Nowadays, utilizing renewable resources is one of the top research interests among researchers around the world in order to maintain the synthesis of products based on chemicals. Oleic acid (C18:1) ...derived from palm oil contains the unsaturated double bond (C=C) in its long alkyl chain makes it an attractive fatty acid for the production of eco-friendly epoxide. The epoxidation of waste cooking oil was carried out by using in situ generated performic acid (HCOOOH) to produce epoxidized oleic acid. Epoxy ring-opening also known as epoxide cleavage or epoxide ring degradation occurs in the epoxidation of vegetable oils. It is imperative to minimize process losses via ring-opening in order to achieve good yields and high peroxide values of the epoxidized vegetable oil. In this study, we analysed the effect of agitation speed, the effect of molar ratio of the formic acid to waste cooking oil and the effect of hydrogen peroxide to waste cooking oil molar ratio to epoxidation waste cooking oil.
Es wird über die gezielte Synthese, die spektroskopischen Eigenschaften und die Reaktivität von Bis(trimethylphosphan)berylliumdichlorid (1) und Bisdiphenylphosphinopropanberylliumdichlorid (2), ...inklusive der Kristallstruktur von (PMe3)2BeCl2 (1) berichtet. Diese vierfach koordinierten Berylliumverbindungen können mit nButyllithium (nBuLi) zu dreifach koordiniertem (Ph2PC3H6PPh2)BenBu2 (3) und (PMe3)BenBu2 (4) alkyliert werden. PMe3 kann im Vakuum aus (PMe3)BenBu2 (4) entfernt werden, um nBu2Be2 (5) zu erhalten. Zum ersten Mal wurde die seit Dekaden postulierte Dimerisierung von nBu2Be2 in Lösung spektroskopisch beobachtet. Diese neuartige, etherfreie Syntheseroute ermöglicht den Zugang zu Berylliumdialkylen, unter völligem Ausschluss sauerstoffatomhaltiger Reagenzien und Lösungsmittel. Diese “Sauerstofffreiheit” ist entscheidend für Halbleiteranwendungen, bei denen Sauerstoff oft unerwünscht ist und um jeden Preis vermieden werden muss.
Sauerstoffbefreit: Phosphankomplexe von Berylliumchlorid wurden synthetisiert und auf ihre Eigenschaften und Reaktivität untersucht. Die Phosphanliganden agieren als entfernbare Lösungsvermittler, um Reaktionen in unpolaren, sauerstoffatomfreien Lösungsmitteln zu ermöglichen. Dies führte zu einer neuartigen Syntheseroute für Berylliumalkyle und dem ersten spektroskopischen Nachweis für die Dimerisierung von nBu2Be.
The strained olefins in trans‐cyclooctenes serve as efficient catalysts for halolactonizations, including bromolactonizations and iodolactonizations. The trans‐cyclooctene framework is essential for ...excellent catalytic performance, and the substituents also play important roles in determining efficiency. These results are the first demonstration of catalysis by a trans‐cyclooctene.
Gespannte Doppelbindungen in trans‐Cyclooctenen katalysieren Halolactonisierungen wie Brom‐ und Iodlactonisierungen. Das trans‐Cycloocten‐Motiv ist für eine leistungsfähige Katalyse unbedingt erforderlich, und auch die Substituenten nehmen Einfluss auf die Effizienz.
Relacja mówiona zarejestrowana w ramach Programu Historia Mówiona realizowanego w Ośrodku "Brama Grodzka - Teatr NN" (www.historiamowiona.teatrnn.pl). Wyraża ona wyłącznie subiektywne wspomnienia i ...poglądy świadka historii, które nie mogą być utożsamiane z oficjalnym stanowiskiem Ośrodka.
The first asymmetric cooperative Lewis base/palladium catalyzed benzylic alkylation of acyclic esters is reported. This reaction proceeds via stereodefined C1‐ammonium enolate nucleophiles. Critical ...to its success was the identification of benzylic phosphate electrophiles, which were uniquely reactive. Alkylated products were obtained with very high levels of enantioselectivity, and this method has been applied toward the synthesis of the thrombin inhibitor DX‐9065a.
Kooperative Katalyse ermöglicht die direkte enantioselektive α‐Benzylierung von Aryl‐ und Alkenylessigsäureestern mit π‐erweiterten benzylischen Elektrophilen. Für die erfolgreiche Entwicklung dieser Methode war die Verwendung von Diphenylphosphat als Nucleofug entscheidend, da dies die oxidative Addition von Palladium(0) ermöglicht.
Biogas has limited use in energy generation mainly due to the presence of hydrogen sulfide (H
2
S). Currently, most of the techniques employed in the removal of H
2
S from biogas have a chemical ...base, with high material costs and generating secondary pollutants. Biological processes for H
2
S removal have become effective and economical alternative techniques to traditional gas-treatment systems based on physicochemical techniques. Therefore, the aim of this work was to investigate the performance of a bench-scale biofilter for the removal of H
2
S present in synthetic biogas. In addition, CO
2
and CH
4
concentrations in the outlet biogas were evaluated. The inoculum used in the experiment was composed of
Acidithiobacillus thiooxidans
fixed on a packing of wood chips. Synthetic biogas was supplied to the system with a composition of 60 % CH
4
, 39 % CO
2
and 1 % H
2
S. The biofilter operated continuously for 37 days with an average H
2
S removal efficiency of 75 ± 13 % and maximum of 97 %. The elimination capacity of the system reached an average of 130 ± 23 g m
−3
h
−1
and a maximum of 169 g m
3
h
−1
. The biofiltration system showed an average reduction of only 6 % in CH
4
concentration from biogas. Thus, besides being efficient in the removal of H
2
S, the system was able to maintain the biogas energy value.
Leichter geht's mit Base: Die Bildung aminbedeckter Pd‐Nanopartikel aus Pd(acac)2 (acac=Acetylacetonat) verläuft über Pd‐Amido‐ und Pd‐Hydrid‐Zwischenstufen. Durch Zusatz einer Lewis‐Base kann die ...Reaktionstemperatur für die Synthese monodisperser Nanopartikel deutlich gesenkt werden.
The goal of work described in this paper was to better understand the methanol steam reforming (MSR) activity and selectivity patterns of ZnO and CeO2 supported Pd catalysts. This reaction is being ...used to produce H2-rich gas for a number of applications including hydrogen fuel cells. The Pd/ZnO catalysts had lower MSR rates but were more selective for the production of CO2 than the Pd/CeO2 catalysts. The CH3OH conversion rates were proportional to the H2 chemisorption uptake suggesting that the rate determining step was catalyzed by Pd. The corresponding turnover frequencies averaged 0.8+/-0.3s-1 and 0.4+/-0.2s-1 at 230 deg C for the Pd/ZnO and Pd/CeO2 catalysts, respectively. The selectivities are explained based on the reaction pathways, and characteristics of the support. The key surface intermediate appeared to be a formate. The ZnO supported catalysts had a higher density of acidic sites and favored pathways where the intermediate was converted to CO2 while the CeO2 supported catalysts had a higher density of basic sites and favored the production of CO.
Three kinds of superhydrophobic polyimide (PI) nanotube arrays with controllable sliding angles were prepared by controlling the solvent evaporation and drying process.
In this paper, we report the ...fabrication of superhydrophobic polyimide (PI) nanotube arrays with different topographies, which possess slippery or “sticky” superhydrophobicity. The PI nanotube arrays were fabricated by the porous alumina membrane molding method. We regulated three kinds of solvent evaporation and drying processes, which controlled different congregated and noncongregated topographies of PI nanotube arrays. Large scale comb-like congregated topography possesses a small sliding angle (SA
<
5°) , small scale comb-like congregated topography possesses a medium sliding angle (SA is about 30°), noncongregated topography possesses a large sliding angle (strong adhesive force to water droplet). Moreover, the as-prepared superhydrophobic PI nanotube arrays have remarkable resistivity to acid, weak base, high temperature (up to 350
°C) and various organic solvents. Our work provides a facile and promising strategy to fabricate superhydrophobic surfaces with controlled sliding angles by utilizing self-organization effect, and such high performance superhydrophobic PI nanotube arrays can be used as coating materials in various harsh conditions.
A facile, efficient, and highly diastereo‐ and enantioselective bromoetherification of diolefinic diols has been developed using an amino‐thiocarbamate catalyst. Further manipulations of the ...bromoether products enabled entry into a new class of spirocycles which are distinctively lacking in the literature.
Weg mit der Symmetrie! Eine effiziente, hoch diastereo‐ und enantioselektive Bromveretherung von Diolefindiolen nutzt einen Aminothiocarbamat‐Katalysator. Folgereaktionen der resultierenden Bromether öffnen einen Zugang zu einer neuen Klasse von Spirocyclen mit drei quartären Kohlenstoffstereozentren.
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