Supercritical Carbon Dioxide Extraction of a Biaryl from Model Product Solutions of a Flow Suzuki–Miyaura Coupling Reaction

抄録

The present study investigates the extraction of a target chemical, 4-cyanobiphenyl, from model product solutions of a flow Suzuki–Miyaura coupling reaction. Fast flow extraction from an ethanol aqueous solution of 4-cyanobiphenyl was conducted using supercritical carbon dioxide as the extraction solvent under conditions of 40–60°C and 10–20 MPa. More than 80% of the 4-cyanobiphenyl was recovered in the CO₂-rich phase, and the rate was greater than 5.0 g-4-cyanobiphenyl/h for the extraction at 60°C and 20 MPa from the model solution containing salts. The effects of the ethanol mole fraction and the extraction pressure were also investigated to elucidate the effect of changes in the solvent properties on the partitioning behavior. The 4-cyanobiphenyl partition coefficient decreased with increasing ethanol mole fraction and increased with increasing extraction pressure. A model that includes the effects of changes in solubility with increasing CO₂ density and ethanol mole fraction in the water- and CO₂-rich phases was developed. The model well represents the tendency of the partitioning behavior, which indicates that the CO₂ density and ethanol mole fraction in each phase are important factors governing the partitioning behavior.