High- and low-viscosity estolide base oils and lubricants
Provided herein are compounds of the formula: in which n is an integer equal to or greater than 1; R 2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and R 1 , R 3 , and R 4 , independently for each occurrence, are selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched, wherein compositions comprising the compounds are characterized by particular combinations of values for estolide number, kinematic viscosity, and pour point. Also provided are compositions containing the compounds and methods of making both the compounds and compositions thereof.
1. A method of retaining or decreasing the pour point of an estolide base oil by increasing the EN of the estolide base oil, said method comprising:
selecting an estolide base oil having an initial EN and an initial pour point; and
removing at least a portion of the estolide base oil, said portion exhibiting an EN that is less than the initial EN of the estolide base oil,
wherein the resulting estolide base oil exhibits an EN that is greater than the initial EN of the estolide base oil, and a pour point that is equal to or lower than the initial pour point of the estolide base oil, and wherein EN is the average number of estolide linkages for estolide compounds comprising the estolide base oil.
2. The method according to claim 1 , wherein removing at least a portion of the estolide base oil is accomplished by at least one of distillation, chromatography, membrane separation, phase separation, or affinity separatione.
3. The method according to claim 2 , wherein removing at least a portion of the estolide base oil is accomplished by distillation.
4. The method according to claim 1 , wherein the estolide base oil has an initial EN of equal to or less than 2.5 and an initial pour point of equal to or greater than −40° C.
5. The method according to claim 1 , wherein the estolide base oil comprises at least one compound of Formula III:
wherein
x is, independently for each occurrence, an integer selected from 0 to 20;
y is, independently for each occurrence, an integer selected from 0 to 20;
n is an integer greater than or equal to 0;
R 1 is selected from optionally substituted alkyl and optionally substituted alkenyl, which are branched or unbranched; and
R 2 is selected from optionally substituted alkyl and optionally substituted alkenyl, which are branched or unbranched,
wherein each fatty acid chain residue of said at least one compound is independently optionally substituted.
6. The method according to claim 5 , wherein R 2 is selected from branched or unbranched C 1 to C 20 alkyl and branched or unbranched C 1 to C 20 alkenyl.
7. The composition according to claim 6 , wherein R 2 is selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decanyl, undecanyl, dodecanyl, tridecanyl, tetradecanyl, pentadecanyl, hexadecanyl, heptadecanyl, octadecanyl, nonadecanyl, and icosanyl, which are saturated and branched or unbranched.
8. The method according to claim 5 , wherein R 2 is selected from branched or unbranched C 6 to C 12 alkyl that is unsubstituted.
9. The method according to claim 8 , wherein R 2 is 2-ethylhexyl.
10. The method according to claim 5 , wherein R 1 is selected from unsubstituted C 7 to C 17 alkyl that is unbranched, and unsubstituted C 7 to C 17 alkenyl that is unbranched.
11. The method according to claim 10 , wherein R 1 is selected from C 7 alkyl, C 9 alkyl, C 11 alkyl, C 13 alkyl, C 15 alkyl, C 17 alkyl, and C 17 alkenyl, which are unsubstituted and unbranched.
12. The method according to claim 5 , wherein R 1 is selected from C 13 to C 17 alkyl and C 13 to C 17 alkenyl, which are unsubstituted and unbranched.
13. The method according to claim 12 , wherein R 1 is selected from C 13 alkyl, C 15 alkyl, C 17 alkyl, and C 17 alkenyl, which are unsubstituted and unbranched.
14. The method according to claim 1 , wherein the portion of the estolide base oil exhibits an EN that is less than 2.5.
15. The method according to claim 14 , wherein the portion of the estolide base oil exhibits an EN that is less than 2.0.
16. The method according to claim 15 , wherein the portion of the estolide base oil exhibits an EN that is less than 1.5.
17. The method according to claim 14 , wherein the EN of the resulting estolide base oil is greater than 2.5.
18. The method according to claim 17 , wherein the EN of the resulting estolide base oil is greater than 3.0.
19. The method according to claim 18 , wherein the EN of the resulting estolide base oil is greater than 4.0.
20. The method according to claim 4 , wherein the pour point of the resulting estolide base oil is equal to or less than −40° C.
21. The method according to claim 4 , wherein the estolide base oil has an initial EN of equal to or less than 2.0 and an initial pour point of equal to or greater than −35° C.
22. The method according to claim 4 , wherein the portion of the estolide base oil exhibits an EN that is less than 2.0.
23. The method according to claim 4 , wherein the portion of the estolide base oil exhibits an EN that is less than 1.5.
24. The method according to claim 22 , wherein the EN of the resulting estolide base oil is greater than 2.5.
25. The method according to claim 22 , wherein the EN of the resulting estolide base oil is greater than 3.0.
26. The method according to claim 5 , wherein said estolide base oil comprises two or more compounds of Formula III.
27. The method according to claim 5 , wherein said estolide base oil consists essentially of two or more compounds of Formula III.
28. The method according to claim 3 , wherein the distillation takes place at a temperature of at least 250° C. and a pressure of no greater than 25 microns absolute.