Catalytic and electrocatalytic wet oxidation of phenol using two new nickel(II) tetraazamacrocycle complexes under heterogeneous conditions

Two new tetraazamacrocycle complexes, namely, 7,16-dinicotinoyl[Ni{Me4(4-MeBzo)2[14]tetraeneN4}] and 7,16-diisonicotinoyl[Ni{Me4(4-MeBzo)2[14]tetraeneN4}] (where [Ni{Me4(4-MeBzo)2[14]tetraeneN4}] = 5,7,12,14-tetramethyldi-4-methylbenzo[b,i][1,4,8,11]tetraazacyclo-tetradecahexaenatonickel(II)) were synthesized by acylation of [Ni{Me4(4-MeBzo)2[14]tetraeneN4}] and characterized using spectral and microanalytical data. All tetraazamacrocycle complexes were found to catalyze chemical oxidation of phenol by H2O2 to catechol and hydroquinone and it is found that 7,16-diisonicotinoyl[Ni{Me4(4-MeBzo)2[14]tetraeneN4}] showed the best performance. Catechol as the major product and hydroquinone as the minor were characterized respectively under optimal values of some parameters such as amount of catalyst, reaction temperature, oxidant and substrate concentration, effect of reaction media and reaction time. Electrocatalytic oxidation of phenol on glassy carbon electrode modified by the synthesized macrocycle complexes has also been studied.

Two new Ni (II) tetraazamacrocycle complexes have been synthesized and characterized. Their catalytic effects on electrochemical oxidation and regioselective chemical oxidation of phenol by H2O2 are also described. Effects of various parameters like temperature, amount of catalyst, amount of oxidant, effect of reaction media and time on the overall conversion as well as product selectivity have been investigated.Figure optionsDownload as PowerPoint slide