Nonpolar phase-soluble metathesis catalysts
One embodiment of the invention provides polyisobutylene (PIB) oligomers that are end-functionalized with ruthenium (Ru) catalysts. Such nonpolar catalysts can be dissolved in nonpolar solvents such as heptane, or any other nonpolar solvent that is otherwise not latently biphasic (i.e., if two or more solvent components are present, they remain miscible with each other throughout the entire reaction process, from the addition of substrate through to the removal of product). Substrate that is dissolved in the nonpolar solvent with the catalyst is converted into product. The lower solubility of the product in the nonpolar solvent renders it easily removable, either by extraction with a more polar solvent or by applying physical means in cases where the product precipitates from the nonpolar solvent. In this manner the catalysts are recycled; since the catalysts remain in the nonpolar solvent, a new reaction can be initiated simply by dissolving fresh substrate into the nonpolar solvent.
1. A method of catalyzing a chemical reaction, the method comprising:
a) providing a reaction composition, wherein the reaction composition comprises:
i) a non-polar solvent, wherein the solvent is not latently biphasic,
ii) a catalyst that is complexed to a non-polar support, wherein the catalyst-support complex is dissolved in the solvent, and
iii) a substrate molecule dissolved in the solvent, wherein the substrate molecule is a substrate for the catalyst;
b) allowing the substrate molecule to be catalyzed into a product, wherein the product is less soluble in the solvent compared to the substrate molecule; and
c) separating the product from the reaction composition.
2. The method of claim 1 , wherein the solvent is selected from the group consisting of alkanes, heptane, toluene, dichloromethane, dibutyl ether, and combinations thereof.
3. The method of claim 1 , wherein the solvent comprises heptane.
4. The method of claim 1 , wherein the non-polar support is selected from the group consisting of polyisobutylene, polyethylene, poly(N-octadecylacrylamide), polysiloxane, polyamidoamine, poly(1-alkene), polypropylene, and combinations thereof.
5. The method of claim 1 , wherein the non-polar support comprises polyisobutylene.
6. The method of claim 1 , wherein the catalyst comprises a metal selected from the group consisting of ruthenium, silver, and combinations thereof.
7. The method of claim 1 , wherein the catalyst comprises functional groups selected from the group consisting of an imidazole group, a thiazole group, a pyridine group, trioorganophosphine, nucleophilic organic groups, hydrocarbons, hydrocarbons containing one or more ester groups, hydrocarbons containing one or more ether groups, hydrocarbons containing one or more amine groups, and combinations thereof.
8. The method of claim 1 , wherein the catalyst-support complex remains dissolved in the non-polar solvent throughout the entire process.
9. The method of claim 1 , wherein the catalyst-support complex comprises an N-heterocyclic carbene moiety.
10. The method of claim 1 , wherein the separating occurs by physical means, and wherein the product is insoluble in the non-polar solvent.
11. The method of claim 10 , wherein the physical means comprise siphoning, filtering, or decanting.
12. The method of claim 1 , wherein the separating occurs by extracting the product.
13. The method of claim 12 , wherein the extracting occurs by adding and removing a second solvent to the reaction composition, wherein the product is preferably soluble in the second solvent compared to the non-polar solvent.
14. The method of claim 13 , wherein the second solvent is a polar organic solvent.
15. The method of claim 13 , wherein the second solvent comprises acetonitrile.
16. The method of claim 1 , further comprising:
d) reusing the catalyst-support complex by dissolving fresh substrate into the non-polar solvent.
17. The method of claim 1 , wherein the substrate molecule is a substrate for a ring-closing, ring-opening or cross metathesis polymerization reaction.
18. The method of claim 1 , wherein the product is completely insoluble in the solvent.