APPLICATION OF AN ELECTROCHEMICAL PULSED FLOW REACTOR TO ELECTROORGANIC SYNTHESIS - PART-I - REDUCTION OF ACETOPHENONE

The aim of this work is to investigate the use of a new type of reacto r for electroorganic synthesis. The concept of the reactor is based on the principle of the porous percolated pulsed electrode (E3P) which w as primarily developed at commercial scale for metal recovery in waste waters. The reactor is fitted with a three-dimensional electrode, of axial configuration, consisting of ordered stacks of discs of expanded metal. It can be supplied either by a homogeneous electrolyte or by a n emulsion generated by an external ultrasonic system. The pulsation o f 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 emul sion and to increase the three phase contacts between the aqueous phas e, the organic phase and the electrode. The efficiency of the reactor was tested using both homogeneous and two phase liquid-liquid electrol ytes in the direct reduction process of an aromatic ketone. This study reports the effects of the pulsation on the mass transfer rate of ace tophenone at the electrode. A comparative study of the behaviour of th e E3P reactor towards different media is accomplished. Particular atte ntion is paid to the chemical and faradaic yields, as well as to the s electivity of the reaction.