify what is meant by “more efficient” and “sustainable.” This necessitates the use of quantitative metrics to be used as a guiding principle. To these ends, a number of projects are underway:

Direct Synthesis of Chiral Amines:

Chiral amines are a fundamental motif present in amino acids, amino sugars, ligands, materials, natural products, and pharmaceuticals. The synthesis of chiral α-substituted amines has been extensively studied and a variety of methods are available for their production. In stark contrast, there is a clear scarcity of methods available for the synthesis of chiral α,α-disubstituted amines.  Most of these methods require the covalent attachment of an auxiliary either to attenuate reactivity or selectivity and are thus inherently inefficient. This project aims to prepare chiral α,α-disubstituted amines via direct catalytic methods from readily available feedstocks.

The Development of Novel Feedstock Conversions:

Petroleum is the dominant feedstock in the chemical industry’s annual production of tens of millions of tons of plastic and other products (ca. 2 x 1011lbs/year). Although some of these syntheses are very efficient, there are two fundamental problems with this production: 1) the reliance on diminishing supplies of oil or other nonrenewable feedstocks and 2) the large quantity of end-of-life consumer waste (i.e. empty drink bottles or food wrapping). This project focuses on addressing both of these issues by directing the power of modern catalysis towards developing new methods for feedstock utilization and in developing ways to recover useful chemicals from end-of-life consumer waste. Examples of this work would be the conversion of plant-based lactic acid to renewable (now petrol-based) acrylic acid, conversion of furfural (plant-based) to new materials or methods to convert waste plastic (polystyrene or PLA) to new monomers.

Metric Utilization and Development:

The past several decades have seen a tremendous advance in the power of synthetic methodology to deliver complex molecular architectures via highly selective and high yielding processes. However, the yield (most common metric) of a chemical process does not necessarily correlate to the efficiency of that process – especially when all reagent inputs are considered. When methods fail to reach the ideal, metric based analysis will identify the “sustainability-limiting factor” and thereby inform subsequent methodological improvements to ensure new methods are impactful. The aim of this project is to understand the state of synthetic efficiency by studying the methods used in key bond forming steps (i.e. biaryl formation) and accounting for all of the inputs used in those steps. When inputs are comparable, this is a trivial comparison (3 equiv. < 1 equiv. < catalytic amounts of same reagent). However, when dissimilar choices must be made the impact is non-obvious (i.e. impact of solvent vs base choice vs catalyst loading) and no currently used metrics are available to correlate these dissimilar choices.