Cross metathesis approach to C11-C13 fatty-chain amino esters from oleic acid derivatives
A concise method of producing nylon 11, 12, or 13 precursors from oleic acid or an ester of oleic acid is described. The method involves cross-metathesis reactions as the key C—C bond formation step. Subsequent steps are provided to convert the metathesis product to the corresponding nylon precursors. Also provided are the products of the method.
1. A method of producing an amino acid or an amino ester, the method comprising:
subjecting oleic acid or an ester of oleic acid to a cross-metathesis reaction with a coupling substrate of formula X—(CH 2 ) n —CH=CHY, to produce an intermediate of formula X—(CH 2 ) n —CH=CH—(CH 2 ) 7 —COOR, wherein n=1 or 2, X=OH or CN, Y=H or CH 2 OH, and R is either hydrogen or an alkyl group;
subjecting the intermediate to one or more reactions to convert X into an amino group, to produce an amino acid or an amino ester; wherein the intermediate is subjected to a hydrogenation reaction to reduce unsaturated bonds in the intermediate and produce either (i) a reduced intermediate, or (ii) an amino acid or an amino ester; and,
converting a hydroxyl group of the reduced intermediate into an amine to produce an amino acid or an amino ester; wherein the step of converting a hydroxyl group into an amine comprises either sulfonate ester formation followed by displacement of the sulfonate ester with ammonia, or halogenation followed by displacement of the halide with ammonia.
2. The method of claim 1 , wherein the cross-metathesis reaction is conducted in the presence of a metathesis catalyst.
3. The method of claim 2 , wherein the metathesis catalysts comprises a tungsten-, molybdenum-, or ruthenium-based complex, or a Group 8 transition metal complex.
4. The method of claim 2 , wherein the metathesis catalyst comprises a second generation Hoveyda-Grubbs catalyst.
5. The method of claim 2 , wherein the metathesis catalyst is attached to a solid support.
6. The method of claim 2 , wherein the metathesis catalyst is present at a catalyst loading ranging from about 0.25 mol% to about 4 mol% of the coupling substrate.
7. The method of claim 2 , wherein the metathesis catalyst is dissolved in a metathesis solvent selected from the group consisting of chlorobenzene, toluene, dichloroethane, chloropentafluorobenzene, octafluorotoluene, ethyl acetate, isopropyl acetate, hexane, heptane, diethyl ether, and MTBE.
8. A method of producing an amino acid or an amino ester, the method comprising:
subjecting oleic acid or an ester of oleic acid to a cross-metathesis reaction with a coupling substrate of formula X—(CH2)n—CH=CHY, to produce an intermediate of formula X—(CH2)n—CH=CH—(CH2)7—COOR, wherein n=1 or 2, X=OH or CN, Y=H or CH2OH, and R is either hydrogen or an alkyl group; and
subjecting the intermediate to one or more reactions to convert X into an amino group, to produce an amino acid or an amino ester;
wherein the coupling substrate of formula X—(CH 2 ) n —CH=CHY is cis-butene-1,4-diol (HO—CH 2 —CH=CH—CH 2 —OH), and the resulting amino acid or amino ester is nylon 11 precursor.
9. The method of claim 8 , wherein the molar ratio of the cis-butenen-1,4-diol to the oleic acid or the ester of oleic acid is about five equivalents.
10. The method of claim 1 , wherein the coupling substrate of formula X—(CH 2 ) n —CH=CHY is allyl cyanide (NC—CH 2 —CH=CH 2 ), and the resulting amino acid or amino ester is nylon 12 precursor.
11. The method of claim 10 , wherein the molar ratio of the allyl cyanide to the oleic acid or the ester of oleic acid is about five equivalents.
12. The method of claim 1 , wherein the coupling substrate of formula X—(CH 2 ) n —CH=CHY is homoallyl cyanide (NC—(CH 2 ) 2 —CH=CH 2 ), and the resulting amion acid or amino ester is nylon 13 precursor.
13. The method of claim 12 , wherein the molar ratio of the homoallyl cyanide to the oleic acid or the ester of oleic acid is about 2.5 equivalents.
14. The method of claim 1 , wherein the cross-metathesis reaction is conducted in the presence of an additive selected from the group consisting of: 1,4-benzoquinone; 2,3-dichloro-1,4-benzoquinone; 2,3-difluoro-1,4-benzoquinone; and 2,3,5,6-tetrafluoro- 1,4-benzoquinone.
15. A method of producing an amino acid or an amino ester, the method comprising:
subjecting oleic acid or an ester of oleic acid to a cross-metathesis reaction with a coupling substrate of formula X—(CH2)n—CH=CHY, to produce an intermediate of formula X—(CH2)n-CH =CH—(CH2)7—COOR, wherein n=1 or 2, X=OH or CN, Y=H or CH2OH, and R is either hydrogen or an alkyl group; and
subjecting the intermediate to one or more reactions to convert X into an amino group, to produce an amino acid or an amino ester;
wherein the cross-metathesis reaction is conducted with cis-butene-1,4-diol, at a temperature ranging from about −10 ° C. to about 5 ° C.
16. The method of claim 1 , wherein the cross-metathesis reaction is conducted with allyl cyanide at a temperature ranging from about 95 ° C. to about 110 ° C.
17. The method of claim 1 , wherein the cross-metathesis reaction is conducted with homoallyl cyanide at a temperature ranging from about 95 ° C. to 110 ° C.
18. The method of claim 1 , wherein the cross-metathesis reaction is conducted at a concentration of the oleic acid or the ester of oleic acid ranging from about 0.025 mol/L to about 0.84 mol/L.
19. The method of claim 1 , wherein the cross-metathesis reaction lasts for a time period ranging from about 2 hours to about 21 hours.
20. The method of claim 1 , wherein the hydrogenation reaction is conducted in the presence of a hydrogenation catalyst selected from the group consisting of: palladium adsorbed on a support, with or without an additive; and a complex of rhodium iridium, rhenium, or ruthenium and carbene ligands.
21. The method of claim 20 , wherein the hydrogenation catalyst is present at a catalyst loading ranging from about 1 mol % to 6 mol % of the coupling substrate.
22. The method of claim 20 , wherein the hydrogenation catalyst comprises a potassium or sodium tert-butoxide additive at a loading of 15-30 mol % of the coupling substrate.
23. The method of claim 20 , wherein the hydrogenation reaction comprises dissolving the intermediate, sodium or potassium tert-butoxide, and the hydrogenation catalyst in a polar or non-polar hydrogenation solvent selected from the group consisting of chlorobenzene, toluene, dichloroethane, chloropentafluorobenzene, octafluorotoluene, ethyl acetate, isopropyl acetate, hexane, heptane, diethyl ether, MTBE, methanol, ethanol, and isopropanol.
24. The method of claim 1 , wherein the oleic acid or the ester of oleic acid is produced from algae-derived biomass.