Organic Solvent
Mostrando 1-12 de 380 artigos, teses e dissertações.
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1. Sustainable and Reusable Sulfonic Acid-Functionalized Task-Specific Ionic Liquid Catalysts for Multicomponent Reactions. A Review
Improvements in Sustainable Organic Synthesis are usually related to the investigation of less hazardous, non-corrosive and renewable materials, as well as waste prevention, energy efficiency, solvent-free reactions, and the development of efficient reusable catalysts. In this context, multicomponent reactions emerged as important strategies for the rapid an
Journal of the Brazilian Chemical Society. Publicado em: 2022
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2. Supercritical Carbon Dioxide Effect on Lipase-Catalyzed Geranyl Acetate Synthesis
This work provides a general insight on lipase-catalyzed synthesis of geranyl acetate through esterification of geraniol with acetic acid. Although this reaction is relatively well known, the replacement of organic solvents by supercritical fluids is fairly recent and the role of CO2 is still not completely understood. Therefore, reactions were performed wit
Journal of the Brazilian Chemical Society. Publicado em: 2022
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3. What is new in non-chromatographic flavonoid purification?
Flavonoids are metabolites occurring in all plant tissues and present different biological activities. They occur in a mixture of similar polarity with laborious separation and purification processes, usually furnishing low yields. Semi-preparative chromatographic methods are universally employed procedures for their isolation. This paper discusses the state
Química Nova. Publicado em: 2022
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4. Evaluation of the Structural Integrity of Layered Double Hydroxides and Mesoporous Silica During the Preparation of Heterostructures
Heterostructures constructed with mesoporous silica and layered double hydroxides are interesting for catalytic and drug delivery applications. Different arrangements between these phases are possible. In this study, we prepared heterostructures by embedding layered double hydroxides phases [M4Al2(OH)12](CO3) (M = Mg2+ or Zn2+) within the MCM41 mesoporous si
Journal of the Brazilian Chemical Society. Publicado em: 2022
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5. Novel Greener Microwave-Assisted Deprotection Methodology for the 1,3-Dioxolane Ketal of Isatin Using Calix[n]arenes
In this work, the combined use of p-sulfonic acid-calix[n]arene and microwave energy to hydrolyze the 1,3-dioxolane ketal of isatin was evaluated with excellent results. This is the first time that p-sulfonic acid-calix[n]arene has been used as the catalyst in a ketal hydrolysis reaction and the deprotection of the ketone carbonyl of isatin is reported. The
Journal of the Brazilian Chemical Society. Publicado em: 2022
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6. HPLC METHOD IMPROVEMENT FOR 4-NONYLPHENOL DETERMINATION IN ANAEROBIC REACTORS: DECREASING SOLVENT CONSUMPTION AND WASTE GENERATION
The aim of this study was to develop a chromatographic method for 4-NP determination in anaerobic batch reactors using low amount of organic solvents and also evaluate 4-NP degradation in the presence of different co-substrates. Chromatographic parameters was improved for stationary phase (C-8 column), mobile phase (acetonitrile/water solution 90:10, v:v), c
Quím. Nova. Publicado em: 2020-09
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7. A SALTING-OUT ASSISTED LIQUID-LIQUID EXTRACTION FOR THE DETERMINATION OF TEBUCONAZOLE, CARBOFURAN AND IMIDACLOPRID IN WHITE AND ROSÉ WINES
Food safety is a constant and necessary concern due to the worldwide increase of the food demand. The monitoring of quality parameters demands the development of accurate, easy and fast procedures. The aim of this work was to develop a cheap, miniaturized and trustworthy salting-out assisted liquid-liquid extraction (SALLE) procedure for the determination of
Quím. Nova. Publicado em: 20/07/2020
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8. PROCESSING OF A METAL CONCENTRATE FROM GROUND WASTE PRINTED CIRCUIT BOARDS IN ACIDIC MEDIA USING HYDROGEN PEROXIDE AS OXIDANT
The recovery of precious and base metals of a metal concentrate from ground waste printed circuit boards (PCBs) is described in detail. Samples were treated with NaOHaq. to remove the soldering mask. Experiments were performed in acidic medium (HF, H2SO4, CH3COOH or H3PO4) using H2O2 as oxidant. Base metals were leached in high yields (>99 wt.%) at ~40 ºC a
Quím. Nova. Publicado em: 20/07/2020
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9. Understanding Solvent/Bixin Interactions by Raman Spectroscopy
In this work, Raman spectroscopy and density functional theory (DFT) calculations have been used in order to understand the nature of the interaction between the carotenoid bixin and organic solvents with dielectric constant varying from ca. 2 (toluene) to ca. 47 (dimethyl sulfoxide). Raman shifts registered for the main carotenoid marker band, the C=C stret
J. Braz. Chem. Soc.. Publicado em: 2020-07
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10. Separation of gadolinium and europium from chloride media by the solvent extraction technique
Abstract Obtaining rare earth elements (REE) is a complicated task, due mainly to the difficulty of separating and purifying them. Solvent extraction is the most widely used technique for separating REE, and the most common extractants used are organophosphorus acids. The low selectivity of this technique leads to the need for a high number of extraction cel
REM, Int. Eng. J.. Publicado em: 2020-03
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11. STUDY OF PARAMETERS AFFECTING THE COALESCENCE OF DIMETHYL DISULFIDE DROPS IN A MEROX UNIT
Abstract This study focuses on the coalescence of dimethyl disulfide drops with the mother phase at a flat aqueous-organic interface between dimethyl disulfide and different sodium hydroxide solutions. Drop coalescence is an important part of the Merox process for regenerating the solvent. A digital high-frame rate camera was used for recording drops coalesc
Braz. J. Chem. Eng.. Publicado em: 13/01/2020
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12. DESENVOLVIMENTO DE METODOLOGIAS ANALÍTICAS PARA DETERMINAÇÃO DE CLORPIRIFÓS EM AMOSTRAS AQUOSAS EMPREGANDO A MICROEXTRAÇÃO LÍQUIDO-LÍQUIDO DISPERSIVA SEGUIDA POR HPLC-UV
The miniaturized extraction techniques use less aggressive methods to the environment, since they generate less waste and spend a minimum of organic solvents, besides having a good selectivity and specificity in the extractions. In this context, liquid-liquid dispersive microextraction (DLLME) has been highlighting. Thus, the present article describes an opt
Quím. Nova. Publicado em: 2020-01