(482f) Electro-Enzymatic Cascade for Hydroxylation of Ethylbenzene

Carbon-hydrogen bond functionalization plays a pivotal role in organic synthesis and the pharmaceutical industry. Chloroperoxidase (CPO)-catalyzed oxidation of C-H bonds provides a promising alternative, offering the advantages of mild reaction conditions and excellent selectivity. However and unfortunately, the industrial application of CPO is hindered by its poor activity and stability in organic solvents and in the presence of high concentration hydrogen peroxide (H₂O₂).

The present work proposes an innovative electroenzymatic cascade for hydroxylation of ethylbenzene. An electrolytic cell reactor was assembled, in which H₂O₂ is generated via electrochemical reduction of oxygen and utilized by CPO for the oxidation of ethylbenzene. The the impacts of H₂O₂ generation rate, reducible substrates, and oxygen-containing free radicals on the stability of CPO were examined, respectively. To address the poor availability of ethylbenzene, due mainly to its low aqueous solubility, CPO was conjugated with an amphiphilic polymer, Pluronic F127, so to positioning CPO-F127 conjugate at the oil-water interface, so to enable direct access of ethylbenzene to CPO from organic phase whereas H₂O₂ diffuse to the active cite of CPO from aqueous phase. Experimental results demonstrated the workability of this novel electro-enzyamatic cascade and indicated further efforts towards enhancing reaction outcome.