No abstract

Camelina (Camelina sativa L.), a member of the Brassicaceae family, can potentially serve as a low‐input alternative oil source for advanced biofuels as well as food and other industrial uses. Winter annual camelina genotypes may be economically and environmentally advantageous for the northern Corn Belt, but little is known about their agronomic potential for this region. A 2‐yr field study was conducted in western Minnesota to determine optimum fall sowing time for yield and oil content of two winter camelina cultivars in a no‐tillage (NT) and chisel‐plowed (CP) system. Seeding dates ranged from early September to mid‐October. Plants reached 50% flowering as much as 7 d earlier in the NT than the CP system. Plant stands were generally greatest in the NT system, but yields were only greater than those in the CP system during the second year of the study, possibly due to differences in water logging of soil between tillage systems. Seed yield and oil content increased with sowing date up to early October. When sown in October, seed yield and oil content ranged from 419 to 1317 kg ha−1 and 282 to 420 g kg−1, respectively. Results indicate that camelina is a viable winter crop for the northern Corn Belt and that seed yields and oil content tended to be greatest when sown in early to mid‐October. Moreover, fall‐seeded camelina offered good weed suppression without the use of herbicide, supporting the contention that it can be successfully produced with low agricultural inputs.

Oleic acid and various saturated fatty acids, butyric through stearic, were treated with 0.4 equivalents of perchloric acid at either 45 or 55°C to produce complex estolides. Yields varied between 45 and 65% after Kugelrohr distillation. The estolide number (EN), i.e., the average number of fatty acid units added to a base fatty acid, varied as a function of temperature and saturated fatty acid. The shorter-chain saturated fatty acids, i.e., butyric and hexanoic, provided material with higher degrees of oligomerization (EN = 3.31) than stearic acid (EN = 1.36). The individual, saturated fatty acid estolides each have very different characteristics, such as color and type of by-products. The higher-temperature reactions occurred at faster rates at the expense of yield, and lactones were the predominant side products. At 55°C, lactone yields increased, but the δ-γ-lactone ratio decreased; this led to lower estolide yields. The opposite trend was observed for the 45°C reaction. The saturate-capped, oleic estolides were then esterified with 2-ethylhexyl alcohol, and the chemical composition of these new estolides remained consistent throughout the course of the reaction.Paper no. J9799 in JAOCS 78, 557-565 (June 2001).Estolides are a class of esters, based on vegetable oils (1-4), that form when the carboxylic acid functionality of one fatty acid reacts at the site of unsaturation of another fatty acid to form an ester linkage. These linkages are used to help characterize the structure of the estolide since the estolide number (EN) is defined as the average number of fatty acids added to a base fatty acid (Scheme 1, EN = n + 1). 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 certain applications than vegetable and mineral oils (5). Estolides have been found in nature (6,7) and have been synthesized (1-4,8) in the laboratory. Isbell and Kleiman (9) synthesized estolides from oleic fatty acids and found them to have interesting chemical behavior. The double bond in oleic acid is located at the 9 position which, under the correct conditions of acid concentration, reaction time, and temperature, undergoes estolide formation with minimal migration. The proposed mechanism involves formation of a carbocation that can undergo nucleophilic addition with or without carbocation migration along the length of the chain. If the migration continues to the C4 and C5 position, the fatty acid will cyclize to form lactones, the major side product to estolide formation (Scheme 2) (10-15).Lactones are formed from an intramolecular cyclization of a fatty acid carboxyl group with a carbocation located at the 4-or 5-position on a fatty acid backbone. Under the correct conditions, Showell et al. (13) and Cermak and Isbell (14,15) were able to produce γ-and δ-lactones, respectively. A major side product in the estolide synthesis, lactones are an interesting class of compounds...

Hematophagous arthropods are capable of transmitting human and animal pathogens worldwide. Vector-borne diseases account for 17% of all infectious diseases resulting in 700,000 human deaths annually. Repellents are a primary tool for reducing the impact of biting arthropods on humans and animals. N,N-Diethyl-meta-toluamide (DEET), the most effective and long-lasting repellent currently available commercially, has long been considered the gold standard in insect repellents, but with reported human health issues, particularly for infants and pregnant women. In the present study, we report fatty acids derived from coconut oil which are novel, inexpensive and highly efficacious repellant compounds. These coconut fatty acids are active against a broad array of blood-sucking arthropods including biting flies, ticks, bed bugs and mosquitoes. The medium-chain length fatty acids from C8:0 to C12:0 were found to exhibit the predominant repellent activity. In laboratory bioassays, these fatty acids repelled biting flies and bed bugs for two weeks after application, and ticks for one week. Repellency was stronger and with longer residual activity than that of DEET. In addition, repellency was also found against mosquitoes. An aqueous starch-based formulation containing natural coconut fatty acids was also prepared and shown to protect pastured cattle from biting flies up to 96-hours in the hot summer, which, to our knowledge, is the longest protection provided by a natural repellent product studied to date.