Study On Synthesis Of Tungsten Catalyst And Olefin Epoxidation And Oxidation Of Alcohols

Catalyst tungsten always exists in the forms of simple substance, tungsten oxidation and polyoxometalates. They are widely used in many reactions, such as epoxidation of olefin and oxidation of alcohol. In these reactions, molecular oxygen, hydrogen pexoxide and organic peroxides are normal oxidations. Using traditional catalyst tungsten requires strict reaction conditions and it needs lots of organic reagents as solvents, which may pollute the environment.A new ionic liquid peroxotungstate ([(CH3)N(C8H17)3]2W2O11) and four new peroxotungstates ([Mor1,n]NaW2O11(n=2,5,8,9)) were synthesized and characterized by infrared spectroscopy,’H-NMR and elemental analysis. The results showed that they were pure. And then, the new ionic liquid was used as catalyst to catalyze epoxidation of olefin and oxidation of alcohols. We used the single factor analysis method and the orthogonal experiment method to determine the best reaction conditions.We can see from the experiment results that when cyclooctene (1 mmol), acetonitrile (0.4 mL), catalyst (40μmol) and UHP (2.5 mmol) are used in this amount at 60℃, the epoxide yield is 99.3% and selectivity is over 99%. Among all the reaction conditions (catalyst, oxidant, solvent), the catalyst plays a key role in the epoxidation of cyclooctene. We can see from the experiment results that when cyclohexene (1 mmol), acetonitrile (0.3 mL), catalyst (30μmol), and UHP (3 mmol) are used in this amount at 60℃, the epoxide yield is 87.48%. Among all the reaction conditions (catalyst, oxidant, solvent), the oxidant plays a key role in the epoxidation of cyclohexene.The best reaction system of cyclohexanol oxidation is that the amount of cyclohexanol is 5 mmol, the amount of 30% H2O2 15 mmol, the amount of peroxotungstate 30 μmol and temperature 75℃. Among all the reaction conditions (catalyst, oxidant, solvent), the oxidant plays a key role in the oxidation of cyclohexanol.The catalyst can be recycled four times and the activity is almost unchanged. The best reaction system of benzyl alcohol oxidation is that the amount of benzyl alcohol is 5 mmol, the amount of 30% H2O2 20 mmol, the amount of peroxotungstate 100μmol and temperature 70℃, the yield of benzoic acid is over 99 %.In the reaction system of peroxotungstates ([Mor,n]NaW2O11(n=2,5,8,9)) as catalyst, we can see from the experiment results that when cyclooctene(1 mmol), acetonitrile (0.5 mL), catalyst (30 μmol) and 30% H2O2 (2 mmol) are used in this amount at 70℃, the epoxide yield and selectivity are best. We can see from the experiment results that when cyclohexene (1 mmol), acetonitrile (0.3 mL), catalyst (30 μmol), and UHP (2.5 mmol) are used in this amount at 65℃, the epoxide yield and selectivity are best. Among all the reaction conditions (catalyst, oxidant, solvent), the oxidant plays a key role in the epoxidation of cyclohexene.In short, the system has high catalytic activity for olefin epoxidation and cyclohexanol oxidation reaction with the peroxotungstate as catalyst. The system has a very good prospect in industrial application using 30% H2O2 as oxidation which is friendly to environment.