Green Oxidation On Aromatic Side Chains And Coal-Related Model Compounds

The oxidation of aromatic side chains is of major reaction in organic synthesis, and improving its efficiency and selectivity for the high value-added products remains a challenge. Traditional approaches for the reaction were based on potassium hypermanganate oxdiation, but associated with the disadvantages of tedious work-up and pollution to the environment. In recent years, green oxidation of aromatic side chains is a continuous attracting issue as for the oxidation technology is concerned.With TBHP as the oxidant and G₁ as the catalyst, p-methylbenzene sulfonamide is oxidized to p-carboxybenzene sulfonamide. The amount of TBHP and G₁, the concentration of Na OH, reaction time and temperure are the five key factors of the oxidation were discussed. Under the optimized reaction conditions, the conversion of p-methylbenzene sulfonamide was as high as 93.02% and the yield of p-carboxybenzene sulfonamide was 88.86%. Finally, the mechanism was discussed. Then the oxidation of p-methylbenzene sulfonamide catalyzed by G₂/Co（OAc）₂ in acetic acid were investigated and the reaction took place to afford the corresponding p-carboxybenzene sulfonamide in good yields. The optimum reaction condition is as follows: p-methylbenzene sulfonamide（1 mmol）, catalyst G₂（5 mol%）, cocatalyst Co（OAc）₂（1 mol%）, 160 oC and oxygen（1 atm）. The highest yield of p-carboxybenzene sulfonamide was 94.95%. The mild condition, atmospheric pressure and moderate temperature, facilitated the green oxidation of the side chain of p-methylbenzene sulfonamide, an aromatic hydrocarbon with strong electron-withdrawing group.Then diphenylethane was chosen as the substrate to explore, the influence of six key factors such as the types of cocastysts, the sovents, the amount of G₂ and Co（OAc）₂, reaction time and temperure. Under the optimized reaction conditions, the conversion of diphenylethane was 99.98% and the yield of benzoic acid was 83.44%, The oxidation mechanism of diphenylethane under G₂/Co（OAc）₂/ O₂ was also discussed. Finally, Under the optimum reaction conditions, the diphenyl methane, 1-naphthol, 2-methyl naphthalene, triphenylmethane, fluorine, anthracene were oxidized, the oxidation products of model compounds were analyzed and their corresponding mechanism were discussed. The conversion rate of diphenyl methane was 95.72% and eight kinds of products were produced. The main products were benzoic acid, benzophenone and diphenylmethanol, whose content was 38.55%, 28.95% and 20.17% respectively; The conversion rate of triphenylmethane was 72.51% and four kinds of products were generated, the main products were benzophenone（31.53%） and triphenylmethanol（37.50%）; The conversion rate of 1-naphthol was 63.27% and five kinds of products were formed, the main product was 1,4-naphthoquinone（50.02%）; The conversion rate of 2-methyl naphthalene was 94.05% and eight kinds of products were come into being, the main products were 2-naphthaldehyde（20.29%）, naphthalene-2-cresol（28.44%） and 2-naphthalene acid（31.42%）; Anthracene only generated the anthraquinone and its content was 46.43%; The conversion rate of fluorene was 100% and six kinds of products were produced, the main product were 9H-fluoren-9-one（68.47%）, 9H-fluoren-9-ol（17.62%）.The third part is about G₂/Co（OAc）₂/O₂ catalytic oxidation system employed in the oxidation of macromolecular victory lignite. There are 123 compounds from victory lignite catalyzed by G₂/Co（OAc）₂/O₂, in which carboxylic acid compounds comprised the highest content. the results showed that the G₂/Co（OAc）₂/O₂ had a good effect not only on the oxidation of aromatic side chain, but also on that of aliphatic hydrocarbons. This method fulfiled the oxidation of macromolecular substances with no need for special equipments used under high temperature and high pressure.