Methods of producing epoxides from alkenes using a two-component catalyst system
Methods for the epoxidation of alkenes are provided. The methods include the steps of exposing the alkene to a two-component catalyst system in an aqueous solution in the presence of carbon monoxide and molecular oxygen under conditions in which the alkene is epoxidized. The two-component catalyst system comprises a first catalyst that generates peroxides or peroxy intermediates during oxidation of CO with molecular oxygen and a second catalyst that catalyzes the epoxidation of the alkene using the peroxides or peroxy intermediates. A catalyst system composed of particles of suspended gold and titanium silicalite is one example of a suitable two-component catalyst system.
1. A method for the epoxidation of an alkene, the method comprising exposing the alkene to a two-component catalyst system in an aqueous solution, in the presence of carbon monoxide and molecular oxygen, under conditions in which the alkene is epoxidized, wherein the two-component catalyst system comprises a first catalyst that generates peroxides or peroxy intermediates during oxidation of CO with molecular oxygen and a second catalyst catalyzes the epoxidation of the alkene using the peroxides or peroxy intermediates.
2. The method of claim 1 , wherein the first catalyst comprises gold and the second catalyst comprise titanium silicalite.
3. The method of claim 1 , wherein the alkene has an allylic hydrogen.
4. The method of claim 3 , wherein the alkene is butene.
5. The method of claim 3 , wherein the alkene is propene.
6. The method of claim 1 , wherein the aqueous solution comprises an alcohol.
7. The method of claim 6 , wherein the alcohol is methanol.
8. The method of claim 7 , wherein the alkene has an allylic hydrogen.
9. The method of claim 6 , wherein the ratio of alcohol to water in the aqueous solution is at least 4:1 by volume.
10. The method of claim 6 having a selectivity for epoxide production of at least 90%.
11. The method of claim 10 having a selectivity for epoxide production of at least 99%.
12. The method of claim 1 , wherein the epoxidation of the alkene is carried out at a temperature of no greater than 50° C.
13. The method of claim 1 carried out in the absence of H 2 gas.
14. The method of claim 1 carried out in the absence of peroxy initiators.
15. The method of claim 1 carried out in the absence of H 2 or peroxy initiators, wherein the first catalyst comprises gold and the second catalyst comprises titanium silicalite, the alkene has an allylic hydrogen, and the aqueous solution comprises methanol.