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.     

Genetic Encoding of a Photocaged Histidine for Light-Control of Protein Activity

The use of light to control protein function is a critical tool in chemical biology. Here we describe the addition of a photocaged histidine to the genetic code. This unnatural amino acid becomes histidine upon exposure to light and allows for the optical control of enzymes that utilize active-site histidine residues. We demonstrate light-induced activation of a blue fluorescent protein and a chloramphenicol transferase. Further, we genetically encoded photocaged histidine in mammalian cells. We then used this approach in live cells for optical control of firefly luciferase and, Renilla luciferase. This tool should have utility in manipulating and controlling a wide range of biological processes.     

A steady-state voltammetric procedure for the determination of hydrogen ions and total acid concentration in mixtures of a strong and a weak monoprotic acid

A linear sweep voltammetric (LSV) method for the simultaneous determination of free hydrogen ions and total concentration of the acids forming aqueous mixtures of a weak and a strong acid is proposed. The method is based on recording LSVs in the solutions investigated by a platinum microelectrode, and on the mathematical analysis of the voltammetric responses. In particular, the first derivative of the waves allows establishing the steady-state limiting currents due to hydrogen ions. Using the latter values, the overall LSV currents and a theoretical equation, which is valid for weak acids having dissociation constants higher than about 10⁻⁶, both hydrogen ions and total acid concentration can be evaluated. The validity and degree of accuracy of the proposed procedure is preliminarily assessed by digital simulation for mixtures of a strong acid and acetic acid (HAc). In general, an agreement between expected and evaluated (by the proposed method) concentration values within 2% is found. The proposed method is then tested in synthetic mixtures made by HClO₄ and HAc at different concentrations. An application to some vinegar samples is also presented to individuate if these matrices were adulterated by strong mineral acids. For these experimental cases, the concentrations values evaluated with the proposed method and those determined by the classical titration procedure agree within 4%.     

Extracting long-chain fatty acids from a fermentation medium

Several solvents were evaluated for extracting free long-chain FA (LCFA) from a fermentation medium. Chloroform, chloroform/methanol (1∶1), hexane, and hexane/methyl tert-butyl ether (MTBE) (1∶1) were evaluated as alternative extraction solvents. Parameters considered for optimizing LCFA recoveries included pH and ionic strength. Maximal LCFA recoveries were obtained by adding 2 mL of the hexane/MTBE (1∶1) solvent mixture, 80 μL of 50% H₂SO₄, and 0.05 g NaCl to 1 mL of the aqueous sample and mixing for 15 min at 200 rpm. This method quantified saturated LCFA [capric acid (C_10∶0) to stearic acid (C_18∶0)] and unsaturated LCFA with 18 carbons [linoleic acid (C_18∶2) and oleic acid (C_18∶1)] with a 98 to 100% recovery. Caproic (C_6∶0) and caprylic (C_8∶0) acids were characterized by 27 and 76% recoveries, respectively.     

Enantioselective Organocatalytic Synthesis of Arylglycines via Friedel–Crafts Alkylation of Arenes with a Glyoxylate Imine

The enantioselective organocatalytic synthesis of arylglycines has been developed employing 1 mol% of an enantiopure N‐triflyl phosphoramide Brønsted acid as organocatalyst. Various differently substituted phenylglycine derivatives can be synthesized in good to excellent yields and enantiomeric excesses based on a Friedel–Crafts alkylation of electron‐rich arenes with a glyoxylate imine. A novel protocol for the deprotection of the N‐tert‐butylsulfonyl (Bus) group has also been developed.     

Monolayer Packing of Submicrometer Ceramic Spheres by Employing a Langmuir–Blodgett Film of Dicarboxylic Acid

A closely packed monolayer of spherical SiO₂ or SiO₂–TiO₂ particles of submicrometer size has been fabricated on a silicon or glass substrate by employing a Langmuir–Blodgett (LB) film of 1,12-dodecanedicarboxylic acid, followed by dehydration–condensation reaction between carboxyl groups of the dicarboxylic acid and surface hydroxyl groups of both the substrate and the ceramic spheres. Deposition of the LB film on the substrate was essential for immobilization of ceramic spheres. The flexibility of an alkyl chain in the dicarboxylic acid may have resulted in better capturing of ceramic spheres compared with surface hydroxyl groups on the substrate. Two-dimensional packing of the ceramic spheres immobilized became dense with decreasing molecular area of the dicarboxylic acid in the LB film and the temperature of the LB medium (water), although partial three-dimensional attachment of ceramic spheres was observed, especially when an LB film of quite small molecular area was used. In addition, the amount of surface hydroxyl groups on the substrate was found to significantly affect the microstructure of the two-dimensionally packed ceramic spheres. The closest two-dimensional packing was observed on a glass substrate by employing an LB film with a molecular area of 0.03 nm²·molecule⁻¹ at 20°C.     

Determination of Nutritional and Cyclopropenoid Fatty Acids in Cottonseed by a Single GC Analysis

Historically, a complete analysis of cottonseed fatty acids required two separate analyses: gas chromatography (GC) for nutritional fatty acids and a separate analysis for cyclopropenoid fatty acids (CPFA). Using base esterification and optimized GC conditions, the method presented combines both analyses into a single GC procedure that improves analytical processes and streamlines workflow. While there were challenges, the resolution of critical pairs malvalic/stearic and dihydrosterculic/alpha linolenic methyl esters were adequately separated, allowing for accurate quantitation. Single lab reproducibility measurements (RSD) for major nutritional fatty acids ranged from 0.7 to 2.0 %. For CPFA the RSD ranged from 1.1 to 5.4 %, with the higher variability seen in the extracted cottonseed. In oils, the precision was similar between nutritional fatty acids and CPFA at equivalent concentrations, indicating the variation comes from the extraction process. Average spiked recovery results ranged from 93.3 to 106.5 % for selected fatty acids. In addition, complete fatty acid profile results compare favorably with other methodologies and historical data, demonstrating that it is possible to combine two legacy methods into one.     

Volatile fatty acids in flavors of potatoes deep-fried in a beef blend

The volatile free fatty acids were analyzed in commercial french- fried potatoes that had been deep- fried in beef tallow- hydrogenated vegetable oil shortening. The results showed that many of the volatile fatty acids present in beef tallow were transferred to the potatoes. Of the fatty acids derived from beef tallow, butanoic, 2-methylbutanoic, 3- methylbutanoic, heptanoic, 4-methyltanoic, and nonanoic acids were present in concentrations above their respective thresholds, and should contribute to tallow- like flavors. Several unsaturated volatile fatty acids also were identified, and they should contribute to the general deep- fried potato flavor.     

商榷一个在教学中遇到的问题

本文简要地讨论了五院校合编的教材中，酰胺与铵盐和腈的关系式，从而阐述了一个值的商榷的问题。     

Cancer as a Metabolic Disorder

Cancer has long been considered a genetic disease characterized by a myriad of mutations that drive cancer progression. Recent accumulating evidence indicates that the dysregulated metabolism in cancer cells is more than a hallmark of cancer but may be the underlying cause of the tumor. Most of the well-characterized oncogenes or tumor suppressor genes function to sustain the altered metabolic state in cancer. Here, we review evidence supporting the altered metabolic state in cancer including key alterations in glucose, glutamine, and fatty acid metabolism. Unlike genetic alterations that do not occur in all cancer types, metabolic alterations are more common among cancer subtypes and across cancers. Recognizing cancer as a metabolic disorder could unravel key diagnostic and treatments markers that can impact approaches used in cancer management.     

Production, Purification and Partial Characterization of Four Lipases from a Thermophile Isolated from Deception Island

Four lipases were purified from ID17, a thermophilic bacterium belonging to Geobacillus genus isolated from Deception Island, Antarctica. Lipase activity was detected by opacity test and p-nitrophenyl laurate methods. Lipase production was better in a medium containing tryptone as the carbon and nitrogen source, without non-ionic detergents and pH 7.5. Proteins were ultrafiltered from supernatant and separated using anion exchange and size exclusion chromatography resulting in four distinct fractions with lipase activity (called Lip1–4). Purified lipases showed an optimal pH at 9.0, 9.5, 10.0 and 8.0 and temperature at 65, 70, 75 and 80 °C for Lip1–4, respectively. Lip1 and Lip2 showed higher activity using p-nitrophenol decanoate as substrate, whereas Lip3 and Lip4 prefer p-nitrophenol laurate. Based on their molecular weight Lip1 and Lip2 are trimeric and pentameric proteins, respectively, whereas Lip3 and Lip4 are monomeric proteins. Lip1 was exceptionally thermostable maintaining 70 % of its activity after incubating it at 70 °C for 8 h. Based on their characteristics, the four lipases obtained from ID17 are good candidates to understand the mechanisms of lipase stability and to be used in different types of industrial applications.     

杂多酸(盐)催化新型香料草莓酯的合成

采用硅钨酸铝作催化剂 ,以乙酰乙酸乙酯和 1 ,2 丙二醇为原料合成草莓酯。优化的反应条件为 :0 2mol乙酰乙酸乙酯 ,0 2mol1 ,2 丙二醇 ,40ml环己烷 ,0 3 g硅钨酸铝 ,反应 3 5h ,草莓酯收率达 81 6%。产物经理化检验和红外光谱确证     

Amino acids profiles in a ph-auxostat

The proportions of amino acids changed dramatically in a pH-auxostat as the dilution rate was increased by feeding a medium with a low buffering capacity. A brief period of auxostatic culturing converts an elective mixed culture to a nearly pure culture, and this selection is accelerated by lowering the buffering capacity. As the specific growth rate was increased, the organisms utilized some of amino acids partially and/or completely, while others were essentially unchanged or even enriched. Such an enrichment effect was greatest at the highest specific growth rate.     

From a Racemate to a Single Enantiomer: Deracemization by Stereoinversion

The stereoinversion of one enantiomer into its mirror‐image counterpart within a racemate furnishes a single stereoisomeric product in 100 % theoretical yield. This extremely efficient type of deracemization, whereby substrate and product possess an identical chemical structure, can be achieved by using bio‐ or chemo‐catalysts or combinations thereof and is applicable to secondary alcohols, amines and α‐substituted carboxylic acids. Special emphasis is devoted to the theoretical background of the one‐pot, single‐step deracemization of sec‐alcohols.     

Epoxidation of a conjugated linoleic acid isomer

Epoxidation of methyl (9Z, 11E)‐octadecadienoate ( 1 ) with various epoxidizing agents viz. m‐chloroperoxybenzoic acid, dimethyl dioxirane, methyltrioxorhenium/hydrogen peroxide, potassium peroxomonosulfate (Oxone, 2KHSO₅ · KHSO₄ · K₂SO₄)/tetrahydrothiopyran‐4‐one, and Novozyme 435/hydrogen peroxide is described. The reactions furnished the corresponding mono‐epoxy [methyl (11, 12E)‐epoxy‐(9Z)‐octadecenoate ( 2 ) and methyl (9, 10Z)‐epoxy‐(11E)‐octadecenoate ( 3 )] and a mixture of diastereomers of syn‐ and anti‐diepoxy‐stearate [methyl (9, 10Z;11, 12E)‐diepoxystearate ( 4a‐4d )], which were identified by a combination of spectroscopic and spectrometric analyses.     

Fatty Acid Biomarkers of Symbionts and Unusual Inhibition of Tetracosapolyenoic Acid Biosynthesis in Corals (Octocorallia)

Seven zooxanthellae-free species of octocorals (the genera Acanthogorgia, Acabaria, Chironephthya, Echinogorgia, Menella, Ellisella, and Bebryce) and two zooxanthellate octocorals (the genera Paralemnalia and Rumphella) were examined to elucidate their fatty acid (FA) composition. Arachidonic (about 40% of the total FA) and palmitic acids were predominant in all the species studied. Seven furan FA (F-acids) (up to 9.7%) were identified in the azooxanthellate octocorals. The main F-acids were 14,17-epoxy-15-methyldocosa-14,16-dienoic and 14,17-epoxy-15,16-dimethyldocosa-14,16-dienoic acids. In all specimens of Bebryce studeri, C_25–28 demospongic FA (about 20%) were identified. These FA reflect the presence of a symbiotic sponge in B. studeri and can be used as the specific markers for other corals. A significant difference (P < 0.01) between azooxanthellate and zooxanthellate corals was found for odd-chain and methyl-branched saturated FA, 18:1n-7, and 7-Me-16:1n-10; that indicated the presence of an advanced bacterial community in azooxanthellate corals. The zooxanthellate species were distinguished by significant amounts of 18:3n-6, 18:4n-3, and 16:2n-7 acids, which are proposed as the markers of zooxanthellae in soft corals. Contrary to the normal level of 24:5n-6 (9.4%) and 22:4n-6 (0.6%), unexpected low concentrations of 24:5n-6 (0.4%) accompanied by a high content of 22:4n-6 (up to 11.9%) were detected in some specimens. The presence of an unknown factor in octocorals, specific for n-6 PUFA, which inhibited elongation of 22:4n-6 to 24:4n-6, is conjectured.     

羧酸类配位聚合物的研究进展

羧酸类金属配位聚合物是一种新型功能性分子材料,近年来得到科学家的普遍关注。本文对羧酸类金属配位聚合物的分类进行了综述,综述了羧酸类金属配位聚合物研究的重要性和国内外羧酸类金属配位聚合物的研究工作,对苯多羧酸类、吡啶羧酸类、草酸类、脂肪族二羧酸类配合物在手性拆分和催化、分子磁体、非线性光学方面的研究进行了详细介绍,列举了近年来这类配位聚合物的研究成果和开发进展,并对其发展趋势进行了展望。     

Willgerodt-Kindler法合成系列芳基乙酸化合物

以各种芳基乙酮为原料,通过Willgerodt-Kindler重排反应、水解反应合成了8个相应的芳基乙酸类化合物。通过2,4-二羟基苯乙酸的合成考察了反应时间、物料配比和水解过程对反应的影响。结果表明,重排反应最佳条件为:反应时间8 h,2,4-二羟基苯乙酮∶吗啉的物质的量比为1∶3.75。在此条件下,收率75%。     

A Practical Way to Prepare Isobutyronitrile Amides through Reactions between Carboxylic Acids and Azobisisobutyronitrile

A practical and efficient synthesis of N‐isobutyronitrile amides has been achieved through the direct condensation of carboxylic acid and azobisisobutyronitrile (AIBN). Carboxylic acids bearing variously substituted phenyl rings and cinnamic or phenylpropiolic acids were employed to furnish both tertiary and secondary isobutyronitrile amides in moderate to high yields. A radical pathway was proposed. The methodology presented here requires no catalysts and additives, and represents the first practical approach to a variety of valuable amides containing the isobutyronitrile structural unit.