Electroorganic synthesis in an E3P reactor: Oxidation of secondary alcohols.

The aim of the present work is to investigate the use of a new type of reactor for electroorganic synthesis. The concept of this reactor is based on the principle of the porous pulsated percolated electrode (E3P) which was primarily developed for commercial use for metal recovery in waste waters. This reactor is fitted with a three-dimensional electrode of axial configuration consisting of ordered stacks of discs of expanded metal. It can be supplied by either a homogeneous electrolyte or an emulsion generated by an external ultrasonic system. The pulsation of the electrolyte represents a very effective means of improving mass transfer rates at the electrode. Under two-phase conditions, the role of the pulsation is also to ensure the hydraulic transport of the emulsion and to increase the three phase contacts between the aqueous phase, the organic phase, and the electrode. The efficiency of the reactor was tested using both homogeneous and two phase liquid-liquid electrolytes in the indirect electrooxidation of cyclohexanol and other secondary alcohols by the inorganic I+/I- mediatory system. This study reports the effects of the pulsation on the chemical and faradaic yields, as well as on the selectivity of these reactions. Optimal operating conditions are determined by factorial design. The overall results clearly demonstrate the versatility of this reactor in the field of electroorganic synthesis.