Catalysis
Mostrando 1-12 de 1422 artigos, teses e dissertações.
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1. Extraction and Characterization of Pequi Seed Oil for Biodiesel Production: A Green Management of Waste to Biofuel Using Ethanol and Heterogeneous Catalysis
This work reports the characterization of a vegetable oil extracted from pequi seeds, an agroindustrial residue, and its biodiesel production using ethanol and heterogeneous catalysis. The pequi seeds showed 40.73 wt.% of extractive content, which represents a large amount of the biomass composition. The crude oil extracted from the pequi seeds with ethanol
Journal of the Brazilian Chemical Society. Publicado em: 2022
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2. RECENT ADVANCES IN CYANATION REACTIONS
Transformations involving structurally complex molecules, natural products and representative molecules are extremely important to obtain key reaction intermediates, in addition to accessing molecules with bioactive properties. The development of cyanation methodologies in those molecules becomes important, because nitriles are versatile and important buildi
Química Nova. Publicado em: 2022
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3. NORBORNADIENO: SÍNTESE E APLICAÇÕES
Bicyclo[2.2.1]hepta-2,5-diene or norbornadiene (NBD) is a bicyclic hydrocarbon molecule used in many fields of chemistry since its first synthesis in 1950. NBD is the precursor of Aldrin, an agrochemical that was commonly used as an insecticide until the end of the XX century. Norbornadiene is capable of interconverting into its isomer, quadricyclane (QC), b
Química Nova. Publicado em: 2022
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4. Magnetized Biochar as a Gold Nanocatalyst Support for p-Nitrophenol Reduction
The biomass use is of considerable ecological and economical interest and here, biochar, a by-product of biomass carbonization, is magnetized with Fe3O4 for its use as gold nanoparticle (NP) support towards catalysis of p-nitrophenol (4-NP) reduction. Biochar was synthesized from coffee straw biomass via pyrolysis, while magnetite functionalization was obtai
J. Braz. Chem. Soc.. Publicado em: 2021-08
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5. A Catalysis Guide Focusing on C–H Activation Processes
From the recent development of catalytically controlled C-H activation with amenable synthetic routes obviating many challenges, the demand for this strategy has raised significantly to perform complex organic transformations. The impact of the achieved results in both homogeneous and heterogeneous catalysis reflects its efficacy in modern synthetic chemistr
J. Braz. Chem. Soc.. Publicado em: 2021-05
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6. Synthetic Studies toward (−)-Cleistenolide: Highly Stereoselective Synthesis of New γ-Lactone Subunits
This study describes the stereoselective synthesis of two new γ-lactones in 6 and 3 steps and 19 and 32% yield, respectively, directed toward the total synthesis of the natural product (−)-cleistenolide. The starting material was an enantiomerically pure diacetonide diol, derived from d-mannitol with the required stereocenters for (−)-cleistenolide synt
J. Braz. Chem. Soc.. Publicado em: 2021-04
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7. IMIDAZOL E CATÁLISE: UM PAR PERFEITO
The imidazole (IMZ) ring presents several chemical properties that turns it into a versatile acid-basic/nucleophilic catalyst. The discovery of the biological properties of histidine (amino acid with IMZ ring) instigates the study of this class of compounds. It is found in nature in several enzymes such as chymotrypsin and RNAses due to these properties. Thi
Quím. Nova. Publicado em: 2021-03
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8. WILHELM OSTWALD PARA ALÉM DO ANTIATOMISMO
The Baltic German chemist Wilhelm Ostwald (1853-1932) had his scientific prestige eclipsed in the history of chemistry due to his rejection to atomic theory, which suggests the permanence of the whig interpretation on history of chemistry in the narratives about him. In this paper, we intend to present elements on Ostwald’s biography far from his role in t
Quím. Nova. Publicado em: 2021-02
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9. Theoretical Study of the Reactivity of Phenyl Radicals Toward Enol Acetates
Arylation reactions are an important class of reactions and allow the synthesis of natural and synthetic products. Despite the efficient, but high cost and toxic methodologies involving transition metals, radical arylations have gained importance after the advent of photoredox catalysis. Arylation of enol acetates is an important tool for obtaining aryl keto
J. Braz. Chem. Soc.. Publicado em: 2021-02
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10. Mitral Valve Replacement with Regent Aortic Valve in Severe Mitral Stenosis
Arylation reactions are an important class of reactions and allow the synthesis of natural and synthetic products. Despite the efficient, but high cost and toxic methodologies involving transition metals, radical arylations have gained importance after the advent of photoredox catalysis. Arylation of enol acetates is an important tool for obtaining aryl keto
Int. J. Cardiovasc. Sci.. Publicado em: 2021-02
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11. Mechanistic Investigation of DBU-Based Ionic Liquids for Aza-Michael Reaction: Mass Spectrometry and DFT Studies of Catalyst Role
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)-based ionic liquids (ILs) has exhibited a high catalytic activity in the aza-Michael reactions compared to conventional catalysts and with imidazole-based ILs. In the present work DBU-based ILs showed high catalytic potential for aza-Michael addition of aromatic amines to 2-cyclohexen-1-one under solvent-free conditio
J. Braz. Chem. Soc.. Publicado em: 2020-09
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12. Consumo de Oxigênio e Aptidão Cardiorrespiratória | Diferença entre Idade Cronológica e Biológica
Biodiesel made from oils is rich in polyunsaturated fatty acids methyl esters, and, consequently, presents high tendency to oxidize. Biodiesel made from fats, on the other hand, is mainly comprised by saturated chains. Although it is highly stable, they easily crystalize at low temperatures. Blends from both can exhibit optimized properties. In this work, ox
Arq. Bras. Cardiol.. Publicado em: 2020-09