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Wyszukujesz frazę "ruthenium catalysts" wg kryterium: Temat


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Tytuł:
Synteza i zastosowanie nowych katalizatorów metatezy olefin
Synthesis and application of new olefin metathesis catalysts
Autorzy:
Hryniewicka, A.
Powiązania:
https://bibliotekanauki.pl/articles/172521.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
metateza olefin
katalizatory rutenowe
pochodne chromanu
sole imidazolidyniowe
glikokoniugaty
olefin metathesis
ruthenium catalysts
chromane derivatives
imidazolinium salts
glycoconjugates
Opis:
Olefin metathesis has emerged as a powerful tool for the formation of carboncarbon double bonds. The success of this methodology has spurred the intense investigation of new catalysts showing a better application profile. The syntheses and the application profiles of the seven new ruthenium metathesis catalysts have been described. Five of them were modified in benzylidene part with 6-hydroxychromane- and 2H-3,4-chromenemethylidene moiety. In chromanol – α-tocopherol model compound, some specific stereoelectronic effects have been observed. Introduction of this ligand to the catalyst may provide new advantageous properties. The other new catalysts contained modified N-heterocyclic carbene ligand (NHC), in which N,N’-mesityl substituents of NHC system were linked with diethylene glycol chain as a “clamping ring”. This ring would contribute to a steric shield of the NHC and ruthenium coordination center. Probably it may inforce a proper orientation of substituents in metallacyclobutane (all-cis), leading to Z-olefin formation. The obtained catalysts were investigated in model reactions: ring closing metathesis, cross metathesis and enyne metathesis. The experiments proved they efficiency. In many reactions the catalysts showed activity comparable or superior to that of commercially available Grubbs and Hoveyda 2nd generation complexes. Stereochemistry Z/E of the cross-metathesis products obtained using new and known complexes were similar as well. The catalysts were applied in the synthesis of a new type of α-tocopherol glycoconjugates. An efficient method of the synthesis Hoveyda 2nd type complexes starting from ruthenium trichloride was developed. It is possible to circumvent using special laboratory equipment and expensive reagents. Hoveyda type complexes can be achieved with very good yield in gram scale. Keywords:
Źródło:
Wiadomości Chemiczne; 2014, 68, 11-12; 961-980
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study of ruthenium-based catalysts used in homogeneous transfer hydrogenation of acetophenone
Autorzy:
Mikołajczyk, Filip
Kamiński, Kamil
Powiązania:
https://bibliotekanauki.pl/articles/185307.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ruthenium-based catalysts
transfer hydrogenation
ketones
catalysis
RuCl2(PPh3)3
katalizatory na bazie rutenu
przeniesienie uwodornienia
ketony
kataliza
RuCl2 (PPh3) 3
Opis:
A detailed comparison of catalytic properties of two different ruthenium-based catalysts in the reaction of homogeneous hydrogenation of acetophenone was performed. Additionally, methods of synthesis of both catalysts were tested and optimized in order to achieve the best possible quality and purity of the final catalysts. NMR analysis was used to analyze and identify the composition of ruthenium compounds and gas chromatography was used to analyze the conversion rate of hydrogenation reactions. It was determined that RuCl2(PPh3)3 obtained with a modified method described by Shaw’s group (Shawet al., 2007) had the best catalytic properties in the reaction performed under conditions described in Liang Wang’s publication (Wang et al., 2014). It was also determined that for concentration ratio of substrate to RuCl2(PPh3)3 amounting to 250:1 the conversion rate was much higher than that of the reaction performed with a double dose of the catalyst. Results of experiments also show that samples of the post-reaction solution should be analyzed right after the reaction, because even if they are stored in low temperature the amount of product can change up to 3–5% compared to the base sample and this change is not predictable. These findings have significant implications for further research of the reaction of homogeneous transfer hydrogenation of ketones. With the right catalysts and methods of their synthesis other parameters of this reaction can be optimized. The most important one is a change of solvent from isopropyl alcohol to a less toxic substance like water. This may increase the value of the reaction in green chemistry and chemical industry.
Źródło:
Chemical and Process Engineering; 2019, 40, 2; 213--222
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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