The stereochemistry of fatty acid hydroxylation by cytochrome P450BM3

The stereochemical preference for the cytochrome P450_BM3-catalysed hydroxylation of tetradecanoic and pentadecanoic acids has been determined via comparison with authentic non-racemic standards utilising enantioselective HPLC. The sub-terminal hydroxylation of these fatty acids by P450_BM3 is highly selective for the formation of the R-alcohols. This is the same enantioselectivity as is seen for hexadecanoic acid oxidation but contrasts with a previous report of S-hydroxylation of pentadecanoic acid by P450_BM3.     

Separation of Hydroxylated Metabolites of Fatty Acids (C10-C18) on a μPorasil Silica Column Using an Isocratic HPLC System

Abstract

A simple, versatile, and rapid normal-phase isocratic HLPC system is described for the analysis of the major (omega and omega-1) metabolites of C₁₀-C₁₈ chain length fatty acids formed upon incubation with rat liver microsomes and NADPH. Quantitation was achieved by radiometric detection. Chromatographic separation was performed by elution of the fatty acids and their omega and omega-1 metabolites from a 10μ silica column (μPorasil) with hexane:2-propanol:acetic acid (96.5:2.5:1.0). Retention times for these metabolites ranged from 10 to 13 minutes for stearic acid and from 16 to 21 minutes for capric acid. Recovery of the fatty acids and their metabolites from the column was greater than 95 percent. Relative quantitative conversion of the fatty acid substrates to omega and omega-1 metabolites was in the following order: myristic acid > capric acid=lauric acid=palmitic acid ? stearic acid. The omega products were formed preferentially over the omega-1 products of all the fatty acids except lauric acid. The method proved suitable for routine determination of NADPH-dependent fatty acid hydroxylase activities in rat liver microsomes.     

An improved derivatization method for sensitive determination of fatty acids by high-performance liquid chromatography using 9-(2-hydroxylethyl)-carbazole as derivatization reagent with fluorescence detection

Summary Tagging techniques with reagents used for fluorescent detection for short and long-chain fatty acids using high-performance liquid chromatography are evaluated in terms of the tagging reactions, handing, flexibility, stability of the reagents. Emphasis is given to the applications of the tagging techniques to relatively high molecular mass fatty acids. The fatty acids or carboxylic compounds were derivatized to their corresponding esters with 9-(2-hydroxy ethyl)-carbazole (HEC) in acetonitrile at 60°C with N, N′-carbonyldiimidazole (CDI) as a coupling agent in the presence of 4-dimethylaminopyridine (DMAP). A mixture of esters of C₁−C₂₀ fatty acids was completely separated with 45 min using gradient elution on a reversed-phase C₁₈ column. The maximum fluorescence emission for the derivatized fatty acids is at 365 nm (λ_ex 293 nm). Studies on derivatization conditions indicated that fatty acids react rapidly and smoothly with HEC in the presence of CDI and DMAP in acetonitrile to give the corresponding sensitively fluorescent derivatives. The application of this method to the analysis of long chain fatty acids in plasma is also investigated. The LC separation shows good selectivity and reproducibility for fatty acids derivatives. The relative standard deviations (n=6) for each fatty acid derivative are <5.0%. The detection limits are at 38–57 fmol levels for C₁₄−C₂₀ fatty acids and lower levels for <C₁₄ fatty acids.     

Determination of fatty acids in atmospheric samples via GC/MS

Summary Atmospheric precipitation and aerosol samples are characterized by a complex mixture of several organic compounds. A simple method for the simultaneous determination of the main compound classes by GC/MS is presented. In detail, seasonal variations of C₈–C₃₂ fatty acids in precipitation in a semirural area have been studied. Total fatty acids concentrations of 7–53 g/l were detected. Summer rain is characterized by high amounts of fatty acids >C₂₀ and lower amounts of C₁₁–C₂₀ species. Two effects may be responsible: larger emission rates of fatty acids during vegetation periods and an increased influence of vapour phase due to higher temperatures during summer. CPI values showed no general trend; lower CPI values for winter rain could not be observed. This would be expected if anthropogenic sources play an important role. Monounsaturated fatty acids (C_16:1, C_18:1) were more abundant during winter than in summer. High concentrations of polyunsaturated fatty acids (C_18:x) could be detected during summer. High relative concentrations of the potential oxidation products of the unsaturated species, nonanedioic acid and w-oxononanoic acid, are associated with relatively low concentrations of their precursors.     

Study of the GC–MS determination of the palmitic–stearic acid ratio for the characterisation of drying oil in painting: La Encarnación by Alonso Cano as a case study

The correct identification of drying oils plays an essential role in providing an understanding of the conservation and deterioration of artistic materials in works of art. To this end, this work proposes the use of peak area ratios from fatty acids after ensuring that the linear responses of the detector are tested. A GC-MS method, previously reported in the literature, was revisited to its developed and validated in order to identify and quantify of eight fatty acids that are widely used as markers for drying oils in paintings, namely myristic acid (C_14:0), palmitic acid (C_16:0), stearic acid (C_18:0), oleic acid (C_18:1), linoleic acid (C_18:2), suberic acid (2C₈), azelaic acid, (2C₉) and sebacic acid (2C₁₀). The quaternary ammonium reagent m-(trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFAH) was used for derivatization prior to GC-MS analysis of the oils. MS spectra were obtained for each methyl ester derivative of the fatty acids and the characteristic fragments were identified. The method was validated in terms of calibration functions, detection and quantification limits and reproducibility using the signal recorded in SIR mode, since two of the methyl derivatives were not totally separated in the chromatographic run. The proposed method was successfully applied to identify and characterise the most widely used drying oils (linseed oil, poppy seed oil and walnut oil) in the painting La Encarnación. This 17th century easel painting is located in the main chapel of the cathedral in Granada (Spain) and was painted by the well-known artist of the Spanish Golden Age, Alonso Cano (1601-1667).     

Direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2

This paper described a mild and efficient direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp₂Cl₂. Arylacetic acid derivatives reacted with different amines to afford the corresponding amides in good to excellent yield except of aniline. Aryl formic acids failed to react with aniline but smoothly reacted with aliphatic amines and benzylamine in moderate to good yield, fatty acids reacting with benzyl and aliphatic amines give amides in good to excellent yield. Chiral amino acids derivatives were transformed into amides without racemization in moderate yield. The possible mechanism of direct amidation catalyzed by TiCp₂Cl₂ was discussed. This catalytic method is very suitable for the amidation of low sterically hindered arylacetic acid, fatty acids with different low sterically hindered amines except aniline, as well as the amidation of aryl formic acid with benzyl and aliphatic amines.     

A convenient method to reduce hydroxyl-substituted aromatic carboxylic acid with NaBH4/Me2SO4/B(OMe)3

The reduction of hydroxyl-substituted aromatic carboxylic acid with NaBH₄/Me₂SO₄/B(OMe)₃ is described. Borane is generated by the reaction of NaBH₄ with Me₂SO₄ in THF, which is as efficient as the commercial one. B(OMe)₃ has been successfully applied to increase the reactivity and selectivity of this reaction. The optimum ratio of borane/B(OMe)₃/acid is studied, and a variety of hydroxyl-substituted aromatic acids are reduced in good yields.     

大果白刺游离脂肪酸的柱前衍生高效液相色谱-荧光检测法分析

采用2-（11H-苯[a]咔唑）乙基对甲苯磺酸酯（BCETS）为柱前荧光衍生试剂,通过梯度洗脱使得18种脂肪酸在BDS-C8柱上得到良好的分离.方法应用于大果白刺不同部位中游离脂肪酸的分析,结果表明大果白刺的果皮果肉和叶子中均含有大量的不饱和脂肪酸,其总不饱和脂肪酸含量分别为70.74%和73.47%.大果白刺种子中不饱和脂肪酸的含量相对较少,仅占总脂肪酸含量的57.21%,其不饱和脂肪酸组成主要是C18∶1（油酸）和C18∶2（亚油酸）.其中,大果白刺的果皮果肉中,不饱和脂肪酸主要是C18∶1、C18∶2和C18∶3（亚麻酸）.其叶子中的不饱和脂肪酸主要是C18∶3,所占总脂肪酸比例为48.34%.首次对大果白刺中的脂肪酸进行了分析,可以为大果白刺在食品、药品中的进一步开发应用和质量控制提供一定的数据支持.     

Friedel-Crafts acylation of aromatic compounds with carboxylic acids in the presence of P2O5/SiO2 under heterogeneous conditions

A convenient and efficient procedure for the Friedel-Crafts acylation of aromatic compounds with carboxylic acids in the presence of P₂O₅/SiO₂ is described. Both aromatic and aliphatic carboxylic acids reacted easily to afford the corresponding aromatic ketones. The use of non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are the advantages of this method.     

A high hydroarylation activity of K2PtCl4/AgOTf catalyst in the reaction of propiolic acid with unactivated and activated arenes

A mixed catalyst K₂PtCl₄/AgOTf showed the highest activity for hydroarylation of propiolic acid, among palladium and platinum catalysts. This catalyst was effective for hydroarylation with less reactive benzene to give cis-cinnamic acid in good yield. The hydroarylation with toluene gave a higher yield of hydroarylation products than that with benzene and resulted in ortho/para orientation with an almost statistical ratio, suggesting that the result is very close to that of the Friedel-Crafts alkylation with methyl bromide or p-nitrobenzyl chloride. Hydroarylation of propiolic acid with other electron-rich arenes proceeded efficiently in the presence of the K₂PtCl₄/AgOTf catalyst in trifluoroacetic acid forming cis-cinnamic acids in good to high yields. This method was also applied to hydroarylation of ethyl propiolate.     

Surface properties of new virginiamycin M1 derivatives

Three kinds of derivatives of the M₁ factor of virginiamycin have been synthesised: esters with long chain fatty acids, oximes with modified polar amino acids and bis-derivatives with both the ester and oxime function. The study of the surface tension time dependence of M₁ and its derivatives has shown that it is necessary to enhance simultaneously the hydrophobicity and the hydrophilicity of M₁ to render M₁ surface-active. A structure/function relationship study of the surface-active bis-derivatives has shown that enhancing the hydrophobicity of the molecule led to slower adsorption kinetics, higher stability of the monolayers formed and a better capacity to penetrate a membrane model. The repulsive electrostatic forces due to the presence of charges on the amino acids linked to M₁ lead to higher surface tensions, a greater molecular area at the interface and lower penetration into a membrane model.This study has demonstrated that modifying systematically the hydrophobicity and hydrophilicity of a non surface-active molecule allows the production of surface-active derivatives.     

锰离子氧化沉淀法实现锂离子电池LiNi0.8Co0.05Mn0.15O2材料的回收和利用

以浓盐酸为浸出剂,以NaOH和NH₄HCO₃为沉淀剂,利用Mn²⁺在碱性条件下的氧化反应改变离子的沉淀次序进而分步回收的方案,探究了浓盐酸酸浸处理三元正极材料LiNi_0.8Co_0.05Mn_0.15O₂的最佳条件。在分步沉淀过程中,Mn²⁺被氧化为不溶于非还原性酸的MnO(OH)₂,并在酸性条件下回收。Ni、Co则在碱性条件下利用NaOH回收,而Li则利用NH₄HCO₃回收。该方法中Mn的回收率达到85.1%,产品纯度达到98.6%; Li的回收率达到95.0%,产品纯度达到99.3%。由回收材料重新合成的三元正极组装的软包电池的首圈放电比容量达到了175 mAh·g^-1,可以以超过99.5%的库仑效率稳定循环50圈。     

A rapid fluorometric assay for the determination of serum phospholipase A2 activity

Phospholipase A₂ (PLA₂) is an enzyme that cleaves fatty acids from the sn-2 position of membrane phospholipids. Intracellular PLA₂ has been shown to be important for the generation of arachidonic acid, which leads to the synthesis of a wide range of eicosanoid paracrine hormones. Furthermore, secretory PLA₂ in the serum has been reported to exhibit important immune activities. In this study, BODIPY™ FL C₁₆ was used as a fluorescent probe to measure PLA₂ activity in the serum of the American alligator. The activity measured was dependent on the amounts of serum and labeled bacteria incubated. The phospholipase activity was also time-dependent, with near peak activities observed within 20-30 min. In addition, the observed activity was titrated away by increasing concentrations of unlabeled bacteria, indicating that the activity observed was specifically due to the presence of PLA₂. The assay provides rapid results and requires only small amounts of serum.     

Pyridine-H5PMo10V2O40 hybrid catalysts for liquid-phase hydroxylation of benzene to phenol with molecular oxygen

Pyridine(Py)-modified Keggin-type vanadium-substituted heteropoly acids (Py _n PMo₁₀V₂O₄₀, n=1 to 5) were prepared by a precipitation method as organic/inorganic hybrid catalysts for direct hydroxylation of benzene to phenol in a pressured batch reactor and their structures were detected by FT-IR. Among various catalysts, Py₃PMo₁₀V₂O₄₀ exhibits the highest catalytic activity (yield of phenol, 11.5%), without observing the formation of catechol, hydroquinone and benzoquinone in the reaction with 80 vol% aqueous acetic acid, molecular oxygen and ascorbic acid used as the solvent, oxidant and reducing reagent, respectively. Influences of reaction temperature, reaction time, oxygen pressure, amount of ascorbic acid and catalyst on yield of phenol were investigated to obtain the optimal reaction conditions for phenol formation. Pyridine can greatly promote the catalytic activity of the Py-free catalyst (H₅PMo₁₀V₂O₄₀), mostly because the organic π electrons in the hybrid catalyst may extend their conjugation to the inorganic framework of heteropoly acid and dramatically modify the redox properties, at the same time, pyridine adsorbed on heteropoly acids can promote the effect of “pseudo-liquid phase”, thus accounting for the enhancement of phenol yield. Supported by the National Natural Science Foundation of China (Grant Nos. 20476046 and 20776069) and the “Qinglan” Project of Jiangsu Province for Young Researchers     

Solubility of selected dibasic carboxylic acids in water,in ionic liquid of [Bmim][BF4], and in aqueous [Bmim][BF4] solutions

The solubilities of three dibasic carboxylic acids (adipic acid, glutaric acid, and succinic acid) in water, in the ionic liquid of 1-butyl-3-methyl-imidazolim tetrafluoroborate ([Bmim][BF₄]), and in the aqueous [Bmim][BF₄] solutions have been measured by a solid-disapperance method. The binodal curve of water + [Bmim][BF₄] was also determined experimentally from solid–liquid–liquid coexistence temperature up to near the upper critical solution temperature. Experimental results showed that each acid-containing binary behaved as a simple eutectic system. The solid–liquid equilibrium (SLE) data were correlated with the NRTL model for each binary system. The NRTL model with these determined binary parameters predicted the solid-disappearance temperatures of the aqueous ternary mixtures containing [Bmim][BF₄] and the dibasic acids to within an average absolute deviation of 2.0%.     

Thermally produced ω-(o-alkylphenyl)alkanoic acids provide evidence for the processing of marine products in archaeological pottery vessels

ω-(o-Alkylphenyl)alkanoic acids with 16, 18 and 20 carbon atoms were identified in archaeological pottery vessels from coastal sites in Southern Brazil. Such compounds are presumed to form during heating of triunsaturated fatty acids (C_16:3, C_18:3 and C_20:3), which are commonly found in the tissues of marine animals. The detection of these unusual cyclic compounds together with the isoprenoid fatty acids, 4,8,12-trimethyltetradecanoic acid and phytanic acid and substantial quantities of archaeological bones of fish and mollusca, provides evidence for the processing of marine animal products in archaeological pottery.     

锰离子氧化沉淀法实现锂离子电池LiNi0.8Co0.05Mn0.15O2材料的回收和利用

以浓盐酸为浸出剂,以NaOH和NH₄HCO₃为沉淀剂,利用Mn²⁺在碱性条件下的氧化反应改变离子的沉淀次序进而分步回收的方案,探究了浓盐酸酸浸处理三元正极材料LiNi_0.8Co_0.05Mn_0.15O₂的最佳条件。在分步沉淀过程中,Mn²⁺被氧化为不溶于非还原性酸的MnO （OH）₂,并在酸性条件下回收。Ni、Co则在碱性条件下利用NaOH回收,而Li则利用NH₄HCO₃回收。该方法中Mn的回收率达到85.1%,产品纯度达到98.6%; Li的回收率达到95.0%,产品纯度达到99.3%。由回收材料重新合成的三元正极组装的软包电池的首圈放电比容量达到了175 mAh·g^-1,可以以超过99.5%的库仑效率稳定循环50圈。     

A simple, novel and convenient method for the synthesis of 1-aminophosphinic acids: synthesis of a novel C2-symmetric phosphinic acid pseudodipeptide

A simple, efficient and novel method has been developed for the synthesis of 1-aminophosphinic acids from simple starting materials. Treatment of aromatic aldehydes with ammonia and hypophosphorus acid gives novel C₂-symmetric 1-aminoarylmethylphosphinic acids. The synthesis of novel C₂-symmetric phosphinic acid pseudodipeptides is also discussed.     

Selective two-phase hydrogenation of sorbic acid using [Cp*Ru(sorbic acid)]+ catalyst?

Summary Unsaturated hexenoic acids are important compounds due to their utilization for specific aromatic alcohol (leaf alcohols) preparation. The influences of the reaction conditions on the sorbic acid hydrogenation to cis-hex-3-enoic acid are given. [Cp*Ru(sorbic acid)]CF₃SO₃ was used as a catalyst in two-phase hydrogenation.     

Nucleation activity of nanosized CaCO3 on crystallization of isotactic polypropylene, in dependence on crystal modification, particle shape, and coating

A detailed analysis of the effect of calcium carbonate nanoparticles on crystallization of isotactic polypropylene (iPP) is reported in this contribution. CaCO₃ nanoparticles with different crystal modifications (calcite and aragonite) and particle shape were added in small percentages to iPP. The nanoparticles were coated with two types of compatibilizer (either polypropylene-g-maleic anhydride copolymer, or fatty acids) to improve dispersion and adhesion with the polymer matrix.It was found that the type of coating agent used largely affects the nucleating ability of calcium carbonate towards formation of polypropylene crystals. CaCO₃ nanoparticles coated with maleated polypropylene can successfully promote nucleation of iPP crystals, whereas the addition of nanosized calcium carbonate coated with fatty acids delays crystallization of iPP, the effect being mainly ascribed to the physical state of the coating in the investigated temperature range for crystallization of iPP, as well as to possible dissolution by fatty acids of heterogeneities originally present in the polypropylene matrix.