| The catalytic oxidation of hydrocarbons is an extremely important industryoxidation reaction, and it is abroad applied in petroleum, medication industry and soon. In these oxidation reactions, the oxidation of toluene is an extremely importantreaction in chemical industry. The major products, benzaldehyde, benzyl alcohol andbenzoic acid are widely applied in spices, food, pesticides, medicine and otherchemical industries. At present, the toluene oxidation steps of industrial productionhave many shortcomings, such as, a large amount of catalyst, a complex process,discharging vast pollutants. Therefore, the studies on liquid phase oxidation toproduce benzaldehyde, benzyl alcohol and benzoic acid using more green reactionconditions are of great significance.Based on the results gained by formers in our lab, we reported a new method ofhomogeneous oxidation of toluene with dioxygen catalyzed by themetalloporphyrins/NHPI/CTAB (quaternary ammonium salt: Hexadecyl trimethylammonium bromide) system. It is a new catalytic system on liquid phase greencatalytic oxidation of toluene.In this paper, we firstly summarized the recent advances on industrialized statusquo of toluene oxidation, the recent advances on the main methods and bionicscatalysis system for toluene oxidation, the application of quaternary ammonium saltsin oxidation reactions, and explained the significance of toluene oxidation, as well asthe source of topics, significance and main contents.Secondly, a GC internal quantitatively analytical method was built, which wasoptimized and tested. It has the advantages of high sensitivity, brilliant selectivity,good accuracy, simplicity and rapidity.Thirdly, a new method of homogeneous green catalytic oxidation of toluene withdioxygen catalyzed by the metalloporphyrins/NHPI/CTAB system was studied. It wasfound in experiment that the quaternary ammonium salts (CTAB) had a greatinfluence on the reaction. The effects of reaction conditions, such as temperature, theflow of oxygen, the amount of catalyst, the concentration of toluene and differentmetalloporphyrins were investigated.Fourthly, the possible effective pathway for the quaternary ammonium salts(CTAB) to promote the oxidation were analyzed and demonstrated through the reaction intermediates of toluene oxidation. The influence of CTAB in the reactionintermediates of toluene oxidation was studied. On the basis of these and the wellstudied mechanism about metalloporphyrins and NHPI, we proposed a mechanism ofcatalytic cycle in the aerobic oxidation of toluene with dioxygen catalyzed by themetalloporphyrins/NHPI/CTAB system. |
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