Steven C. Cermak

The indeterminate flowering nature of industrial hemp results in harvested seeds with varying maturity. This study employed density grading to separate seeds into fractions with different test weights, which were characterized for physical properties, chemical composition, and oil quality. Grading shifted 73.2% of seeds to heavier fractions with significantly greater thousand‐seed weight (14.6–17.8 g), bulk density (530–581 g/L), and true density (1129.5–1149.0 g/L) compared to lighter fractions (7.1–12.6 g; 334–500 g/L; 1089.2–1223.7 g/L, respectively). Heavier seeds were darker (L* 48.17–49.16 vs. 50.07–53.16) and contained more oil (29.2%–31.0% vs. 14.1%–23.3%). Protein (21.2%–25.3%) and ash (4.1%–4.6%) varied minimally, while crude fiber was highest in the lightest fraction (43.3%). Cold pressing recovered 56.7%–69.4% of oil; hexane extraction of the press cake achieved 99.8% overall recovery. Cold‐pressed oils were lighter (chlorophyll 14–37 ppm) than hexane‐extracted oils (75–85 ppm). Linoleic (52.6%–53.5%), α‐linolenic (16.2%–17.2%), and oleic acids (12.4%–13.6%) were predominant fatty acids. Palmitic acid was the major saturated fatty acid (8.2%–10.8%). Oils from heavier seeds contained more monounsaturated fatty acids, while polyunsaturated levels were similar across fractions. Protein solubility was higher in heavier seeds, dominated by glutelins (57.5%–65.7%), followed by globulins (9.1%–13.6%) and prolamins (8.0%–9.4%). Extended storage at 23°C and high polyunsaturated content caused severe oxidation, rendering oils unsuitable for food but suitable for biofuel, lubricants, or refining into fatty acids, mono‐ and diglycerides, and glycerol.

Hempseed oil (HSO) bears the unique property of its fatty acid profiles being unusually rich with polyunsaturated fatty acids. While the presence of numerous olefins would make this oil prone to oxidation, the presence of this functional group can be exploited to form oligomers called estolides, improving their oxidative stability and cold flow properties. In this work, a series of estolides were synthesized from HSO and high‐oleic HSO (HOHSO) which are capped with fatty acids of varying chain length and esterified with 2‐ethylhexanol (2‐EH). The estolides capped with shorter chain saturated fatty acids (C8–C14) exhibited excellent cold flow properties, with pour points of −36°C and lower. Estolides prepared from HSO had higher kinematic viscosities than those prepared from HOHSO. HOHSO estolides bore physical properties similar to estolides synthesized from oleic‐rich oils, which is advantageous for applications as bio‐based motor oils. Furthermore, the HSO/2‐EH estolide capped with a shorter chain fatty acid of the series synthesized (specifically caprylic/octanoic acid, C8:0) bore an unusually high kinematic viscosity compared to the rest of the series capped with longer chain fatty acids.

The transesterification of ethyl ferulate (EF) and unrefined, virgin, cold pressed hemp seed oil (HO_V) and refined, bleached, deodorized cold pressed hemp seed oil (HO_R) using a commercial lipase, Novozym 435 (Candida antarctica B lipase immobilized on an acrylic resin), was examined in 150‐mL, shaken, batch reactions at 60°C for 2 weeks. The reactions produced feruloylated hemp seed oils, FHO_V and FHO_R, respectively, and the reactions were monitored to determine the difference between virgin and refined hemp seed oil on the transesterifications. The FHO_V and FHO_R reactions both reached EF conversion equilibrium of 58% after ca. 168 h. Ultraviolet (UV) absorbing and antioxidant capacity of the FHO_V and FHO_R were determined. Both FHO_V and FHO_R (50 μM in ethanol) were excellent UVA II absorbers, λ_max 322 nm, and exhibited absorption into the UVB. The DDPH* radical (200 μM) scavenging of the FHO_V and FHO_R (0.25–2.5 mM) were both shown to be rapid antioxidants (50% DDPH* radical scavenged in V did not adversely affect enzyme activity relative to transesterification using HO_R. Overall, using less expensive, unrefined, virgin hemp seed oil versus more expensive, refined hemp seed oil did not appreciably affect the enzyme kinetics of the transesterification reactions nor the UV absorbing and antioxidant efficacy of the resultant feruloylated hemp seed oils, making FHO_V a less expensively produced feruloylated hemp seed oil for cosmetic and personal care applications.

There is growing research on developing new and sustainable lubricants. Sustainable lubricants with adequate cold-flow properties are of particular interest for many applications. One limitation of the established methods for measuring cold flow properties is the large volume needed to test samples. This makes initial screening of many hard-to-synthesize samples difficult. In the current study, we compared the results of the older, widely accepted ASTM methods D97 (pour point, PP) and D2500 (cloud point, CP) to the newer, smaller-volume, and easier-to-perform methods D5949 and D5773 for bio-based base oils (estolides and iso-estolides). The CP results were in good agreement for less colored samples, but D5773 gave lower values for some darker (Gardner color >8) samples, especially esters. The D5949 showed a tendency to report slightly higher PP, especially for the lower values. Viscosities and densities in a wide temperature range (15 to 120 °C) were also measured. The surface tensions were estimated by a literature group method. Viscosity and density effects can only partially explain the differences in the PP values from the two methods. In conclusion, the newer mini-methods are an acceptable substitution when larger volumes are not accessible, unless the sample is too dark.

Hydroxy fatty acids (HFAs) have long been a staple component of feedstock oils with uses ranging from motor oils to food to pharmaceuticals. Castor oil, which contains the HFA ricinoleic acid as its principal component, is the most widely used source of HFA in the world. In addition, bisphosphonates are a functional moiety that has been shown to display a variety of industrial applications, ranging from use in water softeners to osteoporosis drugs, primarily due to their affinity for the calcium ion. We have long been interested in the modification of ricinoleic acid from castor oil to phosphorus derivatives, including α‐hydroxy phosphonates and phosphonic acids, and have now accomplished the synthesis of a family of ricinoleic‐derived bisphosphonates: one that retains the cis alkene found in ricinoleic acid and one where the alkene has undergone hydrogenation. These compounds have been produced in high yields and high purity and the synthesis of these compounds is reported.

A new electrochemical catalyst has been synthesized from an analog of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and the medium chain fatty acid, undecenoic acid. The electrochemical properties of the new material are shifted to more positive potential by ∼170 mV, typical for other substituted TEMPOs. The straightforward reaction gives a catalyst that has been tested in the oxidation of alcohols to aldehydes and ketones and gives reaction rates similar to TEMPOs when considered on a per nitroxyl basis. However, the new system gives an ∼ 3‐fold higher primary over secondary selectivity. This reaction shows promise as a versatile method in the potential to synthesize rationally designed electroactive materials with a high biobased content.

Fatty epoxides are produced from the corresponding alkenes by oxidation in the presence of peracids or other oxidants. The classic method is the Prilezhaev epoxidation in which peracids are generated by in situ oxidation of formic or acetic acids with hydrogen peroxide. Epoxidized vegetable oils and esters are used directly as biobased plasticizers and stabilizers for poly(vinyl chloride) or as important platform chemicals for the oleochemical industry. Nucleophilic attack at the oxirane moiety affords a variety of ring opened monomeric or polymeric products, which in many cases undergo further synthetic modification to yield finished products. The most common nucleophiles include water, alcohols, carboxylic acids, acid anhydrides, and amines, although numerous others can also lead to valuable functionalized fatty derivatives. This review summarizes the chemistry of fatty epoxide ring opening reactions as well as applications of the resultant products. Literature from the last 20 years will be emphasized, although older publications of particular significance will be included. Important applications include biobased lubricants as well as polyols for subsequent production of polyurethanes. In addition, ring‐opening reactions hitherto unreported on fatty oxiranes will be suggested to facilitate further advancements in the chemistry and utility of fatty epoxides. Finally, interest in fatty epoxides and their consequent products will continue to grow due to the simplicity, efficiency, and versatility of oxirane formation and ring opening as well as the continued societal transition away from petroleum to a sustainable, circular, low‐carbon, and biobased economy.

BACKGROUND: Stable flies are one of the most detrimental arthropod pests to livestock. With changing climates and agronomic practices, they expand their roles as pests and disease vectors as well. Their painful bites reduce livestock productivity, annoy companion animals, and interfere with human recreational activities. Current management technologies are unable to effectively control stable flies. The present study reports new results concerning the contact, spatial repellency, and toxicity of a bio‐based product, coconut fatty acid and their methyl ester derivatives of free fatty acids of C_8:0, C_10:0 and C_12:0 to stable flies.RESULTS: Three medium chain fatty acid methyl esters (C_8:0, C_10:0 and C_12:0) showed strong antifeedant activity against stable flies and their strengths were dose‐dependent. Only the C_8:0 acid, C_8:0‐ and C_10:0 methyl esters elicited significant antennal responses. Laboratory single cage olfactometer bioassays revealed that coconut fatty acid and C_8:0 methyl ester displayed active spatial repellency. All three methyl esters showed strong toxicity against stable flies.CONCLUSION: Antifeedant activity is the main method through which coconut fatty acid deters stable fly blood‐feeding. The C_8:0, C_10:0 and C_12:0 methyl esters act not only as strong antifeedants, but also possess strong toxicity against stable fly adults. Limited spatial repellency was observed from coconut fatty acid and C_8:0 methyl ester. © 2019 Society of Chemical Industry