Methods of making organic compounds by metathesis
Described are methods of making organic compounds by metathesis chemistry. The methods of the invention are particularly useful for making industrially-important organic compounds beginning with starting compositions derived from renewable feedstocks, such as natural oils. The methods make use of a cross-metathesis step with an olefin compound to produce functionalized alkene intermediates having a pre-determined double bond position. Once isolated, the functionalized alkene intermediate can be self-metathesized or cross-metathesized (e.g., with a second functionalized alkene) to produce the desired organic compound or a precursor thereto. The method may be used to make bifunctional organic compounds, such as diacids, diesters, dicarboxylate salts, acid/esters, acid/amines, acid/alcohols, acid/aldehydes, acid/ketones, acid/halides, acid/nitriles, ester/amines, ester/alcohols, ester/aldehydes, ester/ketones, ester/halides, ester/nitriles, and the like.
1. A method comprising:
providing (a) a starting material comprising unsaturated fatty acid triglycerides and (b) short-chain alpha-olefins;
cross-metathesizing the unsaturated fatty acid triglycerides of the starting material and the short-chain alpha-olefins in the presence of a metathesis catalyst to provide cross-metathesis products comprising olefins and ester-functionalized alkenes, wherein the ester-functionalized alkenes comprise unsaturated fatty acid triglycerides;
separating the olefins in the cross-metathesis products and the ester-functionalized alkenes in the cross-metathesis products to provide separated olefins and separated ester-functionalized alkenes, wherein the separated ester-functionalized alkenes comprise unsaturated fatty acid triglycerides; and
transesterifying the separated ester-functionalized alkenes in the presence of an alcohol to provide a transesterified product comprising glycerol and free ester-functionalized alkenes.
2. The method of claim 1 , further comprising:
separating spent metathesis catalyst in the cross-metathesis products to provide separated spent metathesis catalyst.
3. The method of claim 1 , further comprising:
separating the glycerol in the transesterified product and the free ester-functionalized alkenes in the transesterified product to provide separated glycerol and separated free ester-functionalized alkenes.
4. The method of claim 3 , further comprising:
self-metathesizing the separated free-ester functionalized alkenes in the presence of second metathesis catalyst to provide a self-metathesis product comprising diester alkenes.
5. The method of claim 4 , further comprising:
hydrogenating the diester alkenes in the self-metathesis product.
6. The method of claim 1 , wherein the starting material is a natural oil.
7. The method of claim 6 , wherein the natural oil is a plant-based oil or animal fat.
8. The method of claim 7 , wherein the plaint-based oil is selected from the group consisting of: canola oil, rapeseed oil, coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, safflower oil, sesame oil, soybean oil, sunflower oil, linseed oil, palm kernel oil, tung oil, castor oil, and mixtures thereof.
9. The method of claim 7 , wherein the animal fat is selected from the group consisting of: lard, tallow, chicken fat, fish oil, and mixtures thereof.
10. The method of claim 1 , wherein the alcohol is a monohydric alcohol.
11. The method of claim 10 , wherein the monohydric alcohol is selected from the group consisting of: methanol, ethanol, propanol, butanol, and mixtures thereof.
12. The method of claim 10 , wherein the monohydric alcohol is methanol.
13. The method of claim 1 , wherein the short-chain alpha-olefins are selected from the group consisting of: 1-propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and mixtures thereof.