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 elec trolysis 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 parti cle size to be 2-3 nm. The Ullmann-type reaction of aryl halides with the r eactive nickel proceeded with approximately the same yields as those using Rieke's metal. Therefore, the electrochemically generated nickel pow der ha s 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.