Temat: transfer hydrogenation

Skocz do pozycji: 1.

Tytuł:: MgO Modified by X2, HX, or Alkyl Halide (X = Cl, Br, or I) Catalytic Systems and Their Activity in Chemoselective Transfer Hydrogenation of Acrolein into Allyl Alcohol
Autorzy:: Nacci, Angelo
Ulkowska, Urszula
Łomot, Dariusz
Winiarek, Piotr
Kaszkur, Zbigniew
Gliński, Marek
Współwytwórcy:: Nacci, Angelo
Wydawca:: MDPI
Cytata wydawnicza:: Gliński, M.; Ulkowska, U.; Kaszkur, Z.; Łomot, D.; Winiarek, P. MgO Modified by X 2, HX or Alkyl Halides (X = Cl, Br or I) Catalytic Systems and Their Activity in Chemoselective Transfer Hydrogenation of Acrolein into Allyl Alcohol. Molecules 2024, 29, 3180. https://doi.org/10.3390/ molecules29133180
Opis:: This research received no external funding.
A new type of catalyst containing magnesium oxide modified with various modifiers ranging from bromine and iodine, to interhalogen compounds, hydrohalogenic acids, and alkyl halides have been prepared using chemical vapor deposition (CVD) and wet impregnation methods. The obtained systems were characterized using a number of methods: determination of the concentration of X− ions, surface area determination, powder X‐ray diffraction (PXRD), surface acid–base strength measurements, TPD of probe molecules (acetonitrile, pivalonitrile, triethylamine, and n‐butylamine), TPD‐MS of reaction products of methyl iodide with MgO, and Fourier transform infrared spectroscopy (FTIR). The catalysts’ activity and chemoselectivity during transfer hydrogenation from ethanol to acrolein to allyl alcohol was measured. A significant increase in the activity of modified MgO (up to 80% conversion) in the transfer hydrogenation of acrolein was found, while maintaining high chemoselectivity (>90%) to allyl alcohol. As a general conclusion, it was shown that the modification of MgO results in the suppression of strong basic sites of the oxide, with a simultaneous appearance of Brønsted acidic sites on its surface. Independently, extensive research on the reaction progress of thirty alkyl halides with MgO was also performed in order to determine its ability to neutralize chlorinated wastes.
Dostawca treści:: Repozytorium Centrum Otwartej Nauki

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Skocz do pozycji: 2.

Tytuł:: Ionic [Ru] complex with recyclability by electro-adsorption for efficient catalytic transfer hydrogenation of aryl ketones
Autorzy:: Yue, C. J.
Xue, Q. N.
Gu, L. P.
Wang, J. F.
Tematy:: ionic Ru complex
transfer hydrogenation
electron-adsorption
catalyst recovery; Pokaż więcej
Wydawca:: Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Powiązania:: https://bibliotekanauki.pl/articles/778543.pdf Link otwiera się w nowym oknie
Opis:: The efficient reuse of homogeneous catalyst is important. Cation complex of [Ru(η⁶ -p-cymene)(PPh₃ )(CH₃ CN) Cl]PF₆ with different ligands was synthesized and characterized by infrared spectroscopy (IR), ¹ H-, ¹³ C- and ³¹ P-nuclear magnetic resonance spectroscopy (¹ H-, ¹ 3C- and ³¹ P-NMR), element analysis (EA), and high resolution mass spectrometry (HR-MS). The complex was used as a catalyst for the hydrogen transfer reduction of carbonyl for the first time, presenting an excellent catalytic performance of 89%–98% conversion of acetophenone and its derivatives. The catalyst may be efficiently reused by the electro-adsorption of 10 times to one catalyst recovery. The cation [Ru] complex presented advantages of both homogeneous and heterogeneous catalysts.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Asymetryczna redukcja ketonów z użyciem chiralnych kompleksów cynku i żelaza
Asymmetric reduction of ketones using new chiral complexes of zinc and iron
Autorzy:: Stanek, Filip
Opis:: Preparation of optically pure secondary alcohols from prochiral ketones via asymmetric reduction is an important transformation in organic synthesis for the development of biologically active molecules in the ﬁelds of pharmaceuticals, fragrance, and ﬂavor industry. The most popular methods of asymmetric reduction of prochiral ketones are hydrosilylation and transfer hydrogenation. Commonly used catalysts are based on expensive and toxic metals such as rhodium, ruthenium or iridium. This paper describes the possibility of replacing these metals by using chiral complexes containing (1R,2R)-1,2-diaminocyclohexane moiety and zinc or iron salts. Hydrosilylation catalyzed by chiral complexes of diamines with pyrophoric and expensive diethyl zinc has been developed for 15 years. Replacing diethyl zinc with readily available zinc salts makes the procedures easier and provides excellent conversions (up to >99%) and enantioselectivities (ees up to 85%). It was also carried out series reactions (hydrosilylation and transfer hydrogenation) to verify the catalytic properties of the commercially available ligands with iron and zinc salts.
Asymetryczna redukcja prochiralnych ketonów prowadzi do otrzymania czystych optycznie, drugorzędowych alkoholi znajdujących szerokie zastosowanie w przemyśle farmaceutycznym, kosmetycznym i spożywczym. Wśród wielu metod syntezy tych związków kluczowe znaczenie mają asymetryczna redukcja grupy karbonylowej na drodze transferu wodoru czy hydrosililowanie. Powszechnie stosowane katalizatory wykorzystywane w tych reakcjach bazują na drogich, trudno dostępnych i toksycznych metalach takich jak rod, ruten czy iryd. Niniejsza praca opisuje możliwość zastąpienia tych metali stosując kompleksy oparte na (1R,2R)-1,2-diaminocykloheksanie z solami cynku i żelaza. W literaturze znane są reakcje hydrosililowania z użyciem ligandów diaminowych z cynkiem, w większości przypadków stosowano jednak drogi i piroforyczny dietylocynk. W swojej pracy wykazałem, że zmiana ZnEt2 na stabilną i bezpieczną w użyciu sól Zn(OAc)2 pozwala na przeprowadzenie reakcji hydrosililowania z uzyskaniem produktu reakcji nawet z 85% nadmiarem enancjomerycznym. Wykorzystanie octanu cynku sprawia, że reakcja hydrosililowania staje się bezpieczniejsza i prostsza do wykonania w porównaniu z wcześniej stosowanymi procedurami. Przeprowadzono również szereg reakcji mających na celu sprawdzenie katalitycznych właściwości kompleksów żelaza i cynku z dostępnymi handlowo ligandami w reakcji hydrosililowania i transferu wodoru.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 4.

Tytuł:: Asymmetric transfer hydrogenation reactions catalyzed by complexes of zinc and iron
Reakcje asymetrycznego transferu wodoru katalizowane kompleksami cynku i żelaza
Autorzy:: Kozieł, Krzysztof
Opis:: W trakcie przeprowadzonych badań zbadana została aktywność katalityczna ligandów PyBOX, BOPA, IPO, DPEDA w reakcjach asymetrycznego transferu wodoru, a także asymetrycznego hydrosililowania. W reakcjach zastosowano kompleksy cynku i żelaza jako tańszą alternatywę dla związków metali szlachetnych (rutenu, rodu czy irydu). Badania wykazały, że kompleksy wymienionych ligandów nie są aktywne w reakcjach transferu wodoru, mimo udowodnionej, wysokiej aktywności w reakcjach hydrosililowania z użyciem metali takich jak cynk, żelazo, miedź czy kobalt. W badaniach sprawdzano także możliwość zastosowania katalizatora Trosta w reakcjach asymetrycznej redukcji. Testy katalityczne ujawniły wysoką aktywność tego katalizatora w reakcjach hydrosililowania. Obserwowano całkowite konwersje substratów w czasie poniżej 3 godzin, jednak enancjoselektywność reakcji była na poziomie 0-60% ee.
The studies on catalytic activity in asymmetric transfer hydrogenation (ATH) and asymmetric hydrosilylation (ASH) using PyBOX, BOPA, IPO and DPEDA ligands were performed. The reactions involved use of zinc and iron complexes as a cheaper alternative for noble metals compounds (i.e. ruthenium, rhodium or iridium). The research revealed that complexes of the mentioned ligands were inactive in asymmetric transfer hydrogenation reactions, even though they have been previously proved to be efficient catalysts in asymmetric hydrosilylation reactions based on zinc, iron, copper or cobalt compounds. Trost's catalyst was also tested for the first time as a catalyst in asymmetric hydrosilylation of ketones. Catalytic tests have shown high activity of the ProPhenol-ZnEt2 complex in hydrosilylation reactions. Full conversions of various substrates were observed usually within 3 hours, yet the stereoselectivity of these reactions was unsatisfactory.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 5.

Tytuł:: Asymetryczna redukcja ketonów z zastosowaniem kompleksów żelaza(II)
Asymmetric reduction of ketones by iron(II) complex
Autorzy:: Baran, Mateusz
Opis:: The conventional homogeneous catalysts for the asymmetric transfer hydrogenation or asymmetric hydrosilylations of ketones are based on ruthenium or rhodium complexes. The aim of this study was replacing expensive and toxic transition metals with cheap and environmentally friendly iron. Fe-catalyzed transfer hydrogenations with enantiopure protected amino acids such as D and L Boc-valine give reduction acetophenone to 1-phenylethanol. Changing of amino acid to C2¬-symmetric tridentate ligand- 2,6-Bis[(4R)-isopropyl-2-oxazolidin-2-yl)pyridine for the transfer hydrogenation give enantiomeric excess for obtaining product. The combination of chiral pybox ligands such as 2,6-bis[(4R)-isopropyl-2-oxazolidin-2-yl)pyridine, 2,6-bis[(4R)-4-phenyl-2-oxazolinyl]pyridine and O-tert-butyldiphenylsilyl-hydroxyethyl-pybox and iron salts- FeCl2, Fe(OAc)2 and Fe3(CO)12 can catalyse hydrosilylation of prochiral ketones to give the corresponding alcohols in high yields and relatively good enantiomeric excess.
Tradycyjne metody asymetrycznego transferu wodoru i asymetrycznej redukcji są katalizowane homogenicznymi katalizatorami opartymi kompleksach rutenu bądź rodu. Celem tej pracy było zastąpienie tych drogich i toksycznych metali przejściowych tańszym i mniej szkodliwym żelazem. Katalizowany żelazem transfer wodoru z enancjoczystymi zabezpieczonymi zasadami takimi jak D i L Boc-walina wykazał redukcję acetofenonu do 1-fenyloetanolu. Zastąpiony aminokwas tridentnym ligandem o symetrii C2- 2,6-bis(4’-izopropylooksazolin-2’-ylo) pirydyną w reakcji transferu wodoru wykazał nadmiar enancjomeryczny powstającego produktu. Połaczenie w reakcji hydrosililowania kompleksy chiralnego liganda pybox takiego jak 2,6-bis(4’-izopropylooksazolin-2’-ylo)pirydyna, 2,6-bis(4’-fenylooksazolin-2’-ylo)pirydyna czy O-tert-butylodifenylsililo-hydroksyetylo-pybox z solą żelaza- FeCl2, Fe(OAc)2 lub Fe3(CO)12 potrafią redukować prochiralne ketony do odpowiednich alkoholi z wysoką wydajnością i względnie dobrym nadmiarem enancjomerycznym.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 6.

Tytuł:: A study of ruthenium-based catalysts used in homogeneous transfer hydrogenation of acetophenone
Autorzy:: Mikołajczyk, Filip
Kamiński, Kamil
Tematy:: ruthenium-based catalysts
transfer hydrogenation
ketones
catalysis
RuCl2(PPh3)3
katalizatory na bazie rutenu
przeniesienie uwodornienia
ketony
kataliza
RuCl2 (PPh3) 3; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/185307.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Asymetryczne przeniesienie wodoru do ketonów katalizowane związkami Rutenu(II) i Rodu(III)
Asymmetric transfer hydrogenation of ketones catalyzed by Ruthenium(II) and Rhodium(III) complexes
Autorzy:: Karczmarska-Wódzka, A.
Kołodziejska, R.
Studzińska, R.
Wróblewski, M.
Tematy:: transfer wodoru asymetryczny
związki kompleksowe Ru(II) i Rh(III)
chiralne ligandy
prochiralne związki karbonylowe
asymmetric transfer hydrogenation
Ru(II) and Rh(III) complexes
chiral ligands
prochiral carbonyl compounds; Pokaż więcej
Wydawca:: Polskie Towarzystwo Chemiczne
Powiązania:: https://bibliotekanauki.pl/articles/172550.pdf Link otwiera się w nowym oknie
Opis:: Asymmetric hydrogen transfer (ATH) is one of the methods of stereoselective reduction of prochiral carbonyl compounds (Scheme 6). Complexes of the platinum group metals (Noyori catalysts) are the most common catalysts for AT H reactions. The specific structure of the Noyori catalyst allows to activate two hydrogen atoms. These atoms are transferred from donor to acceptor in the form of hydride ion and proton (Scheme 1). Depending on the used catalyst the transfer hydrogenation of ketons can proceed by direct and indirect transfer mechanism. The direct hydride transfer from a donor to an acceptor proceeds via a six-membered transition state (3) (Scheme 2). The indirect hydride transfer proceeds through the formation of an intermediate metal hydride. A monohydride (HLnMH) and or a dihydride (LnMH2) can be formed depending on the catalyst that is used (Scheme 3). In the monohydride route, the reduction proceeds in the inner sphere of the metal (four-membered transition state (4)) or in the outer sphere of the metal (six-membered transition state (5)) (Scheme 4). The proposed reduction of carbonyl compounds in the AT H reaction by Noyori catalysts uses the mechanism of the hydride ion and proton transfer from the donor to the catalyst and the formation of the monohydride. In the indirect transfer hydrogenation the hydride ion and proton are transferred from the monohydride to the acceptor (Scheme 5, 7). AT H reactions that lead to chiral alcohols are conducted in organic solvents or in water. Hydrogen donors most often used in organic solvent reactions are propan-2-ol or an azeotropic mixture of formic acid and triethylamine (Tab. 1, 6). Sodium formate is usually used as hydrogen donor in the reactions conducted in water. Yield and enantioselectivity of the reaction depend on many factors the most important of which are: the structure of a substrate, hydrogen donor and solvent that were used, the reaction time, substrate concentration, and the S/C ratio [2]. In the case of asymmetric reduction conducted in water the solvent pH is also of great importance [3, 7, 8]. An optimal pH range depends on the type of a catalyst [7, 8]. AT H reactions conducted in water are distinguished by a shorter reaction time and higher enantioselectivity than the reactions conducted in organic solvents. In addition, catalysts used in the AT H reactions are more stable in water allowing reuse of the catalyst without loss of its activity. This paper presented examples of the use of specific catalysts in asymmetric reactions of hydrogen transfer. In particular, I drew attention to the reactions running in the aquatic environment due to the above-mentioned advantages of this solvent. The authors focused specifically on bifunctional catalysts based on Ru(II) and Rh(III) on the account of wide usage of the catalysts of that type in AT H reactions in water and their good performance [8, 9, 15, 16, 17, 19, 20, 21, 22]. p-Cymene is the most common aromatic ligand in catalysts based on Ru(II) while in the case of catalysts with Rh(III) the most common is anionic pentamethylcyclopentadienyl ligand. In both cases the second most common ligands are diamines or amino alcohols (Scheme 8). There are better performance and enantioselectivity when diamines are used as ligands. Attempts to replace diamines and amino alcohols by Schiff bases (Scheme 13) in the catalysts containing Rh(III) proved poor results due to a very low enantioselectivity of conducted reactions (Tab. 7).
Dostawca treści:: Biblioteka Nauki

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