The mesoscale oscillatory baffled reactor facilitates intensified kinetics screening when the solvent is removed

Abstract

There are numerous potential benefits of conducting chemical reactions in the absence of solvent. For instance, the risk of environmental release of the solvent is eliminated and there is the potential for intensification via increased reaction rates reducing the required reactor volume. It was previously shown that two configurations of the mesoscale oscillatory baffled reactor (heat pipe and jacketed) could address the challenge of performing exothermic reactions without a solvent, by removing or spreading out the heat released. This could lead to a new approach in green chemistry. Here, this concept was extended to reaction kinetics screening from the same exothermic imination reaction conducted without a solvent. The effects of up to three operating variables (residence time, reactant molar ratio and temperature) were screened in a single flow experiment. It was found that both reactor configurations were able to obtain the Arrhenius kinetic parameters: activation energies of 103.98 ± 3.79 kJ/mol and 98.11 ± 1.55 kJ/mol, respectively, for the two imine synthesis steps. This demonstrated that meaningful data could be obtained, even though the solventless reaction medium was changing as a function of the reaction. Other benefits of this green chemistry approach include: high reaction rates/throughputs, reduced preparation time and reduced downstream purification requirements.