Acid Catalysis
Mostrando 1-12 de 406 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. 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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3. 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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4. 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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5. Acid-Catalyzed Z-E Isomerization of γ-Alkylidenebutenolides: An Experimental and DFT Study
The Z-E isomerization of γ-alkylidenebutenolide analogues to natural nostoclides and other natural butenolides was investigated using 1H nuclear magnetic resonance (NMR) and high performance liquid chromatography (HPLC) data as well as density functional theory (DFT) calculations at the wB97x-D/6-31G(d,p) level, including solvent effects with the polarizabl
J. Braz. Chem. Soc.. Publicado em: 2020-01
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6. LIPASE - CATALYZED FORMATION OF PENTYL NONANOATE USING SCREENED IMMOBILIZED LIPASE FROM Rhizomucor meihei
Abstract Bio-catalysis has attracted the special attention of industrial flavour producers in the production of valuable ester compounds. In this study, the synthesis of pentyl nonanoate ester (a short chain ester with fruity aroma) was carried out with a commercial immobilized lipase from Rhizomucor meihei Lipozyme (RMIM) as biocatalyst in the esterificatio
Braz. J. Chem. Eng.. Publicado em: 09/12/2019
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7. Catalytic Transformation Conditions of Ethanol on Dealuminated BEA Zeolites
Catalysis is an important tool in obtaining a range of derivative products from renewable sources, such as ethanol. Solid-state dealumination using ammonium hexafluorosilicate on the BEA zeolite under the treatment at temperature of 190 °C, 70 mol% dealumination in the presence of humidity and washing with buffer solution at 25 °C generated larger pores. T
J. Braz. Chem. Soc.. Publicado em: 21/10/2019
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8. Estudio de las propiedades, estructurales, morfológicas y ópticas de nanopartículas de Cr2O3 sintetizadas por procesos de combustión de un solo paso y diferentes combustibles
ABSTRACT This research presents a novel one–step solution combustion synthesis to obtain nano-structured Cr2O3 from chrome nitrate solution and one fuel such as aspartic acid (Asp) or Lysine (Lys), or Autor Restrihydroxymethylaminomethane (Tris) or ethylenediaminetetraacetic acid (Edta). Once obtained, the ashes were calcined at 500°C. The powders were ch
Matéria (Rio J.). Publicado em: 16/09/2019
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9. Synthesis and Characterization of Modified Polystyrene with Oleic Acid and an Allyl Ester Derivative
Polystyrene (PS) is one of the most widely used polymers in the world, having a wide applicability. PS can be used in pure or modified forms, and the commercial materials most used for modifications are non-renewable and have high costs. For this reason, studies have been carried in order to evaluate renewable components application such as vegetable oils, f
Mat. Res.. Publicado em: 05/09/2019
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10. SYNTHESIS AND THEORETICAL STUDY OF HPW CATALYSTS SUPPORTED ON NIOBIA CALCINATED AT 500 AND 600 ºC
Keggin heteropolyacids (HPW) supported on niobia have been considered for both homogeneous and heterogeneous catalysis due to its special features, like the strong Brönsted acidity, low volatility, high activity and high selectivity for various reactions in comparison with mineral acids. Literature reports many different preparation methods for these cataly
Quím. Nova. Publicado em: 26/08/2019
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11. Protein identification from the parotoid macrogland secretion of Duttaphrynus melanostictus
ABSTRACT Background: Bufonid parotoid macrogland secretion contains several low molecular mass molecules, such as alkaloids and steroids. Nevertheless, its protein content is poorly understood. Herein, we applied a sample preparation methodology that allows the analysis of viscous matrices in order to examine its proteins. Methods: Duttaphrynus melanostic
J. Venom. Anim. Toxins incl. Trop. Dis. Publicado em: 19/08/2019
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12. COMO OBTER NANOPARTÍCULAS DE OURO USANDO SUCO DE LIMÃO?
This article refers about a green method for the preparation of gold nanoparticles using juice from four types of lemon (Tahiti, Key lime, Sicilian and Rangpur). The approach is based on a classic synthesis of nanoparticles using sodium citrate as reducing agent, since all these lemon varieties have citric acid in their compositions. Several characterization
Quím. Nova. Publicado em: 2018-05