Controlling reaction rate of phase transfer hydrogenation of
acetophenone by application of low external electric field
Abstract
The controllable mass transfer and reaction rate for phase transfer
hydrogenation of acetophenone across a well-defined boundary were
investigated. The effect of solvent was found important and 1-butanol
exhibited the best performance among the five investigated homologous
alcohol solvents, consistent with its higher solubility in water and
greater dielectric constant. Initial reaction rates increased with
increasing electric potential, consistent with enhanced mass transfer
across the aqueous/organic boundary. At longer reaction times
deactivation was apparent. It correlated with increasing voltage and is
ascribed to lower equilibrium concentration of reactive species at the
interface. External control over reaction rate was demonstrated by
switching the applied electric potential over the course of the
reaction. Effects of external electric field on enantioselectivity were
also explored with reversal field direction. The changes correlate with
catalyst decomposition.