نتایج جستجو برای: brønsted acid and lewis acid catalyst

تعداد نتایج: 16951353  

2014
Thomas J. Osberger M. Christina White

A Pd(II)/bis-sulfoxide/Brønsted acid catalyzed allylic C-H oxidation reaction for the synthesis of oxazolidinones from simple N-Boc amines is reported. A range of oxazolidinones are furnished in good yields (avg 63%) and excellent diastereoselectivities (avg 15:1) to furnish products regioisomeric from those previously obtained using allylic C-H amination reactions. Mechanistic studies suggest ...

Journal: :Journal of the American Chemical Society 2011
Benjamin K Keitz Jean Bouffard Guy Bertrand Robert H Grubbs

The synthesis of a ruthenium complex containing an N-heterocylic carbene (NHC) and a mesoionic carbene (MIC) is described wherein addition of a Brønsted acid results in protonolysis of the Ru-MIC bond to generate an extremely active metathesis catalyst. Mechanistic studies implicated a rate-determining protonation step in the generation of the metathesis-active species. The activity of the NHC/...

Journal: :The Journal of chemical physics 2013
M Gruber K Hermann

We consider different reaction scenarios of the selective catalytic reduction (SCR) of NO in the presence of ammonia at perfect as well as reduced vanadium oxide surfaces modeled by V2O5(010) without and with oxygen vacancies. Geometric and energetic details as well as reaction paths are evaluated using extended cluster models together with density-functional theory. Based on earlier work of ad...

Journal: :Environmental science & technology 2011
Maraisa Gonçalves Laura Sánchez-García Erika de Oliveira Jardim Joaquín Silvestre-Albero Francisco Rodríguez-Reinoso

The effect of surface chemistry (nature and amount of oxygen groups) in the removal of ammonia was studied using a modified resin-based activated carbon. NH(3) breakthrough column experiments show that the modification of the original activated carbon with nitric acid, that is, the incorporation of oxygen surface groups, highly improves the adsorption behavior at room temperature. Apparently, t...

Journal: :Dalton transactions 2009
Craig A Wheaton Paul G Hayes Benjamin J Ireland

Interest in the utility of polylactide as a commodity polymer has increased significantly in recent years due to numerous environmental advantages over conventional petrochemically derived plastics. As such, the development of novel catalyst systems for the ring opening polymerization of lactide has seen tremendous progress in the past decade. In particular, divalent metals (i.e. Mg, Ca and Zn)...

Journal: :Physical chemistry chemical physics : PCCP 2012
Wasinee Panjan Jakkapan Sirijaraensre Chompunuch Warakulwit Piboon Pantu Jumras Limtrakul

The direct conversion of methane and carbon dioxide to acetic acid is one of the most challenging research topics. Using the density functional theory (M06-L) the study reveals the catalytic activity of the Au(I)-ZSM-5 zeolite in this reaction. The Au(I)-ZSM-5 is represented by a 34T quantum cluster model. The activation of the C-H bond over the Au-ZSM-5 zeolite would readily take place via the...

2015
Youmei Bao Naoya Kumagai Masakatsu Shibasaki

Thioamides are the preferred pronucleophiles for direct catalytic asymmetric aldol reactions in the context of soft Lewis acid/hard Brønsted base cooperative catalysis. In-depth investigation of this proton-transfer catalysis, which is virtually in equilibrium, revealed that the prominence of the retro-aldol reaction depended on the substrate combination. The retro-aldol reaction is a serious i...

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