2553-17-5Relevant academic research and scientific papers
UV Lamp as a Facile Ozone Source for Structural Analysis of Unsaturated Lipids Via Electrospray Ionization-Mass Spectrometry
Stinson, Craig A.,Zhang, Wenpeng,Xia, Yu
, p. 481 - 489 (2018)
Ozonolysis of alkene functional groups is a type of highly specific and effective chemical reaction, which has found increasing applications in structural analysis of unsaturated lipids via coupling with mass spectrometry (MS). In this work, we utilized a low-pressure mercury lamp (6?W) to initiate ozonolysis inside electrospray ionization (ESI) sources. By placing the lamp near a nanoESI emitter that partially transmits 185?nm ultraviolet (UV) emission from the lamp, dissolved dioxygen in the spray solution was converted into ozone, which subsequently cleaved the double bonds within fatty acyls of lipids. Solvent conditions, such as presence of water and acid solution pH, were found to be critical in optimizing ozonolysis yields. Fast (on seconds time scale) and efficient (50%–100% yield) ozonolysis was achieved for model unsaturated phospholipids and fatty acids with UV lamp-induced ozonolysis incorporated on a static and an infusion nanoESI source. The method was able to differentiate double bond location isomers and identify the geometry of the double bond based on yield. The analytical utility of UV lamp-induced ozonolysis was further demonstrated by implementation on a liquid chromatography (LC)-MS platform. Ozonolysis was effected in a flow microreactor that was made from ozone permeable tubing, so that ambient ozone produced by the lamp irradiation could diffuse into the reactor and induce online ozonolysis post-LC separation and before ESI-MS. [Figure not available: see fulltext.].
Whole-cell microtiter plate screening assay for terminal hydroxylation of fatty acids by P450s
Weissenborn, Martin J.,Notonier, Sandra,Lang, Sarah-Luise,Otte, Konrad B.,Herter, Susanne,Turner, Nicholas J.,Flitsch, Sabine L.,Hauer, Bernhard
, p. 6158 - 6161 (2016)
A readily available galactose oxidase (GOase) variant was used to develop a whole cell screening assay. This endpoint detection system was applied in a proof-of-concept approach by screening a focussed mutant library. This led to the discovery of the thus far most active P450 Marinobacter aquaeolei mutant catalysing the terminal hydroxylation of fatty acids.
Reactive Species and Reaction Pathways for the Oxidative Cleavage of 4-Octene and Oleic Acid with H2O2over Tungsten Oxide Catalysts
Yun, Danim,Ayla, E. Zeynep,Bregante, Daniel T.,Flaherty, David W.
, p. 3137 - 3152 (2021/04/06)
Oxidative cleavage of carbon-carbon double bonds (C-C) in alkenes and fatty acids produces aldehydes and acids valued as chemical intermediates. Solid tungsten oxide catalysts are low cost, nontoxic, and selective for the oxidative cleavage of C-C bonds with hydrogen peroxide (H2O2) and are, therefore, a promising option for continuous processes. Despite the relevance of these materials, the elementary steps involved and their sensitivity to the form of W sites present on surfaces have not been described. Here, we combine in situ spectroscopy and rate measurements to identify significant steps in the reaction and the reactive species present on the catalysts and examine differences between the kinetics of this reaction on isolated W atoms grafted to alumina and on those exposed on crystalline WO3 nanoparticles. Raman spectroscopy shows that W-peroxo complexes (W-(η2-O2)) formed from H2O2 react with alkenes in a kinetically relevant step to produce epoxides, which undergo hydrolysis at protic surface sites. Subsequently, the CH3CN solvent deprotonates diols to form alpha-hydroxy ketones that react to form aldehydes and water following nucleophilic attack of H2O2. Turnover rates for oxidative cleavage, determined by in situ site titrations, on WOx-Al2O3 are 75% greater than those on WO3 at standard conditions. These differences reflect the activation enthalpies (ΔH?) for the oxidative cleavage of 4-octene that are much lower than those for the isolated WOx sites (36 ± 3 and 60 ± 6 kJ·mol-1 for WOx-Al2O3 and WO3, respectively) and correlate strongly with the difference between the enthalpies of adsorption for epoxyoctane (ΔHads,epox), which resembles the transition state for epoxidation. The WOx-Al2O3 catalysts mediate oxidative cleavage of oleic acid with H2O2 following a mechanism comparable to that for the oxidative cleavage of 4-octene. The WO3 materials, however, form only the epoxide and do not cleave the C-C bond or produce aldehydes and acids. These differences reflect the distinct site requirements for these reaction pathways and indicate that acid sites required for diol formation are strongly inhibited by oleic acids and epoxides on WO3 whereas the Al2O3 support provides sites competent for this reaction and increase the yield of the oxidative cleavage products.
Synthesis of a series of hydroxycarboxylic acids as standards for oxidation of nonanoic acid
Rajabi, Mehdi,Lanfranchi, Moreno,Campo, Federica,Panza, Luigi
supporting information, p. 1149 - 1154 (2014/04/03)
The synthesis of a series of nonanoic acids hydroxylated in terminal,ω-1,ω-2,ω-3 positions is described. These compounds will be employed as useful standards for the study of enzymatic and microbiological oxidation of nonanoic acid.
Whole-cell one-pot biosynthesis of azelaic acid
Otte, Konrad B.,Kittelberger, Jens,Kirtz, Marko,Nestl, Bettina M.,Hauer, Bernhard
, p. 1003 - 1009 (2014/05/06)
Polymers benefit from the use of biogenic resources such as fatty acids. They enable easy access to valuable monomeric building blocks, which, in comparison to their exclusively fossil counterparts, lead to products with improved physicochemical properties. Monomers of special interest are medium-chain dicarboxylic acids, which are not easy to obtain by traditional chemical means. Previously, we established an in vitro pathway that combined a 9-lipoxygenase and a 9/13-hydroperoxide lyase, which enabled the conversion of linoleic acid via a hydroperoxy intermediate into 9-oxononanoic acid, the precursor of azelaic acid. Herein, we aimed for the further development of the multi-enzyme cascade, which included the oxidation of 9-oxononanoic acid and the establishment of a suitable whole-cell catalyst. A detailed investigation of the simultaneous in vitro reaction setup revealed that both lipoxygenase activation and the subsequent hydroperoxide lyase reaction depend on the hydroperoxide reaction intermediate. For the activation of lipoxygenase, the hydroperoxide lyase activity, therefore, has to be significantly reduced. In accordance with these observations, we established a suitable dual-expression system and we further demonstrated that endogenous E. coli redox enzymes are feasible to oxidize 9-oxononanoic acid to azelaic acid. The resulting whole-cell catalyst is, therefore, able to perform the direct bioconversion of linoleic acid into azelaic acid. The use of organic solvent as the second phase improved the overall performance of the E. coli host strain. The developed one-pot, single-step process afforded 29 mg L-1 of azelaic acid within 8 h with a substrate conversion of 34 % and a selectivity of 47 %. Tiny polymer factories: An E. coli whole-cell catalyst is developed for the bioconversion of linoleic acid to azelaic acid, an important building block for biopolymers. The catalytic machinery of the prokaryotic host is equipped with two plant enzymes, a lipoxygenase, and a hydroperoxide lyase. Together with an endogenous oxidoreductase, this three-enzyme cascade reaction catalyzes the oxidative cleavage of the fatty acid substrate.
Ozonolysis of methyl oleate monolayers at the air-water interface: Oxidation kinetics, reaction products and atmospheric implications
Pfrang, Christian,Sebastiani, Federica,Lucas, Claire O. M.,King, Martin D.,Hoare, Ioan D.,Chang, Debby,Campbell, Richard A.
, p. 13220 - 13228 (2014/06/24)
Ozonolysis of methyl oleate monolayers at the air-water interface results in surprisingly rapid loss of material through cleavage of the CC bond and evaporation/dissolution of reaction products. We determine using neutron reflectometry a rate coefficient of (5.7 ± 0.9) × 10-10 cm2 molecule-1 s-1 and an uptake coefficient of ～3 × 10-5 for the oxidation of a methyl ester monolayer: the atmospheric lifetime is ～10 min. We obtained direct experimental evidence that a minor change to the structure of the molecule (fatty acid vs. its methyl ester) considerably impacts on reactivity and fate of the organic film.
Fe-catalyzed one-pot oxidative cleavage of unsaturated fatty acids into aldehydes with hydrogen peroxide and sodium periodate
Spannring, Peter,Yazerski, Vital,Bruijnincx, Pieter C. A.,Weckhuysen, Bert M.,Klein Gebbink, Robertus J. M.
, p. 15012 - 15018 (2013/11/06)
A one-pot method has been developed for the oxidative cleavage of internal alkenes into aldehydes by using 0.5mol % of the nonheme iron complex [Fe(OTf)2(mix-bpbp)] (bpbp=N,N'-bis(2-picolyl)-2,2'-bipyrrolidine) as catalyst and 1.5equivalents of hydrogen peroxide and 1equivalent of sodium periodate as oxidants. A mixture of diastereomers of the chiral bpbp ligand can be used, thereby omitting the need for resolution of its optically active components. The cleavage reaction can be performed in one pot within 20h and under ambient conditions. Addition of water after the epoxidation, acidification and subsequent pH neutralization are crucial to perform the epoxidation, hydrolysis, and subsequent diol cleavage in one pot. High aldehyde yields can be obtained for the cleavage of internal aliphatic double bonds with cis and trans configuration (86-98 %) and unsaturated fatty acids and esters (69-96 %). Good aldehyde yields are obtained in reactions of trisubstituted and terminal alkenes (62-63 %). The products can be easily isolated by a simple extraction step with an organic solvent. The presented protocol involves a lower catalyst loading than conventional methods based on Ru or Os. Also, hydrogen peroxide can be used as the oxidant in this case, which is often disproportionated by second- and third-row metals. By using only mild oxidants, overoxidation of the aldehyde to the carboxylic acid is prevented. Copyright
A study into the self-cleaning surface properties - The photocatalytic decomposition of oleic acid
Rathousky, Ji?í,Kalousek, Vít,Kolá?, Michal,Jirkovsky, Jaromír,Barták, Petr
body text, p. 202 - 208 (2012/01/04)
Thin films of TiO2 exhibiting developed mesoporosity with large surface area and pores ca 10 nm in size were shown efficient photocatalyst in the decomposition of thin layers of oleic acid deposited on their surface. The pore walls of these films were composed of small anatase nanocrystals (ca 40-60%) and some amorphous phase. As major intermediates of the oleic acid decomposition, nonanal and 9-oxononanoic acid were identified. Azelaic and nonanoic acid were detected as well, representing minor intermediates. These compounds have been shown to correspond with the products of a simulated oxidative degradation of cis-3-hexenoic acid computed by means of quantum chemistry. Cis-3-hexenoic acid was chosen as a simplified model of oleic acid having similar but reduced structure. It enabled to perform the theoretical study with a reasonable consumption of computation time. The simulated oxidative degradation of cis-3-hexenoic acid was induced by an attack of hydroxyl radical on the CC double bond. The main reaction pathway led to propanal, 3-oxopropanoic acid, and also hydroxyl radical. The organic products are analogous to the main degradation intermediates of oleic acid, nonanal and 9-oxononanoic acid. The prediction of hydroxyl radical elimination in the final step of the major reaction sequence would mean that it may act as a catalyst causing accelerated degradation of unsaturated compound including fatty acids.
Process for the ozonolysis of unsaturated compounds
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Page/Page column 4, (2008/06/13)
A process for the ozonolysis of unsaturated starting materials, which is characterized in that the reaction is carried out in a structured reactor.
Method of treating dry eye disorders using 13(S)-HODE and its analogs
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Page/Page column 3, (2010/11/08)
The topical use of 13(S)-HODE and analogs are disclosed for the treatment of dry eye disorders.
