Titanium Silicalite Ts-1 And The Ionic Liquid Aromatic Hydrocarbon Side-chain Oxidation

This dissertation consists of three parts: (1) catalytic oxidation of styrene using titanium silicalite zeolite (TS-1) to phenylacetaldehyde, (2) studies on catalytic oxidation of alkylarenes with titanium silicalite zeolite (TS-1), and (3) selective oxidation of alkylarenes in ionic liquids.1. Catalytic oxidation of styrene using titanium silicalite zeolite TS-1 to phenylacetaldehyde.In this part, we screened the reaction conditions under which styrene could be converted to phenylacetaldehyde in high yield with low substrate ratio: styrene/ H2O2=1.We found the optimum ratio for styrene, H2O2 and TS-1, and acetone was proved the most effective solvent for the reaction.There were some of high boiling point products isolated, which were presumably polymers. The addition of hydroquinone could suppress the side reaction and enhance the yield of phenylacetaldehyde.The catalyst TS-1 could be recycled after simply washing and calcining, and the yield of phenylacetaldehyde still reached 40% even after reusing it for 4 times.Under our optimum conditions the highest yield of phenylacetaldehyde was up to 60% which was significantly improved compared with 26% yield reported in literature. Thus, our results provided a procedure to obtain large quantities of the target compound avoiding high ratio of styrene to H2O2.Our procedure is economic, environmentally friendly and safe, due to its oxidant H2O2, its mild conditions and its catalyst which can be recycled. It may provide a practical method to prepare phenylacetaldehyde.2. Studies on catalytic oxidation of alkylarenes with titanium silicalite zeolite TS-1.In this part, we investigated the performance of TS-1 on oxidation of alkylarenesand screened the reaction conditions for high conversion of ethylbenzene.The oxidation of alkylarenes carried out over TS-1 produced mainly aromatic ketones, alcohols and small amount of hydroxybenzene. Although it was poor in 10 hours, the conversion of ethylbenzene can remarkably rise by increasing TS-1 or prolonging the reaction, for example more than 20% after 72 hours.Compared with that of styrene, the oxidation of ethylbenzene needed longer time to reach equilibrium and resulted in poorer conversion, but the activity of TS-1 kept active after several recycles, and the TS-1 could be recovered more easily.3. Selective oxidation of alkylarenes in ionic liquidsIn this part, the oxidation of styrene catalyzed by TS-1 and the oxidation of alkylarenes catalyzed by Co(OAc)2 in ionic liquids were investigated respectively.Ionic liquid [Emim]TBF4~, as a favorable solvent for oxidation, has been applied to oxidation of styrene catalyzed by TS-1 for the first time, and the satisfactory result was obtained: high conversion (50%) and high selectivity (90%), which is better than that reported in literature.Both [Bmim]+PF6- and [Bmim]+BF4-/HOAc (1:1) system were found to be suitable solvents for selective oxidation of alkylarenes catalyzed by Co(OAc)2 with molecular oxygen. Alkylarenes with a -methylene group could be oxidized to the corresponding aromatic ketones in mild conditions with high conversion and high selectivity in these ionic liquids, which could be reused. [Bmim]+BF4-/HOAc (1:1) system proved to be more stable than [Bmim]+PF6-.