A brief review of para-xylene oxidation to terephthalic acid as a model of primary C-H bond activation

The oxidation of para-xylene to terephthalic acid has been commercialised as the AMOCO process (Co/Mn/Br) that uses a homogeneous catalyst of cobalt and manganese together with a corrosive bromide compound as a promoter. This process is conducted in acidic medium at a high temperature (175-225 degrees C). Concerns over environmental and safety issues have driven studies to find milder oxidation reactions of para-xylene. This review discussed past and current progress in the oxidation of para-xylene process. The discussion concentrates on the approach of green chemistry including (1) using heterogeneous catalysts with promising high selectivity and mild reaction condition, (2) application of carbon dioxide as a co-oxidant, and (3) application of alternative promoters. The optimisation of para-xylene oxidation was also outlined. (C) 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.