591-47-9Relevant academic research and scientific papers
Influence of Intracrystalline Ionic Strength in MFI Zeolites on Aqueous Phase Dehydration of Methylcyclohexanols
Milakovi?, Lara,Hintermeier, Peter H.,Liu, Yue,Baráth, Eszter,Lercher, Johannes A.
, p. 24806 - 24810 (2021)
The impact of the concentration of hydrated hydronium ions and in turn of the local ionic strength in MFI zeolites has been investigated for the aqueous phase dehydration of 4-methylcyclohexanol (E1 mechanism) and cis-2-methylcyclohexanol (E2 mechanism). The E2 pathway with the latter alcohol led to a 2.5-fold higher activity. The catalytic activity normalized to the hydronium ions (turnover frequency, TOF) passed through a pronounced maximum, which is attributed to the increasing excess chemical potential of the alcohols in the pores, increasing in parallel with the ionic strength and the additional work caused by repulsive interactions and charge separation induced by the bulky alcohols. While the maximum in rate observed is invariant with the mechanism or substitution, the reaction pathway is influencing the activation parameters differently.
Well-defined dendrimer encapsulated ruthenium SCILL catalysts for partial hydrogenation of toluene in liquid-phase
Antonels, Nathan Charles,Benjamin Williams, Marc,Meijboom, Reinout,Haumann, Marco
, p. 156 - 160 (2016)
Dendrimer encapsulated ruthenium nanoparticles (RuDEN) were prepared and immobilized on silica 60 and silica 100. The size of the supported RuDENs was investigated using HRTEM and the generation six G6-RuDEN was found to be the most stable RuDEN upon immobilization. The catalysts were evaluated in the liquid-phase hydrogenation of toluene at a hydrogen pressure of 30 bar and 110 °C. Several ionic liquids were used as coatings for the G5-RuSil100 catalysts to give various Solid Catalysts with Ionic Liquid Layer (SCILL). In each case the selectivity towards methylcyclohexenes was increased compared to the uncoated catalyst, accompanied by an expected decrease in activity with the highest methylcyclohexene selectivity being observed when using [EMIM][NTf2] as a coating.
Rearrangement of r-5-methyl-c-2-(trimethylsilyl)cyclohexan-t-yl 2,4-dinitrobenzoate in Chloroform
Green, Alison J.,Kuan, Yew Leong,White, Jonathan M.
, p. 2023 - 2024 (1994)
Isomerisation of the title compound 3 to the ester 4 in deuteriochloroform is believed to occur via rearrangement of an intermediate β-trimethylsilyl substituted carbocation, with subsequent capture by the 2,4-dinitrobenzoate anion.
Depolymerization and hydrodeoxygenation of lignin to aromatic hydrocarbons with a Ru catalyst on a variety of Nb-based supports
Ma, Di,Lu, Shenglu,Liu, Xiaohui,Guo, Yong,Wang, Yanqin
, p. 609 - 617 (2019/04/03)
Efficient conversion of lignin to aromatic hydrocarbons via depolymerization and subsequent hydrodeoxygenation is important. Previously, we found that NbOx species played a key role in the activation and cleavage of C–O bonds in lignin and its model compounds. In this study, commercial niobic acid (HY-340), niobium phosphate (NbPO-CBMM) and lab-made layered niobium oxide (Nb2O5-Layer) were chosen as supports to study the effect of Br?nsted and Lewis acids on the activation of C–O bonds in lignin conversion. A variety of Ru-loaded, Nb-based catalysts with different Ru particle sizes were prepared and applied to the conversion of p-cresol. The results show that all the Ru/Nb-based catalysts produce high mole yields of C7–C9 hydrocarbons (82.3–99.1%). What's more, Ru/Nb2O5-Layer affords the best mole yield of C7–C9 hydrocarbons and selectivity for C7–C9 aromatic hydrocarbons, of up to 99.1% and 88.0%, respectively. Moreover, it was found that Lewis acid sites play important roles in the depolymerization of enzymatic lignin into phenolic monomers and the cleavage of the C–O bond of phenols. Additionally, the electronic state and particle size of Ru are significant factors which influence the selectivity for aromatic hydrocarbons. A partial positive charge on the metallic Ru surface and a smaller Ru particle size are beneficial in improving the selectivity for aromatic hydrocarbons.
PROCESS FOR PHOTOCATALYTIC ACCEPTOR-FREE DEHYDROGENATION OF ALKANES AND ALCOHOLS
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Paragraph 0065, (2015/09/23)
A process for photocatalytic acceptor-free dehydrogenation of alkanes and alcohols, in which an alkane or an alcohol is irradiated in the presence of a rhodium complex containing organic phosphorus(III) compounds as ligands as a catalyst, and in the presence of at least one Lewis base is provided.
Towards a practical development of light-driven acceptorless alkane dehydrogenation
Chowdhury, Abhishek Dutta,Weding, Nico,Julis, Jennifer,Franke, Robert,Jackstell, Ralf,Beller, Matthias
supporting information, p. 6477 - 6481 (2014/06/24)
The efficient catalytic dehydrogenation of alkanes to olefins is one of the most investigated reactions in organic synthesis. In the coming years, an increased supply of shorter-chain alkanes from natural and shale gas will offer new opportunities for inexpensive carbon feedstock through such dehydrogenation processes. Existing methods for alkane dehydrogenation using heterogeneous catalysts require harsh reaction conditions and have a lack of selectivity, whereas homogeneous catalysis methods result in significant waste generation. A strong need exists for atom-efficient alkane dehydrogenations on a useful scale. Herein, we have developed improved acceptorless catalytic systems under optimal light transmittance conditions using trans-[Rh(PMe3) 2(CO)Cl] as the catalyst with different additives. Unprecedented catalyst turnover numbers are obtained for the dehydrogenation of cyclic and linear (from C4) alkanes and liquid organic hydrogen carriers. These reactions proceed with unique conversion, thereby providing a basis for practical alkane dehydrogenations.
Enantioselective synthesis of chiral sulfones by ir-catalyzed asymmetric hydrogenation: A facile approach to the preparation of chiral allylic and homoallylic compounds
Zhou, Taigang,Peters, Byron,Maldonado, Matias F.,Govender, Thavendran,Andersson, Pher G.
, p. 13592 - 13595 (2012/10/08)
A highly efficient and enantioselective Ir-catalyzed hydrogenation of unsaturated sulfones was developed. Chiral cyclic and acyclic sulfones were produced in excellent enantioselectivities (up to 98% ee). Coupled with the Ramberg-Baecklund rearrangement, this reaction offers a novel route to chiral allylic and homoallylic compounds in excellent enantioselectivities (up to 97% ee) and high yields (up to 94%).
{(1 R,2 R,4 R)-4-Methyl-1,2-cyclohexanediamine}oxalatoplatinum(II): A Novel Enantiomerically Pure Oxaliplatin Derivative Showing Improved Anticancer Activity in Vivo
Abramkin, Sergey A.,Jungwirth, Ute,Valiahdi, Seied M.,Dworak, Claudia,Habala, Ladislav,Meelich, Kristof,Berger, Walter,Jakupec, Michael A.,Hartinger, Christian G.,Nazarov, Alexey A.,Galanski, Markus,Keppler, Bernhard K.
supporting information; experimental part, p. 7356 - 7364 (2011/01/12)
Novel derivatives of the clinically established anticancer drug oxaliplatin were synthesized. Cytotoxicity of the compounds was studied in six human cancer cell lines by means of the MTT assay. Additionally, most promising complexes were also investigated in cisplatin- and oxaliplatin-resistant human cancer cell models. The therapeutic efficacy in vivo was studied in the murine L1210 leukemia model. Most remarkably, {(1R,2R,4R)-4-methyl-1,2-cyclohexanediamine} oxalatoplatinum(II), comprising an equatorial methyl substituent at position 4 of the cyclohexane ring, was as potent as oxaliplatin in vitro but distinctly more effective in the L1210 model in vivo at the optimal dose. The advantage observed in the in vivo situation was mainly based on a more favorable therapeutic index. The maximum tolerated dose of the novel analogue was higher than that of oxaliplatin and caused a greater increase in life span (>200% versus 152%), with more animals experiencing long-term survival (5/6 versus 2/6). These data support further (pre)clinical development of the methyl-substituted oxaliplatin analogue with improved anticancer activity.
Low-valent titanium-mediated stereoselective alkylation of allylic alcohols
Lysenko, Ivan L.,Kim, Keunho,Hyung, Goo Lee,Jin, Kun Cha
supporting information; scheme or table, p. 15997 - 16002 (2009/05/15)
We have developed low-valent titanium-mediated 1,3-transpositive cross-coupling reactions of acyclic and cyclic allylic alcohols for the stereoselective introduction of ethyl, 2-silylethyl, 2-phenethyl, and alkenyl groups. Cross-coupling of an allylic alcohol with a vinylsilane or styrene derivative is particularly noteworthy, as an efficient cross-selective coupling of two alkenes has been elusive. The stereochemistry of the cross-coupling alkylation is consistent with syn addition/β-elimination.
Silica-supported dendrimer-palladium complex-catalyzed selective hydrogenation of dienes to monoolefins
Zweni, Pumza P.,Alper, Howard
, p. 725 - 731 (2007/10/03)
The selective hydrogenation of cyclic and acyclic dienes to monoolefins occurs under very mild conditions, in the presence of silica-supported PAMAM-Pd complexes. The activity and selectivity of this reaction is sensitive to the dendrimer structure. These dendritic complexes display excellent recycle properties, retaining activity for up to eight recycles.
