Terephthalic acid synthesis in high-temperature liquid water

We have completed an exploratory study of the synthesis of tereplithalic acid via the partial oxidation of p-xylene in liquid water at temperatures ranging from 250 to 350 degreesC. The reactions occurred in 1.54 mL stainless steel batch reactors, and the batch holding time was 60 min. We determined the influence of temperature, catalyst identity, p-xylene initial concentration, and oxidant initial concentration on the yield of tereplithalic acid and intermediate products. The catalysts included in this study were manganese bromide, cobalt bromide, manganese acetate, nickel bromide, hafnium bromide, and zirconium bromide. Hydrogen peroxide was the oxidant. The maximum yield of tereplithalic acid, 49 +/- 8%, occurred at 300 degreesC with manganese bromide as the catalyst. Other catalysts or catalyst combinations produced lower yields. Yields of tereplithalic acid decreased as the oxidant-top-xylene ratio decreased, either by increasing the initial concentration of p-xylene or by decreasing the initial concentration of oxidant.