Continuous Flow Aerobic Oxidation Reactions using Heterogenous Catalyst
Alain Favre-Reguillon, Associate Professor, University of Lyon
In recent years, catalytic aerobic oxidation reactions
in the liquid phase have become an important topic, driven by the need for
reaction technologies that can be employed for biomass conversion, and for more
sustainable processes for the fine chemicals and pharmaceutical industries. In
terms of process safety and control, it is widely acknowledged that aerobic
oxidation reactions are best implemented in continuous flow.
Arguably, one of the most challenging reactions is the
selective oxidation of alcohols to aldehydes and ketones, a process that is
ubiquitous in organic chemistry. However, it is still one of the least
efficient, engendering the development of a large number of methodologies. Ruthenium-based
heterogeneous catalysts exhibit a broad substrate scope, including tolerance to
heterocycles and other functional groups commonly encountered in pharmaceuticals
and fine chemicals and was adapted in flow.
Furthermore, in a flow regime, the longevity of a
catalyst is a major determinant of its economic viability. Therefore, it is important
to understand how catalyst activity (TOF) is affected by reaction parameters
like temperature, O2 pressure, gas/liquid flow rates, solvent
effect, alcohol concentration as well as deactivation mechanisms. Our recent
results on continuous flow aerobic oxidation reactions using Ru/Al2O3
will be presented and also compared to Cu/TEMPO homogeneous catalytic system.
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