Synthesis and physical properties of new coco-oleic estolide branched esters

- The coco-oleic dimer estolide and coco-oleic trimer plus estolide were esterified with a series of different alcohols.
- The coco-oleic dimer estolide 2-hexyldecanol esters had the lowest PP = −45 °C.
- The coco-oleic dimer estolide 2-octyldodecanol esters had PP = −39 °C.
- The coco-oleic trimer plus estolide esters had slightly higher PPs (−24 to −39 °C).
- The coco-oleic dimer estolide esters were of a lower viscosity range compared to the coco-oleic trimer plus estolide esters.

Oils derived from vegetable oils tend to not meet the standards for industrial lubricants because of unacceptable low temperature properties, pour point (PP) and/or cloud point (CP). However, a catalytic amount of perchloric acid with oleic and coconut (coco) fatty acids produced a coco-oleic estolide. The resulting coco-oleic estolide was separated into two components based on the extent of oligomerization: coco-oleic dimer estolide and coco-oleic trimer plus estolide. These two estolides were then esterified with a series of different branched alcohols; the coco-oleic dimer estolide esters had the lowest PP = −45 °C when with esterified 2-hexyldecanol and PP = −39 °C with 2-octyldodecanol. The best CP performer from the same series was the 2-octyldodecanol ester, CP = −37 °C. The coco-oleic trimer plus estolide esters had slightly higher PPs (−24 to −39 °C) with the same alcohols. The viscosities and viscosity indexes were as expected in terms of trends. The coco-oleic dimer estolide esters ranged 27.5-51.7 cSt @ 40 °C and 3.0-9.5 cSt @ 100 °C, whereas the coco-oleic trimer plus estolide esters ranged 120.8-227.7 cSt @ 40 °C and 17.9-29.4 cSt at 100 °C for the same series as the dimer esters. Outside the series tested, an iso-stearyl trimer plus ester had the highest reported viscosity of 417.3 cSt @ 40 °C and 38.9 cSt @ 100 °C. Because these new branched estolide esters have excellent viscosity and low temperature physical properties without the addition of other chemicals, they minimize the effect on the environment while replacing nonrenewable products.