Metathese ungesättigter Fettsäureester – ein einfacher Zugang zu langkettigen Dicarbonsäuren

Metathesis of Unsaturated Fatty Acid Esters – a Simple Approach to Long-Chained Dicarboxylic Acids Long-chained, symmetric unsaturated C₁₈-, C₂₀- und C₂₆-dicarboxylic acid esters are easily accessible from natural fatty acid esters by metathesis in a two-step procedure. In the first step unsaturated fatty acid esters are cleaved by metathesis with ethylene. Pure oleic acid ester or fatty acid methylesters, produced from high-oleic sunflower oil or from rapeseed oil by transesterification with methanol, are converted to 1-decene and 9-decenoic acid methylester. From erucic acid methylester 1-decene and 13-tetradecenoic acid methylester are achieved. Using our newly developed high efficient catalytic system B₂O₃-Re₂O₇/Al₂O₃-SiO₂ + SnBu₄ conversion rates of 86 – 96% are obtained and the terminally unsaturated fatty acid esters are isolated in yields of 61 – 83%. In the second step 9-decenoic and 13-tetradecenoic acid methylester as well as 10-undecenoic methylester, which is commercially obtained by pyrolysis of ricinoleic acid ester, are converted to 9-octadecenedioic-, 13-hexacosenedioic- and 10-eicosenedioic acid dimethylester, by which process ethylene is eliminated. The conversion rates are 89 – 99% and the dicarboxylic acid dimethylesters are isolated in yields of 77 – 84%.     

Acid properties of solid acid from petroleum coke by chemical activation and sulfonation

A novel solid acid was prepared from petroleum coke by KOH chemical activation and concentrated H₂SO₄ sulfonation. The solid acid was characterized by XRD, FT-IR and solid-state NMR. The characterization results show that the chemical activation and sulfonation lead to three functional Brønsted acid sites: –OH, –COOH and –SO₃H on the solid acid. The probe molecules experimental reveal that the acid strength of the solid acid is stronger than that of SO₄²⁻ /ZrO₂, but slightly weaker than that of 100% H₂SO₄. The catalytic performance was evaluated by the esterification of oleic acid with methanol. The results indicate that this solid acid catalyst is very active, corresponding to high conversion (72%) of esterification reaction. In addition, the spent solid acid can be recovered by simple regeneration process.     

p-Arsanilic acid stabilizing titanium-oxo clusters with various core structures and light absorption behaviours

A series of p-arsanilic acid stabilizing polyoxo‑titanium clusters (PTCs) have been successfully synthesized through solvothermal method, which present {Ti₄}, {Ti₅} and {Ti₆} cores functionalized by different carboxylic acid ligands. PTC-111 displays a {Ti₄} core structure which is stabilized by glycolic acid and esterified p-arsanilic acid. PTC-112, PTC-113 and PTC-114 have isostructural {Ti₆} structures, functionalized by isonicotinic acid, 2-chloroisonicotinic acid and benzoic acid, respectively. The {Ti₅} core of PTC-115 is functionalized by m-nitrobenzoic acid. It is interesting that the light absorption behaviours of these PTCs are dependent on their core structures and the functionalizing ligands.     

Effect of fuel type on structural and physicochemical properties of solution combustion synthesized CoCr2O4 ceramic pigment nanoparticles

Due to importance and wide applications, CoCr₂O₄ ceramic pigment nanoparticles were synthesized via low-temperature solution combustion route by different fuels including ethylenediamine/oxalic acid, ethylenediamine/citric acid, oxalic acid/citric acid and ethylenediamine/oxalic acid/citric acid. Physicochemical properties of the synthesized samples were determined by different techniques such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX) and color/optical properties were evaluated based on CIELAB system by spectrophotometer. Moreover, thermodynamic considerations of combustion reactions for CoCr₂O₄ nanopigments formation in terms of calculated adiabatic flame temperature and enthalpy of combustion reaction were studied. The Comparison of results and data showed that cobalt chromite pigment nanoparticles synthesized by using ethylenediamine/citric acid and ethylenediamine/oxalic acid/citric acid fuels exhibited higher purity, smaller crystallite size and lower degree agglomeration.     

Novel promoting effect of acid modification on selective catalytic reduction of NO with ammonia over CeO2 catalyst

A series of acid modified CeO₂ catalysts were prepared and used for selective catalytic reduction (SCR) of NO with NH₃. The results showed that the SCR activity of pure CeO₂ was greatly enhanced by the modification of acid. The CeO₂ modified by 20% phosphotungstic acid exhibited the best NO conversion in a wide temperature range of 150–550 °C. The SCR activity was slightly influenced by SO₂ and H₂O, while such effect was reversible. The improvement of SCR activity and N₂ selectivity over CeO₂ catalyst modified by acid was attributed to the enhanced amount and intensity of Brønsted or Lewis acid sites.     

The origin of palmitic acid in brain of the developing rat

A rat milk substitute containing lower amounts of palmitic and oleic acid in the triacylglycerols in comparison to natural rat milk was fed to artificially reared rat pups from day 7 after birth to day 14. Pups reared by their mother served as controls. Free trideuterated (D₃) palmitic acid [(C²H₃)(CH₂)₁₄COOH, 98 atom % D] and free perdeuterated (D₃₁) palmitic acid [C₁₅ ²H₃₁COOH, 99 atom % D] in equal quantity were mixed into the triacylglycerols of the milk substitute in an amount equal to 100% of the palmitic acid in the triacylglycerols. A control milk substitute contained unlabeled free palmitic acid in an amount equal to 100% of the palmitic acid in the triacylglycerols of the milk substitute. The objective was to determine if palmitic acid in the diet contributed significantly to the palmitic acid content of developing brain and other organs. The methyl esters of the fatty acids were analyzed by gas chromatography and the palmitic acid methyl ester was examined by fast atom bombardment mass spectrometry. The proportion of deuterated methyl palmitate as a percentage of total palmitate was determined; 32% of the palmitic acid in liver and 12% of the palmitic acid in lung were trideuterated and perdeuterated palmitic acid in approximately equal amounts. The brain, by contrast, did not contain the deuterated palmitic acid moiety. Quantitation of palmitic acid and total fatty acids revealed a significant accumulation in organs in the interval from 7 to 14 days of age. Under our experimental conditions, labeled palmitic acid does not enter the brain. Consequently, we conclude that the developing brain produces all required palmitic acid byde novo synthesis.     

Novel method to synthesis of single phase zirconolite ceramic

Single phase zirconolite (CaZrTi₂O₇) was synthesised by a novel method using acid corrosion to treat zirconolite–diopside mixture powders (2CaZrTi₂O₇–Mg2Si₂O₆). The mixture powders were prepared by solid state reaction method at 1200°C for 2 h. Single phase zirconolite powders were obtained by acid corrosion method with 5% hydrofluoric acid on the zirconolite–diopside Synroc mixture powders and washed with 10% acetic acid.     

Phytanic acid α-hydroxylation by bacterial cytochrome P450

Fatty acid α-hydroxylase, a cytochrome P450 enzyme, from Sphingomonas paucimobilis, utilizes various straight-chain fatty acids as substrates. We investigated whether a recombinant fatty acid α-hydroxylase is able to metabolize phytanic acid, a methyl-branched fatty acid. When phytanic acid was incubated with the recombinant enzyme in the presence of H₂O₂, a reaction product was detected by gas chromatography, whereas a reaction product was not detected in the absence of H₂O₂. When a heat-inactivated enzyme was used, a reaction product was not detected with any concentration of H₂O₂. Analysis of the methylated product by gas chromatography-mass spectrometry revealed a fragmentation pattern of 2-hydroxyphytanic acid methyl ester. By single-ion monitoring, the mass ion and the characteristic fragmentation ions of 2-hydroxyphytanic acid methyl ester were detected at the retention time corresponding to the time of the product observed on the gas chromatogram. The K _m value for phytanic acid was approximately 50 μM, which was similar to that for myristic acid, although the calculated V _max for phytanic acid was about 15-fold lower than that for myristic acid. These results indicate that a bacterial cytochrome P450 is able to oxidize phytanic acid to form 2-hydroxyphytanic acid.     

The determination of lactic acid in shortening containing lactylated glycerides,by liquid-liquid partition chromatography

Shortenings containing ca. 1% lactic acid added as lactylated glycerides are analyzed for total or water insoluble combined lactic acid (WICLA) by a liquid-liquid partition Chromatographie pro-cedure. The sample is saponified, acidified with H₂SO₄, dispersed on silicic acid, slurried with chloroform and transferred to the top of a chro-matographic column composed of a 0.5 N sulfuric acid stationary phase supported on silicic acid. After elution of the fatty acids by chloroform, 15% m-butanol removes the excess H₂SO₄ fol-lowed by a well resolved lactic acid fraction. Titration of the latter fraction with standard methanolic sodium hydroxide has shown the lactic acid recovery to be 94%. The WICLA determina-tion requires 7 hr and has a standard deviation of ±0.020%. Presented in part at the AOCS Meeting, New Orleans, 1962.     

Titanium (IV)-Improved H2O2/O3 Process for Acetic Acid Degradation under Acid Conditions

The effect of Ti(IV) on the degradation efficiency of acetic acid by O₃/H₂O₂ was investigated. The removal rate of acetic acid by O₃/H₂O₂ increased from 8.0% to 62.9% after 30 min when Ti(IV) was added to acetic acid solution at pH 2.8. The optimized parameters were as follows: the pH of acetic acid solution less than 5.0; the mass concentration ratios of H₂O₂ to Ti(IV), and to acetic acid about 40:1, and 3:50, respectively. The analysis of the kinetics of acetic acid degradation using the relative method showed that Ti(IV)/H₂O₂/O₃ produced more hydroxyl radicals than did H₂O₂/O₃.     

θ3 fatty acids in freshwater fish from south brazil

Lipid and fatty acid levels in the edible flesh of 17 freshwater fish from Brazil’s southern region were determined. Analyses of fatty acid methyl esters were performed by gas chromatography. Palmitic acid (C_16:0) was the predominant saturated fatty acid, accounting for 50–70% of total saturated acids. Oleic acid (C_18:1θ9) was the most abundant monounsaturated fatty acid. Linoleic acid (C_18:2θ6), linolenic acid (C_18:3θ3), and docosahexaenoic acid (C_22:6θ3) were the predominant polyunsaturated fatty acids (PUFA). The data revealed that species such as truta, barbado, and corvina were good sources of eicosapentaenoic acid (C_20:5θ3) and docosahexaenoic acid (C_22:6θ3), and that most freshwater fish examined were good sources of PUFA θ3.     

Hydrogenation of Levulinic Acid Using Formic Acid as a Hydrogen Source over Ni/SiO2 Catalysts

Several Ni/SiO₂ catalysts were developed for the hydrogenation of levulinic acid using formic acid as the hydrogen source. The catalysts were prepared by a variety of methods including impregnation, co‐precipitation, deposition‐precipitation, and citric acid assisted impregnation combustion. The morphological properties were investigated by XRD, N₂ sorption, HRTEM, and H₂ pulse chemisorption measurements. XRD patterns of the calcined material revealed the presence of NiO particles, while calcination in an inert atmosphere produced Ni particles through in situ reduction of NiO. The reaction proceeded without external H₂ flow using formic acid as hydrogen source. The Ni/SiO₂ catalyst prepared by the citric acid assisted method and calcined in inert gas flow was the most efficient for the hydrogenation of levulinic acid without external H₂ flow. The high catalytic performance was attributed to the high dispersion of cheap and earth‐abundant Ni nanoparticles and optimal porosity.     

Comparative Study of Lewis Acid Transformation on Non-reducible and Reducible Oxides Under Hydrogen Atmosphere by In Situ DRIFTS of Adsorbed NH<Subscript>3</Subscript>

The Lewis acid transformation to Bronsted acid was investigated over the Pt/γ-Al₂O₃ hybrid catalysts in the presence of hydrogen atmosphere by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed NH₃. The changes of FTIR spectra were monitored during the introduction of hydrogen at 40 °C and atmospheric pressure for 130 min. The degrees of Lewis acid transformation were varied by addition of non-reducible (SiO₂ and Al₂O₃) and reducible (ZrO₂, TiO₂ and CeO₂) oxides to the Pt/γ-Al₂O₃ catalysts as the hybrid catalysts. According to the in situ DRIFTS, the hydrogen temperature programmed reduction (H₂-TPR), and the hydrogen temperature programmed desorption (H₂-TPD) results, the introduction of hydrogen resulted in a decrease in the amount of ammonia adsorbed on Lewis acid sites, and an increase in the amount of ammonium ions on Bronsted acid sites with time on stream. It is proposed that ammonia migration from Lewis acid sites to Bronsted acid sites occurred during the introduction of hydrogen in the presence of Pt particles when compared to the observation of only observed catalysts (without Pt particles). The addition of reducible oxides led to the high rate of Lewis acid transformation, which was higher than those of the non-reducible oxides. Weaker Lewis acid sites and higher amount of hydrogen spillover over the observed catalysts enhanced the rate of Lewis acid transformation in this study. However, the amount of Lewis acid sites at the initial stage did not play an important role in these transformations.     

A DSC study of curative interactions. II. The interaction of 2,2′-dibenzothiazole with ZnO,sulfur, and stearic acid

The interaction of combinations of sulfur, 2,2′-dibenzothiazole (MBTS), ZnO, and stearic acid were studied by differential scanning calorimetry. A MBTS/stearic acid interaction was indicated as evidenced by the effect the MBTS/stearic acid combination had on the melting of sulfur, the S_α → S_β transition being suppressed in favor of a S_α → S_γ transition. The dissolution/interaction of MBTS in molten sulfur was also delayed by the MBTS/stearic acid interaction, which, it is proposed, involved protonation of the N atom in MBTS by stearic acid. MBTS did not affect the formation of zinc stearate from ZnO and stearic acid, but when sulfure was added to the mixture, the ZnO/stearic acid reaction did not go to completion. No direct evidence for the formation of 2,2′-dibenzothiazole polysulphides was found, but the absence of the S_γ → S_μ transition in sulfur/MBTS mixes was interpreted as indirect evidence of a reaction between these curatives. There was no evidence for the formation of a sulfur/MBTS/ZnO compound of the type generally attributed the role of an active sulfurating agent in accelerated sulfur vulcanization.     

Dependence of selective reduction of NO with C3H6 on acid properties of ion-exchanged zeolites

The effect of amount and strength of acid sites on the activity and selectivity for the selective reduction of NO with C₃H₆ in the presence of excess oxygen over H-form and ion-exchanged zeolites has been investigated. The activity was found to be proportional to the acid amount determined by NH₃-temperature programmed desorption, but independent of the acid strength of the zeolites. The selectivity, i.e., the ratio of the reduction of NO with C₃H₆ to the oxidation of C₃H₆ by O₂, was independent of the amount and strength of acid sites.     

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.     

Preparation of Co–Mo/B2O3/Al2O3 catalysts for hydrodesulfurization: Effect of citric acid addition

The effect of citric acid (CA) addition was studied on the HDS of thiophene over Co–Mo/(B)/Al₂O₃ catalysts. The catalysts were characterized by means of LRS, Mo K-edge EXAFS, NO adsorption capacity measurements, and UV–vis spectra. The catalysts were subjected to a chemical vapor deposition (CVD) technique using Co(CO)₃NO as a precursor of Co in order to get deeper insights into the effect of citric acid addition. It was shown that the HDS activity was enhanced by the citric acid addition up to the CA/Mo mole ratio of around 1 and leveled off with further addition. The amount of Co anchored by the CVD was increased by the addition of citric acid, suggesting an increase in the dispersion of MoS₂ particles on the catalyst by the simultaneous presence of Co, Mo and citric acid, in conformity with the increase in the NO adsorption capacity. In contrast to Co–Mo catalysts, the edge dispersion of MoS₂ particles in Mo/B/Al₂O₃ was not affected by the addition of citric acid. The LRS, UV–vis spectra and Mo K-edge EXAFS showed that Co–CA and Mo–CA surface complexes are formed by the addition of citric acid. The Co–CA surface complex is more preferentially formed on CoMo/Al than on CoMo/B/Al, in agreement with a greater promoting effect of citric acid at a lower CA/Mo mole ratio for CoMo/Al than for CoMo/B/Al.     

Regeneration von Abfallschwefelsäure

Regeneration of spent sulphuric acid . Several processes are available for the regeneration of spent sulphuric acid. Generally, the dilute acids containing at least 20% of H₂SO₄ are preconcentrated to 60 – 70% and then either further concentrated to over 90% or decomposed to SO₂. Purifying operations can be combined with these steps. Spent sulphuric acid highly contaminated with inorganic and organic compounds can frequently only be regenerated after a prior purification step, e. g. by extraction of electrolysis. Dilute spent sulphuric acid containing less than 20% of H₂SO₄ can also be regenerated, but the costs incurred by evaporation increase out of proportion with decreasing sulphuric acid concentration.     

Graft polymerization of acrylic acid onto starch using potassium permanganate acid (redox system)

Graft polymerization of acrylic acid (AA) onto rice starch using postassium permanganate/acid redox system as initiator was investigated. When starch was reacted with KMnO₄ solution, MnO₂ was deposited onto starch. The dependence of MnO₂ amount deposited was directly related to KMnO₄ concentration. Subjecting the MnO₂-containing starch to a solution consisting of monomer (AA) and acid (citric, tartaric, oxalic and hydrochloric acid) formed poly(AA)–starch graft copolymers. The graft yield, expressed as meq COOH/100 g starch, was measured by the amount of MnO₂ deposited, AA concentration, material-to-liquor ratio, kind and concentration of acid, as well as temperature and duration. Finally, the newly prepared poly(AA)–starch graft copolymers were applied to cotton textiles to determine their suitability as sizing agents. The highest graft yield was obtained with citric acid and the least with hydrochloric acid, with tartaric and oxalic acid in between. The graft yield increased by increasing the concentration of acid to a certain concentration beyond which grafting leveled off. A similar trend was observed when the magnitude of grafting was related to the amount of MnO₂ deposited. The graft yield increased by increasing the polymerization temperature from 30° to 50°C. Increasing the temperature to 60°C is accompanied by decreased grafting. On the other hand, fabric samples sized with poly(AA)–starch graft copolymers acquire higher tensile strength, elongation at break, and abrasion resistance than that sized with native rice starch, i.e., poly(AA)–starch graft copolymers serve as good sizing agents for cotton textiles. A tentative mechanism for grafting rice starch with AA using the KMnO₄/acid redox system was elucidated. © 1995 John Wiley & Sons, Inc.     

Decomposition of Carboxylic Acids in Water by O3, O3/H2O2, and O3/Catalyst

This paper studies the decomposition of formic, oxalic and maleic acids by O₃, O₃/catalyst, and O₃/H₂O₂. The catalytic effect of Co²⁺, Ni²⁺, Cu²⁺, Mn²⁺, Zn²⁺, Cr³⁺, and Fe²⁺ ions is investigated. The results showed that—Co²⁺ and Mn²⁺ have the highest catalytic activity for the decomposition of oxalic acid while the catalytic effect of the studied ions is insignificant on the rate of decomposition of formic acid. Maleic acid decomposes by ozone into formic acid and glyoxylic acid, which subsequently oxidizes to oxalic acid. Though the studied ions have no effect on the decomposition of maleic acid, they have a significant effect on the produced oxalic and glyoxylic acids. In the presence of Cu²⁺ ions glyoxylic acid is mainly transformed into formic acid and traces of oxalic acid. In such case, a complete decomposition of maleic acid and its degradation products is achieved within 45 min. The results also show that combining H₂O₂ with O₃ results in an increase in the rate of decomposition of oxalic acid. However, O₃/H₂O₂ system is less active than O₃/Co²⁺ or O₃/Mn²⁺.