Safety Improvements of a Grignard Reaction by Controlling the Reactant Feed Rate by On-line Concentration Monitoring Using NIR

Grignard reactions are often highly exothermic and are performed near to or at the boiling point of the solvent. Therefore, a detection of the initiation of the reaction based on temperature measurements is in many cases difficult in the industrial environment. A delayed initiation of the reaction can lead to an unsafe situation (overpressure in the reactor system). This paper describes the automated monitoring of the reactant feed rate to avoid any excessive reactant accumulation. The concentrations of the substances are determined on-line using NIR spectroscopy, and these data are used to control the feeding pump. The equipment used for this purpose is the same type as that used in production plants. Therefore, the transfer of this technology to a manufacturing plant is facilitated. The automation of chemical processes leads to safety improvement, increase of the plant efficiency, and reduction of the operating costs.