1779-13-1Relevant academic research and scientific papers
A highly active nanocomposite silica-carbon supported palladium catalyst for decarboxylation of free fatty acids for green diesel production: Correlation of activity and catalyst properties
Sari, Elvan,Kim, Manhoe,Salley, Steven O.,Ng, K.Y. Simon
, p. 261 - 269 (2013)
A class of Pd catalyst supported on a silica-activated carbon nanocomposite for free fatty acid (FFA) decarboxylation was developed, and displayed excellent activity and operation stability selectively for the green diesel hydrocarbons formation in the absence of H2 under mild reaction conditions. Six catalysts containing 5 wt% Pd were prepared by systematically varying the silica content in the support. In addition to the effect of particle size, the impact of catalyst preparation method on the activity and selectivity was elucidated. A 5 wt% Pd/Si-C-4 catalyst maintained stable activity for 16 days under reaction conditions of 1.5 MPa and 300°C. Although a continuous supply of H2 was not necessary, H2 treatment was essential to restore the catalytic activity and the desired product selectivity. Characterization of the catalyst revealed that the highly active Pd/Si-C-4 catalyst has easily accessible and well-distributed metallic Pd nanoparticles inside the hybrid mesopores.
Supported Ru olefin metathesis catalysts: Via a thiolate tether
Renom-Carrasco, Marc,Mania, Philipp,Sayah, Reine,Veyre, Laurent,Occhipinti, Giovanni,Gajan, David,Lesage, Anne,Jensen, Vidar R.,Thieuleux, Chloé
supporting information, p. 2886 - 2890 (2019/03/07)
Thiolate-coordinated ruthenium alkylidene complexes can give high Z-selectivity and stereoretentivity in olefin metathesis. To investigate their applicability as heterogeneous catalysts, we have successfully developed a methodology to easily immobilize prototype ruthenium alkylidenes onto hybrid mesostructured silica via a thiolate tether. In contrast, the preparation of the corresponding molecular complexes appeared very challenging in solution. These prototype supported complexes contain small thiolates but still, they are slightly more Z-selective than their molecular analogues. These results open the door to more active and selective heterogeneous catalysts by supporting more advanced thiolate Ru-complexes.
Cis-Dichloro Sulfoxide Ligated Ruthenium Metathesis Precatalysts
Johns, Adam M.,Fiamengo, Bryan A.,Herron, Jessica R.,Bourg, Jean-Baptiste,Doppiu, Angelino,Karch, Ralf,Pederson, Richard L.
supporting information, p. 218 - 222 (2019/01/14)
Novel sulfoxide-ligated ruthenium complexes were prepared by reacting second-generation metathesis precatalysts with p-toluenesulfonyl chloride in the presence of a small excess of sulfoxide. (SIMes)Ru(S-DMSO)(Ind)Cl2 (M54) and (SIMes)Ru(S-DMSO)(CHPh)Cl2 (M54a) were characterized crystallographically and, in agreement with NMR spectroscopy, were found to adopt an unusual cis-dichloro configuration. Despite having traditionally latent geometry, the new complexes were found to be highly reactive precatalysts for routine metathesis transformations. Additionally, the robustness, scalability, and industrial utility of M54 as a ruthenium synthon are demonstrated.
Fluoro-imidazopyridinylidene Ruthenium Catalysts for Cross Metathesis with Ethylene
Byun, Seunghwan,Seo, Huiyeong,Choi, Jun-Ho,Ryu, Ji Yeon,Lee, Junseong,Chung, Won-Jin,Hong, Sukwon
supporting information, p. 4121 - 4132 (2019/10/16)
A series of ruthenium metathesis catalysts bearing fluorinated imidazo[1,5-a]pyridin-3-ylidene carbenes (F-ImPy) were developed for ethenolysis (cross metathesis with ethylene) of methyl oleate. X-ray crystal structure analysis shows Ru-F interaction, and this fluorine substitution appears to be pivotal to have stable ImPy-Ru precatalysts. Ligand structure was varied for high catalyst activity and cross metathesis selectivity in ethenolysis reaction. F-ImPy-Ru catalysts showed high selectivity in ethenolysis of methyl oleate and thermal robustness under an ethylene atmosphere.
Specialized ruthenium olefin metathesis catalysts bearing bulky unsymmetrical NHC Ligands: Computations, synthesis, and application
Ma?ecki, Pawe?,Gajda, Katarzyna,Gajda, Roman,Wo?niak, Krzysztof,Trzaskowski, Bartosz,Kajetanowicz, Anna,Grela, Karol
, p. 587 - 598 (2019/01/08)
Second-generation ruthenium olefin metathesis catalysts were investigated with systematic variation of the unsymmetrical uNHC ligands. Depending on the uNHC steric bulk, the catalysts exhibited different activity and selectivity in metathesis reactions. DFT calculations and X-ray crystallographic data were used to understand the influence of uNHC ligand structure on the catalyst properties. Furthermore, the catalysts were examined in the context of reactions that are problematic for general-purpose Ru catalysts, including industrially important self-cross metathesis of α-olefins and ethenolysis of ethyl oleate.
SYNTHESIS AND CHARACTERIZATION OF METATHESIS CATALYSTS
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Paragraph 000156; 000157, (2018/03/25)
This invention relates generally to olefin metathesis catalysts, to the preparation of such compounds, compositions comprising such compounds, methods of using such compounds, and the use of such compounds in the metathesis of olefins and in the synthesis of related olefin metathesis catalysts. The invention has utility in the fields of catalysis, organic synthesis, polymer chemistry, and in industrial applications such as oil and gas, fine chemicals, and pharmaceuticals.
Stereoretentive Olefin Metathesis Made Easy: In Situ Generation of Highly Selective Ruthenium Catalysts from Commercial Starting Materials
Müller, Daniel S.,Curbet, Idriss,Raoul, Yann,Le N?tre, Jér?me,Baslé, Olivier,Mauduit, Marc
supporting information, p. 6822 - 6826 (2018/10/31)
The in situ preparation of highly stereoretentive ruthenium-based metathesis catalysts is reported. This approach completely avoids the isolation of intermediates and air-sensitive catalysts, thus allowing for the rapid access and evaluation of numerous dithiolate Ru catalysts. A procedure was established to perform cross-metathesis reactions without the use of a glovebox, and on a small scale even Schlenk techniques are not required. Consequently, the chemistry displayed in this report is available to every practicing organic chemist and presents a powerful approach for the identification of new stereoretentive catalysts.
USE OF RUTHENIUM COMPLEXES IN OLEFIN METATHESIS REACTION
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Page/Page column 19, (2018/05/27)
The invention relates to the use of ruthenium complexes, which are homogeneous catalysts and/or precatalysts of the olefin metathesis reaction, which lead to the production of alkenes containing an internal (non-terminal) double C=C bond.
Synthesis and Evaluation of Sterically Demanding Ruthenium Dithiolate Catalysts for Stereoretentive Olefin Metathesis
Montgomery, T. Patrick,Grandner, Jessica M.,Houk,Grubbs, Robert H.
, p. 3940 - 3953 (2017/10/31)
Dithiolate ligands have recently been used in ruthenium-catalyzed olefin metathesis and have provided access to a kinetically E selective pathway through stereoretentive olefin metathesis. The typical dithiolate used is relatively simple with low steric demands imparted on the catalyst. We have developed a synthetic route that allows access to sterically demanding dithiolate ligands. The catalysts generated provided a pathway to study the intricate structure-activity relationships in olefin metathesis. It was found that DFT calculations can predict the ligand arrangement around the ruthenium center with remarkable accuracy. These dithiolate catalysts proved resistant to ligand isomerization and were stable even under forcing conditions. Additionally, catalyst initiation and olefin metathesis studies delivered a better understanding to the interplay between dithiolate ligand structure and catalyst activity and selectivity.
Fast-initiating, ruthenium-based catalysts for improved activity in highly E-selective cross metathesis
Ahmed, Tonia S.,Grubbs, Robert H.
supporting information, p. 1532 - 1537 (2017/02/10)
Ruthenium-based olefin metathesis catalysts bearing dithiolate ligands have been recently employed to generate olefins with high E-selectivity (>99% E) but have been limited by low to moderate yields. In this report, 1H NMR studies reveal that a major contributing factor to this low activity is the extremely low initiation rates of these catalysts with trans olefins. Introducing a 2-isopropoxy-3-phenylbenzylidene ligand in place of the conventional 2-isopropoxybenzylidene ligand resulted in catalysts that initiate rapidly under reaction conditions. As a result, reactions were completed in significantly less time and delivered higher yields than those in previous reports while maintaining high stereoselectivity (>99% E).
