Processes of preparing estolide compounds that include removing sulfonate residues
Provided herein are processes of preparing sulfonated estolide compounds, and the removal of sulfonate residues from those compounds to provide desulfonated estolide base oils. Exemplary sulfonated estolide compounds include those selected from the formula: wherein z is an integer selected from 0 to 15; q is an integer selected from 0 to 15; x is, independently for each occurrence, an integer selected from 0 to 20; y is, independently for each occurrence, an integer selected 0 to 20; n is equal to or greater than 0; R 6 is selected from —OH, optionally substituted alkyl, and optionally substituted aryl; and R 2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched, wherein each fatty acid chain residue of said compounds is independently optionally substituted.
1. A process of producing an estolide base oil comprising providing at least one first estolide compound having at least one sulfonate residue; and
eliminating the at least one sulfonate residue by exposing the at least one first estolide compound to heat and/or basic conditions to provide at least one desulfonated estolide compound that is unsaturated at the site of elimination.
2. The process according to claim 1 , wherein the at least one first estolide compound is prepared by a process that includes oligomerizing at least one first fatty acid reactant having at least one site of unsaturation with at least one second fatty acid reactant in the presence of a sulfonic acid catalyst.
3. The process according to claim 2 , wherein the at least one first fatty acid reactant is selected from one or more of an unsaturated fatty acid, an unsaturated fatty acid ester, or an unsaturated fatty acid oligomer.
4. The process according to claim 2 , wherein the at least one second fatty acid reactant is selected from one or more of a saturated fatty acid or an unsaturated fatty acid.
5. The process according to claim 2 , wherein the sulfonic acid catalyst is an unsubstituted alkyl sulfonic acid.
6. The process according to claim 2 , wherein at least a portion of the oligomerizing occurs at a temperature of 100° C. or less.
7. The process according to claim 6 , wherein at least a portion of the oligomerizing occurs at a temperature 70° C. or less.
8. The process according to claim 6 , wherein at least a portion of the oligomerizing occurs within a temperature range of 25° C. to 75° C.
9. The process according to claim 8 , wherein at least a portion of the oligomerizing occurs within a temperature range of 15° C. to 60° C.
10. The process according to claim 8 , wherein at least a portion of the oligomerizing occurs at a pressure of 1 atm or more.
11. The process according to claim 1 , wherein eliminating said at least one sulfonate residue includes contacting the at least one first estolide compound with a base.
12. The process according to claim 11 , wherein the base comprises at least one metal hydroxide.
13. The process according to claim 12 , wherein the base is selected from sodium hydroxide and potassium hydroxide.
14. The process according to claim 1 , wherein eliminating said at least one sulfonate residue includes heating the at least one first estolide compound to a temperature of at least 100° C.
15. The process according to claim 1 , wherein eliminating said at least one sulfonate residue includes heating the at least one first estolide compound to a temperature of at least 140° C.
16. The process according to claim 14 , wherein eliminating said at least one sulfonate residue includes heating the at least one first estolide compound under reduced pressure that is less than 1 atm abs.
17. The process according to claim 16 , wherein the reduced pressure is 25 torr abs or less.
18. The process according to claim 1 , further comprising esterifying the at least one desulfonated estolide compound with at least one alcohol to provide at least one esterified estolide compound.
19. The process according to claim 18 , further comprising hydrogenating the at least one esterified estolide compound to provide at least one saturated estolide compound.
20. The process according to claim 1 , wherein the at least one first estolide compound is selected from compounds of Formula III:
wherein
R 6 is selected from —OH, optionally substituted alkyl, and optionally substituted aryl;
z is an integer selected from 0 to 12;
q is an integer selected from 0 to 10;
x is, independently for each occurrence, an integer selected from 0 to 10;
y is, independently for each occurrence, an integer selected from 0 to 10;
n is an integer selected from 0 to 20; and
R 2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched,
wherein each fatty acid chain residue is unsubstituted.
21. The process according to claim 20 , wherein z is an integer selected from 7 and 8.
22. The process according to claim 20 , wherein q is an integer selected from 7 and 8.
23. The process according to claim 20 , wherein n is an integer selected from 0 to 12.
24. The process according to claim 20 , wherein n is an integer selected from 1 to 20.
25. The process according to claim 20 , wherein x+y is, independently for each fatty acid chain residue, an integer selected from 13 to 15.
26. The process according to claim 20 , wherein R 6 is —OH.
27. The process according to claim 11 , wherein the base is a carboxylate salt.
28. The process according to claim 11 , wherein the base is a nitrogenous base.
29. The process according to claim 28 , wherein the base is selected from one or more of a tertiary amine or an aromatic amine.
30. The process according to claim 20 , wherein R 6 is an optionally substituted alkyl.
31. The process according to claim 30 , wherein R 6 is unsubstituted.
32. The process according to claim 20 , wherein R 6 is an optionally substituted aryl.
33. The process according to claim 2 , wherein the sulfonic acid catalyst is an optionally substituted aryl sulfonic acid.
34. The process according to claim 2 , wherein the sulfonic acid catalyst is sulfuric acid.