Continuous high-pressure operation of a pharmaceutically relevant Krapcho dealkoxycarbonylation reaction

The synthesis of the pharmaceutically relevant scaffold 3,4-dihydro-1H-1-benzazepine-2,5-dione via Krapcho dealkoxycarbonylation in a continuous high temperature high pressure coil reactor is investigated and compared to results from batch experiments. In a first step, the continuous reactors residence time distribution (RTD) is characterized, followed by an initial comparison of batch and continuous reactant conversion profiles indicating a very good agreement between both reactors by means of conversion time. Reaction temperature is increased above the solvents atmospheric boiling point in the continuous reactor system to intensify the reaction and increase throughput. Optimal reaction parameters for complete conversion of the starting material in 3 min reaction time were estimated based on batch kinetics and confirmed by a continuous experiment. The system is able to generate around 12.2 g product per day.