Terry A. Isbell

Acid-Catalyzed Condensation of Oleic Acid into Estolides and Polyestolides

Oleic acid, when treated with 1.0 equivalent of perchloric acid at 50°C, produced a 76% yield of polyestolide. The concentration of mineral acid greatly affected the rate of estolide formation, with increased rates under high acid concentrations. Over a range of temperatures from room temperature to 100°C, reaction rates increased at higher temperatures. However, high acid concentrations and temperatures produced undesirable side products, primarily lactones. Other acids catalyze the condensation of oleic acid to form estolide with the following relative rates: HClO4 >H2SO4>p-toluenesulfonic>BF3·Et2O> montmorillonite K-10>HCl>H3PO4, HNO3. Addition of water impedes the formation of estolide.

Characterization of Estolides Produced from the Acid"Catalyzed Condensation of Oleic Acid

Estolides produced from an acid-catalyzed condensation of oleic acid were characterized by high-performance liquid chromatography (HPLC), gas chromatography (GC), GC-mass spectrometry (MS) and nuclear magnetic resonance (NMR). C-8 reverse-phase HPLC provided a clean resolution of the estolide oligomers present in the reaction mixtures, allowing an average oligomier distribution to be calculated. Corroboration of HPLC results were obtained either through hydrolysis of the estolide mixture and quantitation of the hydroxy fatty acid content by GC, through the integration of the α-methylene protons adjacent to the carbonyl of the acids vs. the esterns in the1H NMR spectrum, or by titration of the carboxylic acid with standardized base. GC and GC-MS analysis of the hydrolyzed estolide mixture indicated that the ester position were centered around the original double-bond position, with linkages ranging from positions 5–13. Likewise, the unsaturation was distributed along the fatty acid backbone.

Assessing phenotypic, biochemical, and molecular diversity in coriander (Coriandrum sativum L.) germplasm

Our goals for this research were to elucidate phenotypic and biochemical diversity in coriander (Coriandrum sativum L.) populations maintained at the North Central Regional Plant Introduction Station in Ames, IA, and examine relationships between amplified fragment length polymorphism (AFLP) markers and patterns of phenotypic and biochemical diversity. Phenotypic and biochemical traits were evaluated, and analyses of variance and mean comparisons were performed on the resulting data sets. Euclidean distances from phenotypic (PD) and biochemical (BD) data were estimated, and modified Rogers’ distances (RD) were estimated for 80 polymorphic AFLP markers. These data were subjected to cluster analyses (CA) and principal components analyses (PCA), to reveal patterns among populations, and to analyses of molecular variance (AMOVA) for grouping patterns from PD and BD by using the 80 polymorphic AFLP markers. Resulting phenotypic, biochemical, and molecular distance matrices were also compared by applying Mantel tests. Our results describe significant differences among populations for all the phenotypic traits, and dendrograms obtained from PD and BD revealed complex phenetic patterns, as did groups from PCA. The primary seed essential oils and nearly all fatty-acid components were identified and their abundance measured; the primary chemical constituents of corresponding PCA groups are described herein. Molecular evidence supported phenotypic and biochemical subgroups. However, variation attributed among subgroups and groups was very low (∼4–6%), while variation among populations within groups was intermediate (∼24–26%), and that within populations was large (∼69–70%), reflecting weak differentiation among subgroups and groups, which was confirmed by values for fixation indices. Phenotypic subgroups described in this study differed somewhat from previous infraspecific classifications. Weak correlations were found between the phenotypic and biochemical matrices and between the biochemical and AFLP matrices. No correlation was found between the phenotypic and AFLP matrices. These results may be related to coriander’s phenotypic plasticity, its wide range in lifecycle duration, its predominantly allogamous reproductive biology, a human-selection process focused on special traits that may be controlled by few genes, and the widespread trade of coriander seeds as a spice, which may result in dynamic, poorly differentiated molecular variation, even when phenotypic and biochemical differentiation is easily documented.

Characterization of monomers produced from thermal high-pressure conversion of meadowfoam and oleic acids into estolides

The monomers produced from thermal high-pressure conversion of meadowfoam or oleic acids into estolides were characterized as a complex mixture of fatty acids. Mild reaction conditions produced little change in the starting acids. However, vigorous reaction conditions,e.g. ≥3 h at 250°C with stirring, significantly altered the starting fatty acids.Cis/trans isomerization occurred readily, with the proportion oftrans isomers reaching 57%. In addition, the double bonds migrated throughout all positions of the hydrocarbon chain with concentrations diminishing outward from the starting double bond position. Branching was also observed to a small extent under these conditions and was even more pronounced in the absence of water. Lactones were also identified in the reaction mixture, with contents near 16% in the meadowfoam series. All products can be explainedvia carbocation rearrangement mechanisms that result from protonation of the starting olefins.

Methods for increasing estolide yields in a batch reactor

Estolides are formed when the carboxylic acid group of one fatty acid forms an ester link at the site of unsaturation of another fatty acid. These compounds have the potential to be used in a variety of applications, such as lubricants, greases, plastics, inks, cosmetics, and surfactants. By manipulating the reaction equilibrium, yields of 20% estolide in clay-catalyzed estolide reactions have been increased to 30%. Reactions conducted at 180°C, where water was vented out of the reactor at specific times, not only gave dimer-free estolides but also yields up to 30%. Steam has also been used instead of water with similar results. Estolides were quite stable at temperatures up to 250°C, even when they were exposed to air.

Examining Cuphea as a Potential Host for Western Corn Rootworm (Coleoptera: Chrysomelidae): Larval Development

Abstract In previous crop rotation research, adult emergence traps placed in plots planted to Cuphea PSR-23 (a selected cross of Cuphea viscosissma Jacq. and Cuphea lanceolata Ait.) caught high numbers of adult western corn rootworms, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), suggesting that larvae may have completed development on this broadleaf plant. Because of this observation, a series of greenhouse and field experiments were conducted to test the hypothesis that Cuphea could serve as a host for larval development. Greenhouse-grown plants infested with neonates of a colonized nondiapausing strain of the beetle showed no survival of larvae on Cuphea, although larvae did survive on the positive control (corn, Zea mays L.) and negative control [sorghum, Sorghum bicolor (L.) Moench] plants. Soil samples collected 20 June, 7 July, and 29 July 2005 from field plots planted to Cuphea did not contain rootworm larvae compared with means of 1.28, 0.22, and 0.00 rootworms kg−1 soil, respectively, for samples collected from plots planted to corn. Emergence traps captured a peak of eight beetles trap−1 day−1 from corn plots on 8 July compared with a peak of 0.5 beetle trap−1 day−1 on 4 August from Cuphea plots. Even though a few adult beetles were again captured in the emergence traps placed in the Cuphea plots, it is not thought to be the result of successful larval development on Cuphea roots. All the direct evidence reported here supports the conventional belief that rootworm larvae do not survive on broadleaf plants, including Cuphea.

Synthesis of Chloroalkoxy eicosanoic and docosanoic acids from meadowfoam fatty acids by oxidation with aqueous sodium hypochlorite

Chloroalkoxy substituted C20 and C22 fatty acids can be synthesized from the unsaturated fatty acids in meadow-foam oil by reaction of the fatty acids with primary or secondary alcohols and an aqueous sodium hypochlorite solution (commercial bleach). The reactions are conducted at room temperature for 3 h. Chlorohydroxy fatty acid derivatives are formed as by-products owing to the presence of water in the reaction mixture. Chlorinated δ-lactones are also produced by direct reaction of sodium hypochlorite with the Δ5 unsaturated fatty acids present in meadowfoam or by ring closure of the 6-chloro-5-hydroxy fatty acids. The product yield of chloroalkoxy fatty acids is dependent on the nature and volume of the alcohol used in the reaction, as well as the concentration and pH of the sodium hypochlorite solution. Primary alcohols such as methanol and butanol produce maximal yields (50–60%) of chloroalkoxy fatty acids whereas the secondary alcohol 2-propanol gives a 30% yield. Chloroalkoxy fatty acid yields can be increased to 75–80% by elimination of water from the reaction mixture through a procedure that partitions sodium hypochlorite from water into hexane/ethyl acetate mixtures. All of the reaction products were fully characterized using nuclear magnetic resonance and gas chromatography-mass spectrometry.

Estolides: Synthesis and Applications**Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.

Abstract Estolides are formed by the formation of a carbocation at the site of unsaturation that can undergo nucleophilic addition by another fatty acid, with or without carbocation migration along the length of the chain, to form an ester linkage. The secondary ester linkages of the estolide are more resistant to hydrolysis than those of triglycerides, and the unique structure of the estolide results in materials that have far superior physical properties for lubricant applications than traditional vegetable and mineral oils. These benefits, among others, have led formulators to begin using estolides in a variety of industrial and automotive lubricant applications. Combined efforts of the USDA and Biosynthetic Technologies LLC have led to the first estolide motor oil formulations (5W-20 and 5W-30) certified by the American Petroleum Institute (API), which meet the industry’s current motor oil standard. The different types of estolide types and synthesis are described as well as an in-depth look at the physical properties and how they relate to the estolide structures. The current commercial estolide will have some of its properties revealed as well as some information on a Las Vegas, Nevada field trial using estolide-based formulations. Many industry experts consider estolides to be the next generation of high-performance synthetic lubricants.

Estolides: Synthesis and Applications

Abstract Estolides are formed by the formation of a carbocation at the site of unsaturation that can undergo nucleophilic addition by another fatty acid, with or without carbocation migration along the length of the chain, to form an ester linkage. The secondary ester linkages of the estolide are more resistant to hydrolysis than those of triglycerides, and the unique structure of the estolide results in materials that have far superior physical properties for lubricant applications than traditional vegetable and mineral oils. These benefits, among others, have led formulators to begin using estolides in a variety of industrial and automotive lubricant applications. Combined efforts of the USDA and Biosynthetic Technologies LLC have led to the first estolide motor oil formulations (5W-20 and 5W-30) certified by the American Petroleum Institute (API), which meet the industry’s current motor oil standard. The different types of estolide types and synthesis are described as well as an in-depth look at the physical properties and how they relate to the estolide structures. The current commercial estolide will have some of its properties revealed as well as some information on a Las Vegas, Nevada field trial using estolide-based formulations. Many industry experts consider estolides to be the next generation of high-performance synthetic lubricants.

Chapter 14 – Estolides: Synthesis and Applications*

Abstract Estolides are formed by the formation of a carbocation at the site of unsaturation that can undergo nucleophilic addition by another fatty acid, with or without carbocation migration along the length of the chain, to form an ester linkage. The secondary ester linkages of the estolide are more resistant to hydrolysis than those of triglycerides, and the unique structure of the estolide results in materials that have far superior physical properties for lubricant applications than traditional vegetable and mineral oils. These benefits, among others, have led formulators to begin using estolides in a variety of industrial and automotive lubricant applications. Combined efforts of the USDA and Biosynthetic Technologies LLC have led to the first estolide motor oil formulations (5W-20 and 5W-30) certified by the American Petroleum Institute (API), which meet the industry’s current motor oil standard. The different types of estolide types and synthesis are described as well as an in-depth look at the physical properties and how they relate to the estolide structures. The current commercial estolide will have some of its properties revealed as well as some information on a Las Vegas, Nevada field trial using estolide-based formulations. Many industry experts consider estolides to be the next generation of high-performance synthetic lubricants.