New Environmentally Friendly Oxidative Scission of Oleic Acid into Azelaic Acid and Pelargonic Acid

Oleic acid (OA) is a renewable monounsaturated fatty acid obtained from high oleic sunflower oil. This work was focused on the oxidative scission of OA, which yields a mono-acid (pelargonic acid, PA) and a di-acid (azelaic acid, AA) through an emulsifying system. The conventional method for producing AA and PA consists of the ozonolysis of oleic acid, a process which presents numerous drawbacks. Therefore, we proposed to study a new alternative process using a green oxidant and a solvent-free system. OA was oxidized in a batch reactor with a biphasic organic-aqueous system consisting of hydrogen peroxide (H₂O₂, 30 %) as an oxidant and a peroxo–tungsten complex Q₃{PO₄[WO(O₂)₂]₄} as a phase-transfer catalyst/co-oxidant. Several phase-transfer catalysts were prepared in situ from tungstophosphoric acid, H₂O₂ and different quaternary ammonium salts (Q⁺, Cl^–). The catalyst [C₅H₅N(n-C₁₆H₃₃)]₃{PO₄[WO(O₂)₂]₄} was found to give the best results and was chosen for the optimization of the other parameters of the process. This optimization led to a complete conversion of OA into AA and PA with high yields (>80 %) using the system OA/H₂O₂/[C₅H₅N(n-C₁₆H₃₃)]₃{PO₄[WO(O₂)₂]₄} (1/5/0.02 molar ratio) at 85 °C for 5 h. In addition, a new treatment was developed in order to recover the catalyst.     

Liquid Phase Selective Catalytic Oxidation of Oleic Acid to Azelaic Acid Using Air and Transition Metal Acetate Bromide Complex

Industrially important di‐carboxylic acids are synthesized from mono‐carboxylic unsaturated and unsaturated fatty acids. In this study, the aim is to perform the simultaneous catalytic oxidative C=C cleavage of oleic acid (OA) to azelaic acid and pelargonic acid, and oxidation of the terminal methyl group in pelargonic acid to azelaic acid using cobalt‐ and manganese‐acetate as catalyst, hydrogen bromide as co‐catalyst and air in acetic acid at elevated pressure (2.8–5.8 barg) and temperature (353–383 K). Oxygen solubility is determined under varying pressure, temperature and OA loading. The effect of OA loading, pressure and temperature on OA conversion and azelaic acid selectivity is studied by varying one variable at a time; however, the presence of the synergistic effect of the catalyst and co‐catalyst is investigated by central composite design assisted response surface methodology. Oxidation of terminal methyl group in saturated fatty acid is also confirmed by the oxidation of stearic acid to octadecanedioic acid using identical oxidation conditions of OA. Oxidation products of fatty acids are quantified by gas chromatographic analysis. The innovation of the work is thus the ability of the catalytic system to perform a total oxidation of a terminal methyl group of the hydrocarbon chain. OA oxidation kinetics relating to catalyst and co‐catalyst concentration along with oxygen solubility at elevated temperature and pressure is established. The frequency factor and activation energy for OA oxidation is determined using the Arrhenius equation.     

Sustainable Oxidative Cleavage of Vegetable Oils into Diacids by Organo-Modified Molybdenum Oxide Heterogeneous Catalysts

Exploiting vegetable oils to produce industrially valuable diacids via an eco‐friendly process requires an efficient and recyclable catalyst. In this work, a novel catalytic system based on organo‐modified molybdenum trioxide was synthesized by a green hydrothermal method in one simple step, using Mo powder as precursor, hydrogen peroxide, and amphiphilic surfactants cetyltrimethylammonium bromide (CTAB) and tetramethylammonium bromide (TMAB) as capping agents. The synthesized materials were first characterized by different techniques including XRD, SEM, TGA, and FT‐IR. Interestingly, various morphologies were obtained depending on the nature of the surfactants and synthetic conditions. The synthesized catalysts were employed in oxidative cleavage of oleic acid, the most abundant unsaturated fatty acid, to produce azelaic and pelargonic acids with a benign oxidant, H₂O₂. Excellent catalytic activities resulting in full conversion of initial oleic acid were obtained, particularly for CTAB‐capped molybdenum oxide (CTAB/Mo molar ratio of 1:3) that gave 83 and 68% yields of production of azelaic and pelargonic acids, respectively. These are the highest yields that have been obtained for this reaction by heterogeneous catalysts up to now. Moreover, the CTAB‐capped catalyst could be conveniently separated from the reaction mixture by simple centrifugation and reused without significant loss of activity up to at least four cycles.     

Übergangsmetallkatalysierte Oxidationen ungesättigter Fettsäuren — Synthesen von Keto- und Dicarbonsäuren

Transition-metal Catalyzed Oxidation of Unsaturated Fatty Acids — Synthesis of Ketocarboxylic Acids and Dicarboxylic Acids Terminal unsaturated C₁₀–C₁₄-fatty acid methylesters (9-decenoic-, 10-un-decenoic-, 13-tetradecenoic methylesters) were converted to methylketocarboxylic methylesters (yields: 60–75%, isolated) by oxidation with O₂/H₂O at roomtemperature under catalysis of PdCl₂/CuCl₂. Using RhCl₃/FeCl₃ at 80°C yields of 40–60% were obtained. For the first time methyl oleate was converted directly to a mixture of 9-oxo- and 10-oxo-stearic acid methylester by palladium catalyzed oxidation. In DMF/H₂O the selectivity to these two ketoesters was 85% (15% isomers), in dioxane/H₂O the selectivity droped to 55% while the yield of the oxostearic acid esters climbed to 70%. The Mn-catalyzed oxidative cleavage of methylketocarboxylic acid esters with O₂ at 115°C led in each case to a mixture of two dicarboxylic acid esters in a molar ratio of 2 : 1. Starting with 9-oxodecanoic acid azelaic and suberic acid were obtained at a conversion rate of 90%. Analogous 10-oxoundecanoic acid led to C₁₀/C₉- and 13-oxotetradecanoic acid led to C₁₃/C₁₂-dicarboxylic acids. The oxidative cleavage of 9-/10-oxostearic acid methylester yielded mixtures of C₈–C₁₀-monocarboxylic acids and methylesters of C₈–C₁₀-dicarboxylic acids.     

Gold‐catalyzed synthesis of dicarboxylic and monocarboxylic acids

Vicinal dihydroxy derivatives of oleic acid, methyl oleate, and erucic acid were converted by oxidative cleavage to the respective di‐ and monocarboxylic acids according to an environmentally benign process carried out in the presence of supported gold catalysts and molecular oxygen as oxidant in an aqueous‐basic medium. Au(0) nanoparticles with particle sizes between 0.5 and 4.1 nm were deposited as catalytically active species on different oxidic supports. The influence of the catalyst composition and morphology as well as of the reaction conditions on conversion of dihydroxy fatty acids and yields of products were investigated. Thus, the reaction of 9,10‐dihydroxystearic acid catalyzed by Au/Al₂O₃ leads to azelaic acid (86% yield) and pelargonic acid (99% yield).     

Study of Mono-(2-ethylhexyl) Phosphoric Acid and Neutral Organophosphorus Synergists for Extraction of Uranium from Phosphoric Acid Solution

Abstract

The distribution of uranium(IV) and uranium(VI) between phosphoric acid solution and mono-(2-ethylhexyl) phosphoric acid (H₂MEHP)-trioctyl phosphine oxide (TOPO), and mono-(2-ethylhexyl) phosphoric acid-dibutyl butyl phosphonate (DBBP) in kerosene diluent has been investigated. The effects of extractant composition, phosphoric acid concentration, temperature, uranium concentration, and shaking time on the uranium extraction have been examined. Reductive extraction and oxidative stripping processes for the separation and concentration of uranium from phosphoric acid solution with synergic systems of H₂MEHP-TOPO and H₂MEHP-DBBP are proposed and discussed.     

A New HPLC-MS Method for Measuring Maslinic Acid and Oleanolic Acid in HT29 and HepG2 Human Cancer Cells

Maslinic acid (MA) and oleanolic acid (OA), the main triterpenic acids present in olive, have important properties for health and disease prevention. MA selectively inhibits cell proliferation of the HT29 human colon-cancer cell line by inducing selective apoptosis. For measuring the MA and OA concentration inside the cell and in the culture medium, a new HPLC-MS procedure has been developed. With this method, a determination of the amount of MA and OA incorporated into HT29 and HepG2 human cancer-cell lines incubated with different concentrations of MA corresponding to 50% growth inhibitory concentration (IC₅₀), IC_50/2, IC_50/4, and IC_50/8 has been made. The results demonstrate that this method is appropriate for determining the MA and OA concentration in different types of cultured cells and reveals the specific dynamics of entry of MA into HT29 and HepG2 cells.     

超声波辅助高锰酸钾法合成壬二酸

以油酸为原料,高锰酸绅为氧化剂,经氧化分解、沸水萃取、活性炭吸附脱色等过程制备壬二酸的最佳反应条件为:n(油酸)/n(高锰酸钾)=0.2:1～0.25:1,温度为50℃,m(油酸)/m(苄基三乙基氯化氨)=10:1,氧化10h,壬二酸收率大约为35％;在此条件下,增加超声波辅助手段,收率增加了10％～ 16％左右,壬二酸收率可达到50％.     

Catalytic Oxidation of Oleic Acid in Supercritical Carbon Dioxide Media with Molecular Oxygen

Oxidation of oleic acid was performed over various ordered porous catalysts containing transition metal in supercritical carbon dioxide (scCO₂) media with molecular oxygen. Oleic acid was completely decomposed into mono- and dicarboxylic acids over porous catalysts, viz., mesoporous molecular sieves (CrMCM-41, MnMCM-41, CoMCM-41) and microporous molecular sieves (CrAPO-5, CoMFI, MnMFI) using scCO₂ at 353 K for 8 h. Among the different catalysts studied, microporous and mesoporous catalysts containing chromium, in presence of scCO₂ showed high distribution of azelaic and pelargonic acids as compared to their analogs containing cobalt or manganese. The presence of scCO₂ medium with the catalysts increased the distribution of azelaic and pelargonic acids. The effect of CO₂ pressure, reaction temperature and reaction time on oxidation of oleic acid over CrMCM-41 was also investigated. Additionally it is noticed that the catalyst can be recycled with negligible loss of catalytic activity.     

Intensification of the Sulfuric Acid Alkylation Process with Trifluoroacetic Acid

H₂SO₄ alkylation of isobutane and butene is one of the primary commercial processes used to produce alkylates. This work presents a technology for the intensification of sulfuric acid alkylation with the addition of trifluoroacetic acid (TFA). The addition of TFA increased the solubility of isobutane in H₂SO₄, decreased its viscosity, and adjusted the acidity of H₂SO₄. With the addition of TFA, the selectivity of C8 was dramatically improved from 36.8 to 95.7%. The TFA content, stirring speed, reaction temperature, volume ratio of acid to hydrocarbon (H/C), molar ratio of isobutane to 2-butene (I/O), reaction time, and reuse of H₂SO₄/TFA were also investigated in this work. Compared with the conventional process, the new technology provided a considerably higher quality alkylation with considerably lower energy consumption. © 2018 American Institute of Chemical Engineers AIChE J, 65: 113–119, 2019     

Synthesis and Structure Characterization of Some Triorganotin Esters of Heteroaromatic Carboxylic Acid and Crystal Structure of Triphenyltin Esters of 6-Hydroxynicotinic Acid and 5-Chloro-6-hydroxynicotinic Acid

Reactions of (R₃Sn)₂O (R=Ph, 2-ClC₆H₄CH₂, 2-FC₆H₄CH₂, 4-CNC₆H₄CH₂) with 6-hydroxynicotinic acid and 5-chloro-6-hydroxynicotinic acid in 1:2 stoichiometry yielded eight triorganotin compounds. These compounds have been characterized by elemental analysis, IR and ¹H NMR spectroscopy. The crystal structures of triphenyltin esters of 6-hydroxynicotinic acid (1) and 5-chloro-6-hydroxynicotinic acid (2) were determined by single crystal X-ray diffraction. In these two compounds the tin atoms are rendered five-coordinate in a trigonal bipyramidal structure by coordination though the three phenyl carbon atoms and two oxygen atoms, one from carboxylate and other from the phenolic hydroxide. The resulting structures are two one-dimensional linear polymers through an interaction between the O atoms of phenolic hydroxide and tin atoms of an adjacent molecule.     

Production of Propene from n-Butanol: A Three-Step Cascade Utilizing the Cytochrome P450 Fatty Acid Decarboxylase OleTJE

Propene is one of the most important starting materials in the chemical industry. Herein, we report an enzymatic cascade reaction for the biocatalytic production of propene starting from n-butanol, thus offering a biobased production from glucose. In order to create an efficient system, we faced the issue of an optimal cofactor supply for the fatty acid decarboxylase OleT_JE, which is said to be driven by either NAD(P)H or H₂O₂. In the first system, we used an alcohol and aldehyde dehydrogenase coupled to OleT_JE by the electron-transfer complex putidaredoxin reductase/putidaredoxin, allowing regeneration of the NAD⁺ cofactor. With the second system, we intended full oxidation of n-butanol to butyric acid, generating one equivalent of H₂O₂ that can be used for the oxidative decarboxylation. As the optimal substrate is a long-chain fatty acid, we also tried to create an improved variant for the decarboxylation of butyric acid by using rational protein design. Within a mutational study with 57 designed mutants, we generated the mutant OleT_V292I, which showed a 2.4-fold improvement in propene production in our H₂O₂-driven cascade system and reached total turnover numbers >1000.     

Oxidative and Molecular Responses in Capsicum annuum L. after Hydrogen Peroxide,Salicylic Acid and Chitosan Foliar Applications

Hydrogen peroxide (H₂O₂) is an important ROS molecule (Reactive oxygen species) that serves as a signal of oxidative stress and activation of signaling cascades as a result of the early response of the plant to biotic stress. This response can also be generated with the application of elicitors, stable molecules that induce the activation of transduction cascades and hormonal pathways, which trigger induced resistance to environmental stress. In this work, we evaluated the endogenous H₂O₂ production caused by salicylic acid (SA), chitosan (QN), and H₂O₂ elicitors in Capsicum annuum L. Hydrogen peroxide production after elicitation, catalase (CAT) and phenylalanine ammonia lyase (PAL) activities, as well as gene expression analysis of cat1, pal, and pathogenesis-related protein 1 (pr1) were determined. Our results displayed that 6.7 and 10 mM SA concentrations, and, 14 and 18 mM H₂O₂ concentrations, induced an endogenous H₂O₂ and gene expression. QN treatments induced the same responses in lesser proportion than the other two elicitors. Endogenous H₂O₂ production monitored during several days, showed results that could be an indicator for determining application opportunity uses in agriculture for maintaining plant alert systems against a stress.     

Synthesis, Structures and Luminescent Properties of Two New Cd(II) Coordination Polymers Based on V-Shaped 3,3′,4,4′-Oxidiphthalic Acid

Two new Cd(II) coordination polymers, namely [Cd₂(H₂OA)₂(μ₂-H₂O)(H₂O)₆] _n ·3nH₂O (1) and [Cd₂(H₂OA)(phen)₂] _n ·nH₂O (2) (H₄OA = 3,3′,4,4′-oxidiphthalic acid, phen = 1,10-phenanthroline) have been synthesized by combining H₄OA or H₄OA and phen with Cd(II) salts under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 features a hydrogen-bond directed two-dimensional (2D) layered structure constructed from alternating left- and right-handed double strand helical chains, 2 represents a one-dimensional (1D) chain structure with the phen molecules dangling on it, which is further extended into a three-dimensional (3D) supramolecular framework through strong face-to-face π···π interactions. In addition, luminescent properties of these two compounds were also investigated in the solid state at room temperature.     

Preparation and characterization of ferrous oxalate cement—A novel acid-base cement

Ferrous oxalate cement (FOC), a new type of acid-base cement, is prepared at room temperature through reactions between iron-rich copper slag (CS) and oxalic acid (OA). In this work, the influences of precursor proportions, including the copper slag-to-oxalic acid mass ratio (CS/OA), borax-to-cement mass ratio (B/C), and water-to-cement mass ratio (W/C), on the setting behavior and compressive strength of FOC paste are investigated. Furthermore, the evolutions of pH and ions concentrations are traced to understand the reaction mechanism of FOC. The results show that the compressive strength decreases with an increase in W/C; when W/C is fixed, with an increase in CS/OA, the compressive strength first increases and then decreases, giving an optimal value. The compressive strengths of specimens at 3, 7, and 28 days can reach 33, 41, and 55 MPa, respectively, under the optimal conditions (CS/OA = 3.6, B/C = 0.03, and W/C = 0.18). The setting time is also a function of W/C and CS/OA, and can be extended by adding borax. Iron oxalate hydrate (FeC₂O₄·2H₂O) has been identified as the exclusive hydration product of FOC due to the chemical reaction between Fe₂SiO₄ or Fe₃O₄ contained in CS and OA solution. At the initial stage of reaction, OA is dissolved to release protons, HC₂O₄⁻ and C₂O₄²⁻, which facilitate the dissolution of Fe₂SiO₄ and Fe₃O₄ and the release of Fe²⁺ in the aqueous phase. Then the Fe²⁺ ions combine with HC₂O₄⁻ and C₂O₄²⁻ to precipitate FeC₂O₄·2H₂O, acting as the cementitious phase to bond the unreacted CS particles.     

Isomerization and Arylation of Oleic Acid on Anion Modified Zirconia Catalysts

The catalytic performance of anion modified zirconia catalysts, such as sulfated zirconia (SO₄/ZrO₂) and tungstated zirconia (WO₃/ZrO₂), was evaluated for the upgrading of oleic acid (OA). In the presence of an aromatic compound, two main reactions occurred on the catalysts: the skeletal isomerization of OA and the arylation of OA with aromatics. The activity of the SO₄/ZrO₂ was more than triple of that of the WO₃/ZrO₂. At 250 °C, OA/(SO₄/ZrO₂)(wt/wt) = 5, the OA conversion and the arylation selectivity reached their maximal values and the isomerization selectivity was the lowest when the toluene to OA (toluene/OA) molar ratio was about 6. When mesitylene was used instead of toluene, the OA conversion and the arylation selectivity decreased, probably because of a steric effect. An attempt to reuse the SO₄/ZrO₂ by solvent washing after a run was not so successful, while calcination at 630 °C in air recovered the activity completely.     

Electrochemical preparation of peroxodisulfuric acid using boron doped diamond thin film electrodes

We have investigated the electrochemical oxidation of sulfuric acid on boron-doped synthetic diamond electrodes (BDD) obtained by HF CVD on p-Si. The results have shown that high current efficiency for sulfuric acid oxidation to peroxodisulfuric acid can be achieved in concentrated H₂SO₄ (>2 M) at moderate temperatures (8-10 °C). The main side reaction is oxygen evolution. Small amounts of peroxomonosulfuric acid (Caro's acid) have also been detected. A reaction mechanism involving hydroxyl radicals, HSO₄⁻ and undissociated H₂SO₄ has been proposed. According to this mechanism electrogenerated hydroxyl radicals at the BDD anode react with HSO₄⁻ and H₂SO₄ giving peroxodisulfate.     

2-thiobarbituric acid test for lipid oxidation in food: Synthesis and spectroscopic study of 2-thiobarbituric acid-malonaldehyde adduct

Synthesis, purification, elemental analysis, and spectroscopic studies were undertaken to characterize the structure of the red adduct 2:1 thiobarbituric acid (TBA)-malonaldehyde involved in the evaluation of oxidative rancidity in fats and oils. Thin-layer chromatography, infrared and ultravioletvisible absorption, ¹H (¹H NMR) and ¹³C nuclear magnetic resonance (NMR) spectra were used. A yield of 93% was obtained in the synthesis. The results of elemental analysis agree with the formula for the chloro-monohydrated form, C₁₁H₁₁N₄O₅S₂Cl. Three characteristic absorption maxima at 532, 310, and 245 nm, respectively, were shown in acid aqueous medium (pH 2.9). The characteristic vibrations assigned to the -NH, -OH, C^αH (exocyclic) and -C=S groups were confirmed in the infrared spectra. There was no evidence of thioenolization. ¹H NMR data at δ 5.10 (-CONH- group, H₂O and HCl molecules); δ 11.54 (-OH group of keto-enol tautomer, -NH group); and δ 176.4 (-CONH- group) also were observed. The experimental results obtained were consistent with the existence of two spectral equivalent tautomeric structures. The colored adduct was compared with other TBA-aldehyde compounds.     

DNA cleavage activities and mechanism of a novel heterodinuclear macrocyclic complex

A new unsymmetrical bis-furan pendant-armed macrocyclic heterodinuclear Cu(II)Zn(II) complex, [CuZnL(OAc)](ClO₄)·3MeCN·H₂O(1) (H₂L was derived from the condensation between 1,6-bis(2-furyl)-2,5-bis(2-hydroxy-3-formyl-5-bromobenzyl)-2, 5-diazahexane and 1,3-diaminopropane), has been synthesized and characterized by EDS (energy dispersive spectroscopy) and X-ray crystallography determination. The interaction between the complex and calf thymus (CT) DNA was investigated by UV–vis absorption, viscosity experiment, fluorescent and CD spectroscopy. The mechanism of the cleavage of supercoiled DNA (pBR 322DNA) process was also studied. It is proposed that DNA cleavage promoted by the complex occurrence via oxidative mechanism.     

Purification of Wet‐Process Phosphoric Acid by Hydrogen Peroxide Oxidation,Activated Carbon Adsorption and Electrooxidation

In this work, three technologies are studied for the purification of phosphoric acid produced by the wet process: chemical oxidation with hydrogen peroxide, adsorption onto activated carbon, and electrochemical oxidation by boron‐doped diamond anodes. The treatment of wet‐process phosphoric acid by chemical oxidation with H₂O₂ as oxidizing agent can remove 75 % of the initial TOC as maximum, indicating that this wet‐process phosphoric acid contains an important amount of organics that cannot be oxidized by hydrogen peroxide under the operation conditions used. High temperatures and hydrogen peroxide/TOC ratios close to 150 g H₂O₂/g TOC allow obtaining the best chemical oxidation results. The adsorption onto activated carbon can remove between 40 and 60 % of the initial TOC as maximum. Adsorption times of 2 hours and activated carbon/WPA ratios close to 12 g AC/Kg WTP assure both steady state and maximum adsorption of organics. The electrochemical process is the only technique by which complete mineralization of WPA organics can be achieved. Operating at 60 mA cm^–2 and at room temperature, high current efficiencies are achieved which only seem to decrease by mass transport limitations.