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1

Asymetryczne reakcje pericykliczne katalizowane kompleksami magnezu

Czombik Anna

Wiadomości Chemiczne

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2022

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[Z] 76, 9-10

755--788

EN

II Group-metals, like magnesium, are one of the most widespread elements in the environment. The abundance of II-group metals in the Earth’s crust is over 108 times greater than the precious metals. For the industrial applications, the important factors are the low costs of production and higher accessibility of their compounds. This puts the spotlight on alkaline-earth metals competing with transition elements as catalysts in organic synthesis. Features of their derivatives, like mild Lewis acidity and strong Brønsted basicity enabled them to catalyze reactions where Lewis-acidactivation of the substrate is essential. In this review the emphasis was put on magnesium-catalyzed pericyclic reactions, which are recognized as one of the most important methods of new carbon-carbon or carbon-heteroatom bonds formation. Using the catalysts based on II-group metal cations and chiral ligands, a highly stereoselective conversion of achiral substrates into enantioenriched products is possible. The Mg-based catalysts have been used in Diels-Alder, ene and 1,3-dipolar additions. Described synthesis methods were characterized by high efficiency (chemical yields and enantiomeric excesses). Where applicable, the relationships between the structure of catalyst/substrates, conditions and efficiency were discussed. Just now there are a few applications, for example in synthesis of alkaloid (–)-manzacidine or antibiotic of algal origin – (–)-malyngolide.

2

Characterization of zirconia-magnesia-yttria materials used as catalysts for esters and alcohols fractions transformations by ketonization

Klimkiewicz R., Teterycz H., Sikora E., Rakoczy J., Biskupski A., Trawczyński J.

Polish Journal of Chemical Technology

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2005

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Vol. 7, nr 1

29-32

EN

In former publications the application of the monophase material Zr(0.89)-Mg(0.10)-Y(0.01)-O as a catalyst of the waste alcohol and ester fractions ketonization was described. In the present work various compositions of the Zr-Mg-Y-O type respecting the reaction group: Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL) synthesized from chlorides, Zr-Mg-Y-O(SULPH) from zirconium sulfate, mixed oxide ZrO2+Y2O(3BOG) and its derivative Zr-Mg-Y-O(BOG) are characterized. The catalytic properties of the materials were characterized with the use of n-butanol test, isopropanol test, cyclohexene + H2 test as well as TPD NH3, and FT-IR (pyridine) spectroscopy. Zr-Mg-Y-O(SULPH) catalyst obtained from the sulfate precursor, as compared to Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL), revealed a much lower selectivity of the reaction of the primary and secondary alcohols into ketones. The surfaces of Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL) and ZrO2 + Y2O(3BOG) materials, although they contained comparable numbers of the Lewis acidic centers (164 and 126 žmol Py/g, respectively), differed considerably as for the selectivity in the reaction of n-butyl alcohol condensation: ZrO2,+Y2O(3BOG) was not a selective catalyst of the ketonization. Under the conditions of the cyclohexene + H2 test over ZrO2 + Y2O(3BOG) the reaction proceeded towards isomerization and cracking, while Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL) catalyzed hydrogenation. The application of Zr-Mg-Y-O(BOG) material of the lower Lewis acidity (62 žmol Py/g) did not result in the higher selectivity of the ketonization. However, the result of the cyclohexene + H2 test changed. Thus, a considerable number of the Lewis acidic centers (such as ZrO2+Y2O(3BOG) was not the only necessary condition for the bimolecular condensation of the primary alcohols and/or aldehydes or for esters transformation. The search for materials should be conducted towards the syntheses of the catalysts of the dehydrogenation properties and containing in their structure oxygen vacancies which could form the Lewis acidic centers.

3

Effects of Lewis acids on the resultant properties of char and coal tar after carbonisation

Plevova E.

Karbo

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2003

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Nr 2

82-84

EN

The controlled impregnation with highly concentrated solutions causing increase of specific surface were mentioned in literature [ 1,3]. This work was aranged at a bit different way because of several reasons. The conditions were modelated due to occurrence of coking coals with higher contents of some metals at Ostrava-Karvina Coal Basin (OKCB) and Slany basin. These kinds of coal are important component of coal blends and they are coked at coking chambers. Metal admixtures at coal influence properties of obtained liquid and solid phase, evocate e.g. local destruction of silica masonry, and it is a really relevant problem to eliminate these admixtures during coal preparation. Also the process of chemical agent washing induces water sources pollution, where technologies of water purity treatment are economically consumptive, and it also brings problems with environmental protection. After coal preparation, low concentration of residual metals still exists, therefore the low concentration of impregnation agents was chosen. Series of impregnated carbons were prepared from bituminous coal by chemical activation with different chloride solutions. The resultant sorption properties of obtained activated carbons were estimated. Activated carbons with best sorption properties were further investigated as well as obtained coal tar. Their properties were evaluated as raw material for carbon industry. Impregnation by ZnCl2, PbCl2 and A1C13 gives activated chars with the highest sorption capacity in comparison to other used chloride solutions.

PL

Przedstawiono rezultaty badań węgla bitumicznego impregnowanego -chemicznie aktywowanego różnymi roztworami chlorków. Oceniono wybrane wlaściwości sorpcyjne otrzymanych karbonizatów - węgli aktywnych. Badaniom poddano również otrzymane ciekłe produkty -smołę węglową. Właściwości otrzymanych węgli aktywnych zostały oszacowane pod kątem wymagań przemysłu tworzyw węglowych. Wykazano, że impregnacja ZnCl2, PbCl2 i AlCl3 daje węgle aktywne o wyższej pojemności sorpcyjnej w porównaniu z innymi zastosowanymi roztworami chlorków.