Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid
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Zn-Al Mixed Oxides Decorated with Potassium As Catalysts for HT-WGS: Preparation and Properties
catalysts Article Zn-Al Mixed Oxides Decorated with Potassium as Catalysts for HT-WGS: Preparation and Properties Katarzyna Antoniak-Jurak * , Paweł Kowalik, Kamila Michalska, Wiesław Próchniak and Robert Bicki Łukasiewicz Research Network—New Chemical Syntheses Institute, Al. Tysi ˛acleciaPa´nstwa Polskiego 13A, 24-110 Puławy, Poland; [email protected] (P.K.); [email protected] (K.M.); [email protected] (W.P.); [email protected] (R.B.) * Correspondence: [email protected]; Tel.: +48-8-1473-1754 Received: 8 September 2020; Accepted: 18 September 2020; Published: 21 September 2020 Abstract: A set of ex-ZnAl-LDHs catalysts with a molar ratio of Zn/Al in the range of 0.3–1.0 was prepared using co-precipitation and thermal treatment. The samples were characterized using various methods, including X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy FT-IR, N2 adsorption, Temperature-programmed desorption of CO2 (TPD-CO2) as well as Scanning electron microscopy (SEM-EDS). Catalyst activity and long-term stability measurements were carried out in a high-temperature water–gas shift (HT-WGS) reaction. Mixed oxide catalysts with various Zn/Al molar ratios decorated with potassium showed high activity in the HT-WGS reaction within the temperature range of 330–400 ◦C. The highest activity was found for the Zn/Al molar ratio of 0.5 corresponding to spinel stoichiometry. However, the catalyst with a stoichiometric spinel molar ratio of Zn/Al (ZnAl_0.5_K) revealed a higher tendency for surface migration and/or vaporization of potassium during overheating at 450 ◦C. -
Opportunities for Catalysis in the 21St Century
Opportunities for Catalysis in The 21st Century A Report from the Basic Energy Sciences Advisory Committee BASIC ENERGY SCIENCES ADVISORY COMMITTEE SUBPANEL WORKSHOP REPORT Opportunities for Catalysis in the 21st Century May 14-16, 2002 Workshop Chair Professor J. M. White University of Texas Writing Group Chair Professor John Bercaw California Institute of Technology This page is intentionally left blank. Contents Executive Summary........................................................................................... v A Grand Challenge....................................................................................................... v The Present Opportunity .............................................................................................. v The Importance of Catalysis Science to DOE.............................................................. vi A Recommendation for Increased Federal Investment in Catalysis Research............. vi I. Introduction................................................................................................ 1 A. Background, Structure, and Organization of the Workshop .................................. 1 B. Recent Advances in Experimental and Theoretical Methods ................................ 1 C. The Grand Challenge ............................................................................................. 2 D. Enabling Approaches for Progress in Catalysis ..................................................... 3 E. Consensus Observations and Recommendations.................................................. -
Bifunctional Molecular Catalysts with Cooperating Amine/Amido Ligands
No.147 No.147 Bifunctional Molecular Catalysts with Cooperating Amine/Amido Ligands Yoshihito Kayaki and Takao Ikariya* Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo, 152-8552, Japan E-mail: [email protected] 1. Introduction and a coordinatively saturated hydrido(amine)ruthenium complex are involved in the catalytic cycle as depicted in The chemistry of transition metal-based molecular Figure 1. The amido complex has sufficient Brønsted basicity catalysts has progressed with discoveries of novel catalytic to dehydrogenate readily secondary alcohols including transformations as well as understanding the reaction 2-propanol to produce the hydrido(amine) complex. The NH mechanisms. Particularly, significant efforts have been unit bound to the metal center in the amine complex exhibits continuously paid to develop bifunctional molecular catalysts a sufficiently acidic character to activate ketonic substrates. having the combination of two or more active sites working in During the interconversion between the amido and the amine concert, to attain highly efficient molecular transformation for complexes, the metal/NH moiety cooperatively assists the organic synthesis. We have recently developed metal–ligand hydrogen delivery via a cyclic transition state where H– and cooperating bifunctional catalysts (concerto catalysts), in which H+ equivalents are transferred in a concerted manner from the the non-innocent ligands directly participate in the substrate hydrido(amine) complex to the C=O linkage or from 2-propanol activation and the bond formation. The concept of bifunctional to the amido complex without direct coordination to the metal molecular catalysis is now an attractive and general strategy to center (outer-sphere mechanism). -
Organocatalytic Asymmetric N-Sulfonyl Amide C-N Bond Activation to Access Axially Chiral Biaryl Amino Acids
ARTICLE https://doi.org/10.1038/s41467-020-14799-8 OPEN Organocatalytic asymmetric N-sulfonyl amide C-N bond activation to access axially chiral biaryl amino acids Guanjie Wang1, Qianqian Shi2, Wanyao Hu1, Tao Chen1, Yingying Guo1, Zhouli Hu1, Minghua Gong1, ✉ ✉ ✉ Jingcheng Guo1, Donghui Wei 2 , Zhenqian Fu 1,3 & Wei Huang1,3 1234567890():,; Amides are among the most fundamental functional groups and essential structural units, widely used in chemistry, biochemistry and material science. Amide synthesis and trans- formations is a topic of continuous interest in organic chemistry. However, direct catalytic asymmetric activation of amide C-N bonds still remains a long-standing challenge due to high stability of amide linkages. Herein, we describe an organocatalytic asymmetric amide C-N bonds cleavage of N-sulfonyl biaryl lactams under mild conditions, developing a general and practical method for atroposelective construction of axially chiral biaryl amino acids. A structurally diverse set of axially chiral biaryl amino acids are obtained in high yields with excellent enantioselectivities. Moreover, a variety of axially chiral unsymmetrical biaryl organocatalysts are efficiently constructed from the resulting axially chiral biaryl amino acids by our present strategy, and show competitive outcomes in asymmetric reactions. 1 Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China. 2 College -
2-Alkenes from 1-Alkenes Using Bifunctional Ruthenium Catalysts
Article Cite This: Org. Process Res. Dev. 2018, 22, 1672−1682 pubs.acs.org/OPRD Catalyst versus Substrate Control of Forming (E)‑2-Alkenes from 1‑Alkenes Using Bifunctional Ruthenium Catalysts Erik R. Paulson, Esteban Delgado, III, Andrew L. Cooksy, and Douglas B. Grotjahn* San Diego State University, 5500 Campanile Drive, San Diego, California 92182-1030, United States *S Supporting Information ABSTRACT: Here we examine in detail two catalysts for their ability to selectively convert 1-alkenes to (E)-2-alkenes while κ2 + limiting overisomerization to 3- or 4-alkenes. Catalysts 1 and 3 are composed of the cations CpRu( -PN)(CH3CN) and * κ2 + − Cp Ru( -PN) , respectively (where PN is a bifunctional phosphine ligand), and the anion PF6 . Kinetic modeling of the fi reactions of six substrates with 1 and 3 generated rst- and second-order rate constants k1 and k2 (and k3 when applicable) that represent the rates of reaction for conversion of 1-alkene to (E)-2-alkene (k1), (E)-2-alkene to (E)-3-alkene (k2), and so on. The k1:k2 ratios were calculated to produce a measure of selectivity for each catalyst toward monoisomerization with each substrate. fi The k1:k2 values for 1 with the six substrates range from 32 to 132. The k1:k2 values for 3 are signi cantly more substrate- dependent, ranging from 192 to 62 000 for all of the substrates except 5-hexen-2-one, for which the k1:k2 value was only 4.7. Comparison of the ratios for 1 and 3 for each substrate shows a 6−12-fold greater selectivity using 3 on the three linear substrates as well as a >230-fold increase for 5-methylhex-1-ene and a 44-fold increase for a silyl-protected 4-penten-1-ol substrate, which are branched three and five atoms away from the alkene, respectively. -
'New Insights on the Selective Oxidation of Methanol to Formaldehyde on Femo Based Catalysts'
‘New Insights on the Selective Oxidation of Methanol to Formaldehyde on FeMo Based Catalysts' Catherine Brookes School of Chemistry Cardiff University Thesis for the degree of Doctor of Philosophy i This thesis was submitted for examination in August 2015. ii Abstract The selective oxidation of methanol has been studied in detail, with particular focus on gaining insights into the surface active sights responsible for directing the selectivity to formaldehyde. Various Fe and Mo containing oxides have been investigated for their reactivity with methanol, to gain an understanding of the different roles of these components in the industrial catalyst employed, which is a mixed phase comprised of MoO 3 and Fe 2(MoO 4)3. Catalysts have primarily been tested through using TPD (temperature programmed desorption) and TPPFR (temperature programmed pulsed flow reaction). The reactivity of Fe 2O3 is dominated by combustion products, with CO 2 and H 2 produced via a formate intermediate adsorbing at the catalyst surface. For MoO 3 however, the surface is populated by methoxy intermediates, so that the selectivity is almost 100 % directed to formaldehyde. When a mixture of isolated Fe and Mo sites co-exist, the surface methoxy becomes stabilised, resulting in a dehydrogenation reaction to CO and H 2. CO and CO 2 can also be observed on Mo rich surfaces, however here a consequence of the further oxidation of formaldehyde, through a linear pathway. TPD and DRIFTS identify these intermediates and products forming. Since the structure of the industrial catalyst is relatively complex, in that it contains both MoO 3 and Fe 2(MoO 4)3, it is difficult to identify the active site for the reaction with methanol. -
Chiral Bifunctional Phosphine Ligand Enabling Gold-Catalyzed
Communication Cite This: J. Am. Chem. Soc. 2019, 141, 3787−3791 pubs.acs.org/JACS Chiral Bifunctional Phosphine Ligand Enabling Gold-Catalyzed Asymmetric Isomerization of Alkyne to Allene and Asymmetric Synthesis of 2,5-Dihydrofuran Xinpeng Cheng, Zhixun Wang, Carlos D. Quintanilla, and Liming Zhang* Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States *S Supporting Information Scheme 1. Soft Propargylic Deprotonation and Chiral 2,5- ABSTRACT: The asymmetric isomerization of alkyne to Dihydrofuran Synthesis allene is the most efficient and the completely atom- economic approach to this class of versatile axial chiral structure. However, the state-of-the-art is limited to tert- butyl alk-3-ynoate substrates that possess requisite acidic propargylic C−H bonds. Reported here is a strategy based on gold catalysis that is enabled by a designed chiral bifunctional biphenyl-2-ylphosphine ligand. It permits isomerization of alkynes with nonacidic α-C−H bonds and hence offers a much-needed general solution. With chiral propargylic alcohols as substrates, 2,5-disubstituted 2,5-dihydrofurans are formed in one step in typically good yields and with good to excellent diastereoselectivities. With achiral substrates, 2,5-dihydrofurans are formed with good to excellent enantiomeric excesses. A novel center- chirality approach is developed to achieve a stereocontrol effect similar to an axial chirality in the designed chiral ligand. The mechanistic studies established that the precatalyst axial epimers are all converted into the catalytically active cationic gold catalyst owing to the fluxional axis of the latter. from https://pubs.acs.org/doi/10.1021/jacs.8b12833. -
Relationship Between Chemical Structure and the Occupational
243 Occup Environ Med: first published as 10.1136/oem.2004.016402 on 18 March 2005. Downloaded from ORIGINAL ARTICLE Relationship between chemical structure and the occupational asthma hazard of low molecular weight organic compounds J Jarvis, M J Seed, R A Elton, L Sawyer, R M Agius ............................................................................................................................... Occup Environ Med 2005;62:243–250. doi: 10.1136/oem.2004.016402 Aims: To investigate quantitatively, relationships between chemical structure and reported occupational asthma hazard for low molecular weight (LMW) organic compounds; to develop and validate a model linking asthma hazard with chemical substructure; and to generate mechanistic hypotheses that might explain the relationships. Methods: A learning dataset used 78 LMW chemical asthmagens reported in the literature before 1995, and 301 control compounds with recognised occupational exposures and hazards other than respiratory sensitisation. The chemical structures of the asthmagens and control compounds were characterised by the presence of chemical substructure fragments. Odds ratios were calculated for these fragments to determine which were associated with a likelihood of being reported as an occupational asthmagen. Logistic See end of article for regression modelling was used to identify the independent contribution of these substructures. A post-1995 authors’ affiliations set of 21 asthmagens and 77 controls were selected to externally validate the model. ...................... -
Platinum Metals Industrial Catalysts Catalysis of Organic Reactions EDITED by M
Platinum Metals Industrial Catalysts Catalysis of Organic Reactions EDITED BY M. G. SCAROS AND M. L. PRUNIER, Marcel Dekker, New York, 1995, 599 pages, ISBN 0-8247-9364-1, U.S. $195.00 This book comprises a set of papers presented reactant purity, agitation and poisons are at the 15th Conference on Catalysis of Organic considered. This is followed by a paper detail- Reactions, held in Phoenix, Arizona, in May ing noble metal recovery operations and the var- 1994. It covers a variety of topics, such as het- ious steps involved in the noble metal “loop”. erogeneous catalysis, asymmetric hydrogena- Heterogeneous catalysis in organic synthesis tion, hydrogenation, oxidation, hydroformyla- is discussed by R. L. Augustine and colleagues tion, catalyst design and catalyst characterisation. from Seton Hall University, New Jersey. This One topic which is emphasised is hydrogena- is illustrated by the platinum catalysed oxida- tion (alpha to omega), and this is intended to tion of alcohols, carbon-carbon bond forming allow a better understanding of the entire reactions of supported palladium catalysts for process, from choosing a catalyst to the noble the Heck type arylation of allylic groups, and metal “loop”. There are over 60 papers and 186 by enantioselective heterogeneous catalysis, contributors, with a healthy number of these which includes the hydrogenation of a-ketoesters being from industry. A large proportion of the to chiral a-hydroxyesters using chinchona alka- papers deal with reactions involving platinum loid modified platinum catalysts. group metal catalysts, reflecting their impor- A detailed study of the homogeneously pal- tance to both academia and industry. -
Design of Bifunctional Tetraarylphosphonium Salt Catalysts
TCIMAIL No. 183 l Spring 2020 Spring 2020 l No. 183 TCIMAIL Research Article Design of Bifunctional Tetraarylphosphonium Salt Catalysts Yasunori Toda and Hiroyuki Suga Department of Materials Chemistry, Faculty of Engineering, Shinshu University: Wakasato, Nagano-shi, Nagano 380-8553, Japan E-mail: [email protected]; [email protected] Abstract: The [3+2] reactions between epoxides and carbon dioxide proceeded effectively in the presence of bifunctional tetraarylphosphonium salt catalysts, affording the corresponding cyclic carbonates in high yields. The use of isocyanates instead of carbon dioxide was found to be efficient for the synthesis of oxazolidinones from epoxides. In addition, we have successfully developed a novel phosphonium ylide as a nucleophilic catalyst for selective acylation of primary alcohols. Keywords: organocatalyst, bifunctional catalysis, phosphonium salt, [3+2] reaction, acylation 1. Introduction 2. Bifunctional TAPS catalysis Environmentally-friendly chemical syntheses are 2-1. Catalyst design challenges desired for creating a sustainable society. In the field of catalysis development, organocatalysts have emerged as Phosphonium salts are phosphorus(V) compounds green catalysts and great progress in their use has been widely used in organic synthesis as precursors of Wittig made over the past two decades. Most organocatalysts reagents, phase transfer catalysts, ionic liquids, and other have been designed to achieve stereocontrol, especially applications.1 Tetraarylphosphonium salts (TAPS), which enantiocontrol, in asymmetric reactions, whereas there are stereoelectronically tunable, are attractive scaffolds are relatively limited numbers of reports on catalysts for organocatalysts.2 As shown in Figure 1, it is expected that enable the control of chemoselectivity intentionally that TAPS bearing a hydroxyl group on an aromatic ring in non-asymmetric reactions. -
Novel Bifunctional Chiral Squaramide-Amine Catalysts for Highly Enantioselective Addition of Mono- and Diketones to Nitroalkenes
General Papers ARKIVOC 2011 (ix) 367-380 Novel bifunctional chiral squaramide-amine catalysts for highly enantioselective addition of mono- and diketones to nitroalkenes Ze Dong,a Xiaoqing Jin,a Pengcheng Wang,a Chang Min,a Jin Zhang,a Zhe Chen,a Hai-Bing Zhou,a,b and Chune Donga,b* aState Key Laboratory of Virology, College of Pharmacy, Wuhan University, Wuhan 430071, China bKey Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China E-mail: [email protected] DOI: http://dx.doi.org/10.3998/ark.5550190.0012.927 Abstract Novel bifunctional chiral squaramide–amine organocatalysts have been developed by rational combination of pyrrolidine and a cinchona alkaloid. The catalysts promoted the enantioselective Michael addition of both mono- and diketones to a broad range of nitroalkenes providing the corresponding products in moderate to high yields with excellent enantioselectivities and diastereoselectivities (up to 96% yield, 96% ee, 98:2 dr) under mild conditions. These results demonstrate that the assembly of two chiral privileged skeletons, pyrrolidine and cinchonine with a squaramide linker is a useful strategy to reach a wider substrate scope, high reaction efficiency and enantioselectivity. The match of the chiralities between two backbones embedded in the catalysts is also critical for improving enantioselectivity. Keywords: Chiral squaramide–amine, organocatalyst, asymmetric Michael addition, pyrrolidine, cinchonine Introduction In the past decade, the organocatalytic -
Bifunctional CYP81AA Proteins Catalyse Identical Hydroxylations but Alternative Regioselective Phenol Couplings in Plant Xanthone Biosynthesis
ARTICLE Received 27 Oct 2015 | Accepted 30 Mar 2016 | Published 5 May 2016 DOI: 10.1038/ncomms11472 OPEN Bifunctional CYP81AA proteins catalyse identical hydroxylations but alternative regioselective phenol couplings in plant xanthone biosynthesis Islam El-Awaad1,2,w, Marco Bocola3, Till Beuerle1,2, Benye Liu1,2 & Ludger Beerhues1,2 Xanthones are natural products present in plants and microorganisms. In plants, their biosynthesis starts with regioselective cyclization of 2,30,4,6-tetrahydroxybenzophenone to either 1,3,5- or 1,3,7-trihydroxyxanthones, catalysed by cytochrome P450 (CYP) enzymes. Here we isolate and express CYP81AA-coding sequences from Hypericum calycinum and H. perforatum in yeast. Microsomes catalyse two consecutive reactions, that is, 30-hydro- xylation of 2,4,6-trihydroxybenzophenone and C–O phenol coupling of the resulting 2,30, 4,6-tetrahydroxybenzophenone. Relative to the inserted 30-hydroxyl, the orthologues Hc/HpCYP81AA1 cyclize via the para position to form 1,3,7-trihydroxyxanthone, whereas the paralogue HpCYP81AA2 directs cyclization to the ortho position, yielding the isomeric 1,3,5- trihydroxyxanthone. Homology modelling and reciprocal mutagenesis reveal the impact of S375, L378 and A483 on controlling the regioselectivity of HpCYP81AA2, which is converted into HpCYP81AA1 by sextuple mutation. However, the reciprocal mutations in HpCYP81AA1 barely affect its regiospecificity. Product docking rationalizes the alternative C–O phenol coupling reactions. Our results help understand the machinery of bifunctional CYPs. 1 Institute of Pharmaceutical Biology, Technische Universita¨t Braunschweig, Mendelssohnstrae 1, Braunschweig 38106, Germany. 2 Center of Pharmaceutical Engineering (PVZ), Technische Universita¨t Braunschweig, Franz-Liszt-Strae 35A, Braunschweig 38106, Germany. 3 Institute of Biotechnology, RWTH Aachen University, Worringerweg 1, Aachen 52074, Germany.