Mechanisms Of Catalyzed Reactions
Mostrando 1-12 de 34 artigos, teses e dissertações.
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1. Theoretical Calculations on the Mechanism of Hydrogenation of Diphenylacetylene over Pdn (n = 1-4) Clusters
Diphenylacetylene (DPA) is a precursor of stilbene and benzil, and reduction of DPA or its derivatives with metallic reagents is both an old and contemporary topic of research. By means of density function theory (DFT) calculations, a detailed investigation of the mechanism of the hydrogenation of DPA over Pd clusters was carried out at the molecular level.
J. Braz. Chem. Soc.. Publicado em: 2020-10
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2. Introdução à físico-química orgânica utilizando um colorímetro artesanal - uma prática interdisciplinar
Herein, we propose an interdisciplinary experiment for undergraduate course that involves concepts of organic and physical chemistry. Firstly, we propose the synthesis of three nitrophenyl acetates, varying the substituent position. Afterwards, we describe the construction of a homemade colorimeter using inexpensive materials and LED as both emission and det
Quím. Nova. Publicado em: 2017-02
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3. Luz: um raro produto de reação
The production of visible light by chemical reactions constitutes interesting and fascinating phenomena and several reaction mechanisms are discussed to rationalize excited state formation. Most efficient chemiluminescence reactions are thought to involve one or more electron transfer steps and chemiexcitation is believed to occur by radical annihilation. A
Química Nova. Publicado em: 2011
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4. Mechanistic insights of organic reactions catalyzed by palladium : Heck, oxa-Heck and Buchwald-Hartwig coupling by ESI-MS/MS / Perspectivas mecanisticas de reações organicas catalisadas por paladio : Heck, oxa-Heck e acoplamento de Buchwald-Hartwig por ESI-MS/MS
A espectrometria de Massas por eletronspray (ESI-MS) tornou-se um método prático para o estudo de mecanismos reacionais em solução. Neste trabalho importantes reações catalisadas por paládio: reação de Heck-Mizoroki, oxa-Heck e o acoplamento de Buchwald-Hartwig foram monitoradas por ESI-MS visando interceptar espécies que comprovam as atuais propos
Publicado em: 2009
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5. Aspectos do envelhecimento cerebral e função cognitiva em modelo experimental animal e estudo de mecanismos de neurodegeneração em cultura celular
The two phenomena, biological and behavioural, approached in the present work are brain aging and spatial memory. Several studies, comparative and experimental, have shown that aged subjects present significantly impaired performances in different types of cognitive tasks. It is also known that contradictions in literature exist in relation to consequences o
Publicado em: 2007
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6. Metalloporhyrins as Biomimetical MOdels of Cytochrome P450 in the Oxidation of Pesticides / Metaloporfirinas como modelos biomiméticos do citocromo P450 na oxidação de pesticidas"
In this work we investigated the ability of metalloporphyrin model systems to mimic the action of cytochrome P450 in the oxidation of a herbicide, atrazine. To this end, we employed the second generation commercially available metalloporphyrins metal (III) 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin chloride [M(TDCPP)Cl] and metal (III) 5,10,15,20- tetr
Publicado em: 2006
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7. Preparation and characterization of mixed modified electrodes used in electrocatalytic hydrogenation of organic substrates / Preparação e caracterização de eletrodos modificados mistos e seu uso em hidrogenação eletrocatalítica de substratos orgânicos
This thesis describes the preparation of new modified electrodes (MEs) using the method of noble metal particles deposition like nickel, palladium and platinum in the surface of commum metals particles as cooper and iron. This new electrodes were denominated mixed MEs, and can show different caractheristics and present higher efficiency than others already s
Publicado em: 2006
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8. SURVEY AND SUMMARY: Recent advances in the elucidation of the mechanisms of action of ribozymes
The cleavage of RNA can be accelerated by a number of factors. These factors include an acidic group (Lewis acid) or a basic group that aids in the deprotonation of the attacking nucleophile, in effect enhancing the nucleophilicity of the nucleophile; an acidic group that can neutralize and stabilize the leaving group; and any environment that can stabi
Oxford University Press.
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9. Do cleavages of amides by serine proteases occur through a stepwise pathway involving tetrahedral intermediates?
The mechanism of the serine protease-catalyzed cleavage of amides (acylation) was examined in terms of the basicity of the functional groups participating in the catalysis. It is proposed that the reaction does not proceed through a stepwise pathway, as opposed to the cleavage of esters and anilides, which start with general base-catalyzed formation of the t
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10. Differential depolymerization mechanisms of pectate lyases secreted by Erwinia chrysanthemi EC16.
The four pectate lyases (EC 4.2.2.2) secreted by Erwinia chrysanthemi EC16 have been individually produced as recombinant enzymes in Escherichia coli. Oligogalacturonates formed from polygalacturonic acid during reactions catalyzed by each enzyme have been determined by high-performance liquid chromatography analysis. PLa catalyzes the formation of a series
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11. Convex Arrhenius plots and their interpretation
This paper draws attention to selected experiments on enzyme-catalyzed reactions that show convex Arrhenius plots, which are very rare, and points out that Tolman's interpretation of the activation energy places a fundamental model-independent constraint on any detailed explanation of these reactions. The analysis presented here shows that in such syste
The National Academy of Sciences.
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12. The deoxyxylulose phosphate pathway of isoprenoid biosynthesis: Studies on the mechanisms of the reactions catalyzed by IspG and IspH protein
Earlier in vivo studies have shown that the sequential action of the IspG and IspH proteins is essential for the reductive transformation of 2C-methyl-d-erythritol 2,4-cyclodiphosphate into dimethylallyl diphosphate and isopentenyl diphosphate via 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate. A recombinant fusion protein comprising maltose binding protein
The National Academy of Sciences.