Electrochemical generation of highly reactive nickel and its utilization for organic reactions

A highly reactive nickel powder like Rieke's nickel can be prepared by electrolysis of a DMF solution containing 0.3 mol.dm(-3) Bu4NBF4 or 0.3 mol.dm(-3) Et4NBF4 in an undivided cell with a platinum cathode and a nickel anode without massive deposition onto the cathode at a constant current of 10 mA/cm(2) at 0 degrees C under an argon atmosphere. The transmission electron micrograph of the electrochemically generated nickel powder shows the particle size to be 2-3 nm. The Ullmann-type reaction of aryl halides with the reactive nickel proceeded with approximately the same yields as those using Rieke's metal. Therefore, the electrochemically generated nickel pow der has enough activity for reduction of nitrobenzenes and deallylation of allyl aryl ethers. These reactions proceeded without affecting various functional groups at room temperature in a short reaction time.