Hidrogénezési reakciók rögzített komplexekkel = Hydrogenation on anchored complexes

A szteroidketonokat fémhidridekkel szokás redukálni, és ennek során a béta-epimer képződik főtermékként, és az alfa-epimer csak bonyolultabb eljárásokkal állítható elő. Ezért az volt a célunk, hogy egy egyszerű katalitikus eljárást találjunk az alfa-epimer előállítására. Azt tapasztaltuk, hogy a [RuCl2(PPh3)3] komplex alkalmazásakor mindkét epimer képződött, és így jelentős mennyiségben tudtuk előállítani az alfa-epimert is. Azt is felismertük, hogy a Ru-katalizátorok alkalmasak a szekunder alkoholok konfigurációs izomerizációjára is. Megállapítottuk, hogy az (S)-1-feniletanol racemizációja és a 17-béta-ösztradiol-3-metil-éter epimerizációja is viszonylag könnyen végbemegy a vizsgált katalizátorokon. Ez az eljárás is egy új lehetőség a más utakon csak nehezen szintetizálható szteroidalkoholok előállítására. Az N-heterociklusos karbén-komplexek nagyon érdekes fémorganikus vegyületek, mert stabilak, és sokféle átalakulást képesek katalizálni. Az általunk vizsgált [RuCl2(1-butil-3-metilimidazol-2-ilidén) (p-cimol)] komplex például kitűnően alkalmazható volt alkének, aldehidek és ketonok vizes közegű hidrogénezésére. Jó tulajdonságai miatt alkalmas prekurzornak tűnt a vizes közegű heterogenizált katalizátor előállítására is. Első ízben állítottunk elő szervetlen hordozóhoz rögzített NHC-komplexeket és alkalmaztuk ezeket a katalizátorokat C=C és C=O kettős kötéseket tartalmazó vegyületek hidrogénezésében, alkoholos és vizes közegben egyaránt. | Steroid ketones can be reduced by metal hydrides. During this reduction the beta-epimers are the main products and the alpha-epimers can be synthesized only via difficult procedures. Our goal was to develop simple catalytic procedures for the preparation of the alpha-epimers. It was found that on [RuCl2(PPh3)3] complex both epimers were produced, and the alpha-epimer Was appeared in a large quantity is this way. The Ru-catalysts are also capable for the configurational isomerization of the secondary alcohols. We found that the (S)-1-phenylethanol is racemized and the 17-beta-estradiol-3-methyl ether is epimerized easily on this catalyst. This procedure is also a new method for the preparation of steroid alcohols. The N-heterocyclic carbene complexes are very interesting organometallic compounds, because they are stable molecules and can be catalyzed different reactions. For example the [RuCl2(1-butyl-3-methylimidazol-2-ylidene) (p-cymene)] complex was very good catalysts for the hydrogenation of alkenes, aldehydes and ketones in water. Thus it seems to be a suitable precursor for the preparation of a heterogenized catalyst for the aqueous hydrogenations. We produced a first time NHC-complexes anchored an inorganic support material and used this complexes for the hydrogenation of compounds containing C=C and C=O double bonds both in alcoholic and aqueous medium

Víz. A klasszikus alternatív oldószer

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Selective modification of cytoplasmic membrane fluidity by catalytic hydrogenation provides evidence on its primary role in chilling susceptibility of the blue-green alga, Anacystis nidulans

AbstractCytoplasmic and thylakoid membranes were isolated at different stages of catalytic hydrogenation of fatty acyl double bonds in living cells of Anacystis nidulans. The reaction was limited to the lipids of cell-surface membranes during the initial period of hydrogenation, thus, we were able to produce alga cells, modified exclusively in the cytoplasmic membrane. In these unique cells, neither compositional nor physical changes were detected in the lipid phase of thylakoids. Due to the rigidification of the alkyl chains of its lipids, however, the cytoplasmic membrane became leaky and phase separated at considerably higher chilling temperatures.Since an irreversible inactivation of photosynthetic electron transport was found simultaneously, it provided direct evidence for the hypothesis that the thermotropic properties of the lipids within cytoplasmic membranes, and not those of the thylakoids, control chilling susceptibility of the blue-green alga, A.nidulans

Performance of exchange-correlation functionals on describing ground state geometries and excitations of Alizarin Red S : Effect of complexation and degree of deprotonation

Ground state optimizations and excited state calculations were performed to analyze the possible anionic forms of Alizarin Red S(ulphonated) and its ML2 type metal complexes formed with palladium(II). Six functionals have been tested (B3LYP, M06-2X, M06, BH&HLYP, PBE0, LC-wPBE, and CAM-B3LYP) with two basis sets (6-311+g(d,p) and TZVP). The relative errors of these functionals in reproducing the experimental UV-Vis absorption wavelengths are reported for the energetically lowest lying isomers. It was found that the degree of deprotonation affects several functionals in a systematic way. M06 and CAM-B3LYP xc-functionals gave the best estimates according to the average relative errors. These two functionals were then used to explore the coordination mode (hydroxy-keto or catechol) of the palladium(II) complexes and the effect of (de)protonation. © 2014 Elsevier B.V

Effect of 2-Propanol on the Transfer Hydrogenation of Aldehydes by Aqueous Sodium Formate using a Rhodium(I)-sulfonated Triphenylphosphine Catalyst

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Promoter effect of bicarbonate in hydrogenation of cinnamaldehyde catalyzed by a water-soluble Ru(II)-phosphine complex

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