Cobalt(II) diacetylmonoxime complex-catalysed oxidative coupling reactionsof few aromatic compounds

Catalytic amount of a diacetylmonoxime cobalt(II) chloride complex [A] alon g with hydrogen peroxide reacts with toluene to give benzylalcohol, benzald ehyde and trace amount of p-cresol and o-cresol. Similar catalytic reaction of aniline gives C-N-bonded oligomer having M-n and M-w. of 1256 and 1892, respectively, Mass spectra determined by MALDI suggests the polyaniline to have highest mass from 14 units of aniline with CoCl2 unit attached at thr end. The oligomer thus formed have semiconducting proper ties. Similar rea ction of phenol with cobalt(II) diacetylmonoxime (Co-DAM) complex in the pr esence of hydrogen peroxide gives C-O-bonded polyphenol. The reaction of 2- aminophenol with [A] and hydrogen peroxide leads to aggregate that has prop erty of irreversible thermoelectric sensor. ESR suggests this property to o riginate from free radical present in the aggregate. Substituted aniline su ch as 2,4-dimethoxyaniline can also form low molecular aggregate from simil ar reaction that has semiconducting property in the range of 35 degrees C-1 80 degrees C. (C) 2000 Elsevier Science B.V. All rights reserved.