MARINE MOVSISYAN, THOMAS S. A. HEUGEBAERT, CHRISTIAN V. STEVENS*
*Corresponding author
Ghent University, Department of Sustainable Organic Chemistry and Technology,
Ghent, Belgium

Abstract

Highly reactive compounds in chemical production are both a blessing and a curse, as they allow fast and efficient conversions, but in the same time severely challenge reaction control, safety and equipment, to the point that some of these reactions cannot be conducted via  conventional processing methods. Slowly but steadily, continuous flow technology is earning its place in the chemical industry as a technique for process intensification due to its superior reaction control. More and more, these advantages are applied to conduct hazardous chemistry, with its hazards well contained and controlled within a closed microreactor system. The possibility for on-site and on-demand synthesis of reactive intermediates coupled to direct conversion to stable end products avoids storage of and exposure to these harmful compounds. The focus on safety does however not imply that selectivity and throughput are secondary criteria. On the contrary, a shift to more ambitious territory is visible, where integration of hazardous chemistry and scalability via continuous flow technology is becoming industrial practice. The modularity of continuous flow systems enables a straightforward and rapid upscaling with guaranteed safety and without the need for time-consuming re-optimisation. Recent publications on continuous flow possibilities of hazardous chemistry on scale will be discussed, followed by an experimental study for the generation and consumption of labile acid chlorides in situ.

INTRODUCTION

Continuous flow technology has conclusively proven to offer an alternative methodology to perform chemistry. Microstructured devices are known to enable a higher level over control of the reaction parameters, which results in a higher selectivity and an increase in process efficiency and safety. These characteristics open the path to tackle unexploited or even forbidden chemistries in a contained and controlled system. The ultimate objective is to make each type of chemistry accessible for both lab-scale and industrial applications, regardless of the type of equipment and in line with more intensified, safer and environmentally friendly processes. Chemists can be persuaded by the added value of microfluidic systems when considering specific chemistries and the practical features of a process.

Safety and selectivity issues, inherent to the reactive and hazardous nature of reactants and intermediates or the kinetics or thermodynamics of a process, are the main causes to abstain from hazardous chemistry. The  use of various “forbidden” materials has been limited or even averted, especially for scale-up purposes, and has been replac ...