The Liquid Phase Oxidation of 1, 2, 4, 5-Tetramethylbenzene with the Transition Metal-Bromide Catalysts in Acetic Acid

Abstract

The liquid phase oxidation of 1, 2, 4, 5-tetramethylbenzene (TeMB) with oxygen in acetic acid using transition metals and bromide as catalysts was studied.
The activities of metals for the oxidation of TeMB were in the following order, Co Ni Cr Mn in the absence of bremide and Co.. Mn Ce Cd Ni ig Cr in the presence of bromide and the activities of Hg, Pb, Cd, , Ag and Zn were not observed. The activity of cobalt catalyst was found to increase by a factor of seven in the presence of bromide. Bromide ion used as a catalyst was entirely converted to, or. ganic. bromide. at., the initial stage of oxidation, .. when the. rate of oxygen absorption reached the highest.
Results on the time dePetiderice of the compositioh of oXidation products made clear that the oxidation of TeMB was proceeded according to the succesive reaction and the ratio of the distribution for, dicarboxylic acidisomers, 4, 6-dimethylisophthalic, 2, 5-dimethylterephthalic and 4, 5-dimethylphthalic acid, at the steady state of oxidaption, was 48: 28: 24.
In the oxidation of TeMB at 10 kg/cm2 of oxygen pressure, the rate and the extent of oxidation increased as compared with the atomospheric reaction. However, the activities of catalyst were almost unchanged as well as the nature of reaction.