Aerobic Oxidation Of P-xylene To Prepare P-toluic Acid And Terephthalic Acid Catalyzed By Metalloporphyrins

The liquid-phase catalytic oxidation of p-xylene by molecular oxygen is an important reaction for the production of commodity chemicals, such as p-toluic acid and terephthalic acid. p-Toluic acid is widely used in the synthesis of medicine, spices and fine chemicals, and terephthalic acid is an important precursor for manufacturing polymers commonly made into fibers, resins, films, etc. Environmental and energy crisis presses, in the field of p-xylene oxidation, are forcing industry to develop new catalytic routes to replace the traditional Co/Mn/Br catalytic system. Recently, extensive attention has been paid to metalloporhyrins, analogous complexes mimicing the behavior of cytochrome P-450 that can use dioxygen to functionalize hydrocarbons under ambient condtions.To investigate the selective aerobic oxidation of p-xylene to produce aromatic acids, the simple metalloporphyrins are introduced to catalyze p-xylene under various conditions in the absence of any co-catalysts or additives.The contents of this thesis are presented as follows:1. The liquid-phase oxidation of p-xylene is conducted in an autoclave, and the oxidation products are conformed by GC-MS and LC using standard compound as contrast.2. A new and effective way of analysis of oxidation products of p-xylene using high performance liquid chromatography is proposed.3. Five kinds of metalloporphyrins are synthesized to investigate their catalysis on the aerobic oxidation of p-xylene to produced terephthalic acid and p-toluic acid. Results show that manganese tetraphenylporphyrin(TPPMnCl) is the most effective catalyst under optimum condition and give 34% conversion of p-xylene and 92% selectivity of p-toulic acid and 6% selectivity of terephthalic acid.4. TPPMnCl is employed to investigate the effect of different reaction condition, such as solvent, reaction time, temperature, pressure, the stucture and concentration of catalysts, air flow and water containing in the system on the oxidation reaction.5. According the present research and the phenomenon appearing in our experiments, the possible mechanism of p-xylene oxidaton catalyzed by metalloporphyrins is suggested.6. A new method of preparing p-toluic acid is brought forward.