degradation. This can be done by extracting the product into a solvent and thus avoiding the acidic conditions. Another effective approach is to run the process in a continuous flow, where the temperature can be rapidly increased and after the acid catalyzed reaction has taken place, rapidly lower the temperature. Ideally, you also want to remove the acid to further mitigate the conditions.
1.2.2
Method
Flow chemistry The concept of "flow chemistry" defines a very general range of chemical processes that occur in a continuous flowing stream, conventionally taking place in a reactor zone. The application of flow chemistry relies on the concept of pumping reagents using many reactor types to perform specific reactions. The most common types of reactors are plug flow reactors and column reactors, whilst for specific chemistries more sophisticated reactor designs might be needed (e.g., photoreactors, electrochemical reactors, etc). There are well-defined key advantages using flow technologies as compared to standard batch chemistry methods: -
Improved heat transfer Improved mass transfer/mixing Improved kinetics Heterogeneous reactions are easily managed Reproducibility Scale-up Extreme reaction conditions (high/low temperature, high pressure) Multistep (telescoping) In-line downstream processing Automation Improved Safety (managing hazardous reagents and intermediates)
In this work package, many of these advantages are being utilized, e.g. improved mass transfer, high temperature and pressure and benefits from increased catalyst loading in heterogeneous reactions. In addition to these and as mentioned before, the ability to transport the formed product away from the acidic environment aids in reducing degradation. An apparatus specifically designed for flow chemistry was used in this WP [ref Uniqsys]. A modified column compartment allowed for higher temperatures (up to 200 ˚C) to be used. In addition, the heating module was modified to allow for even higher temperatures (up to 350 ˚C). Several catalysts and conditions were evaluated for the efficient production of HMF. Previous reports (Daorattanachai, et al 2012) have shown that a Calcium-Phosphate catalyst has produced interesting results in both rearranging glucose into fructose and to convert fructose into HMF.
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